-

0.16

0.76

1.62

2.61

-

-

0.03

0.27

0.87

Xaraés

-

0.08

0.71

1.00

1.86

-

-

0.01

0.15

0.80

Mean

-

0.11

0.84

1.43

2.26

-

-

0.03

0.21

0.76

LSD1

-

0.07

0.37

0.82

0.95

-

-

0.02

0.10

0.22

LS2

-

<0.001

0.005

0.127

0.068

-

-

<0.001

<0.001

0.001

1Least Significant Difference (Tukey P≤0.05).

2Level of significance.

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Brachiaria spp. evaluation in Ecuador 71

Table 5. Plant height at different ages of regrowth of 5 Brachiaria cultivars during the rainy (March‒May) and dry (September‒

November) seasons in humid tropical conditions of Ecuador.

Cultivar

Plant height (cm)

Rainy season

Dry season

Age of regrowth (weeks)

Age of regrowth (weeks)

2

4

6

8

10

2

4

6

8

10

Señal

43.1

53.5

81.8

95.4

80.2

29.6

42.5

70.4

91.3

77.5

Marandú

40.3

48.8

77.2

117.1

129.8

32.4

30.0

41.5

55.0

67.8

Mulato II

47.7

57.3

83.5

108.3

129.2

32.5

31.2

43.1

57.9

75.8

Piatá

45.8

63.8

98.8

132.1

137.1

32.0

39.2

65.7

95.4

105.5

Xaraés

54.5

71.6

91.2

126.3

137.8

32.3

48.3

71.0

91.3

103.5

Mean

46.3

59.0

86.5

115.8

122.8

31.8

38.2

58.4

78.2

86.0

LSD1

9.4

10.6

14.3

10.1

19.8

10.1

9.1

16.5

16.8

23.8

LS2

0.005

0.001

0.003

<0.001

<0.001

0.879

<0.001

<0.001

<0.001

<0.001

1Least Significant Difference (Tukey P≤0.05).

2Level of significance.

Leaf area index

the lowest SLA throughout the wet season, while Señal,

Mulato II and Marandú presented the highest values. In

During the rainy season, the leaf area index (LAI)

the dry season, cultivar differences again emerged with

followed a linear pattern for all cultivars, increasing from

Mulato II, Marandú and Señal having the greatest SLA

a mean of 0.6 at week 2 to 5.3 at week 10 (Table 6). The

and Xaraés and Piatá the lowest (P<0.01).

cultivars Mulato II and Xaraés reached the highest LAI at

week 10 of 6.6 and 5.8, respectively. Throughout the wet

Crude protein concentration

season Piatá had lower LAI than most other cultivars

(P<0.001). During the dry season, LAI followed an

Data for weeks 4, 6 and 8 on whole plant samples are

exponential pattern with the highest increase from the

presented in Table 8. Differences in crude protein

sixth week. As for the wet season, Piatá showed lower

concentration (P<0.05) between cultivars were observed

LAI than Xaraés and Mulato II by week 10 (P<0.05).

in both rainy and dry seasons, where Mulato II presented

the highest concentration at most observations. In both

Specific leaf area

seasons, mean crude protein concentration decreased as

the regrowth age increased, declining from 14.1% to 9.1%

Specific leaf area (SLA) declined in all cultivars during

in the wet season and from 12.6% to 7.6% in the dry

both rainy and dry seasons (Table 7). Piatá tended to have

season.

Table 6. Leaf area index at different ages of regrowth of 5 Brachiaria cultivars during the rainy (March‒May) and dry (September‒

November) seasons in humid tropical conditions of Ecuador.

Cultivar

Leaf area index

Rainy season

Dry season

Age of regrowth (weeks)

Age of regrowth (weeks)

2

4

6

8

10

2

4

6

8

10

Señal

0.5

2.0

3.2

3.7

5.1

0.4

0.9

1.2

2.7

4.8

Marandú

0.6

1.8

3.1

4.3

5.4

0.7

1.0

1.6

2.5

4.4

Mulato II

0.8

2.6

3.8

4.7

6.6

0.3

0.8

1.4

3.6

5.8

Piatá

0.5

1.3

2.1

3.4

3.8

0.3

0.7

1.4

2.2

3.6

Xaraés

0.7

1.9

3.5

4.9

5.8

0.3

0.9

1.6

3.6

5.9

Mean

0.6

1.9

3.1

4.2

5.3

0.4

0.9

1.4

2.9

4.9

LSD1

0.2

0.4

1.0

1.1

1.2

0.2

0.2

0.3

0.9

2.2

LS2

0.001

<0.001

0.002

0.004

<0.001

<0.001

0.045

0.016

0.001

0.03

1Least Significant Difference (Tukey P≤0.05).

2Level of significance.

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

72 J.R. Garay, S. Joaquín, P. Zárate, M.A. Ibarra, J.C. Martínez, R.P. González and E.G. Cienfuegos

Table 7. Specific leaf area at different ages of regrowth of 5 Brachiaria cultivars during the rainy (March‒May) and dry (September‒

November) seasons in humid tropical conditions of Ecuador.

Cultivar

Specific leaf area (cm2/g)

Rainy season

Dry season

Age of regrowth (weeks)

Age of regrowth (weeks)

2

4

6

8

10

2

4

6

8

10

Señal

229

246

181

190

151

248

232

173

163

164

Marandú

242

216

168

163

145

273

221

213

158

162

Mulato II

268

190

187

165

162

238

279

210

178

168

Piatá

156

129

125

124

112

221

173

148

125

112

Xaraés

207

148

134

130

132

237

213

170

142

129

Mean

221

186

159

154

140

243

224

183

153

147

LSD1

29

30

41

40

34

85

39

25

28

27

LS2

<0.001

<0.001

0.001

0.001

0.005

0.433

<0.001

<0.001

<0.001

<0.001

1Least Significant Difference (Tukey P≤0.05).

2Level of significance.

Table 8. Crude protein concentration at different ages of regrowth of 5 Brachiaria cultivars during the rainy (March‒May) and dry (September‒November) seasons in humid tropical conditions of Ecuador.

Cultivar

Crude protein concentration (%)

Rainy season

Dry season

Age of regrowth (weeks)

Age of regrowth (weeks)

4

6

8

4

6

8

Señal

13.4

11.2

9.0

11.6

7.3

6.5

Marandú

14.0

12.1

8.8

13.4

8.6

8.1

Mulato II

14.6

12.5

10.1

14.3

10.1

10.2

Piatá

13.8

10.9

8.9

12.2

8.3

6.8

Xaraés

14.6

11.1

8.6

11.6

7.4

6.5

Mean

14.1

11.6

9.1

12.6

8.3

7.6

LSD1

0.9

1.1

0.8

0.9

1.3

3.4

LS2

0.007

0.003

0.001

<0.001

<0.001

0.022

1Least Significant Difference (Tukey P≤0.05).

2Level of significance.

Discussion

The absence of cultivar differences in total DM

production during the rainy season in this study was

This plot study has provided useful information on the

similar to the findings of Rojas-Hernández et al. (2011)

potential of the Brachiaria cultivars for use in pastures of

for B. decumbens, B. brizantha cv. Libertad, B. hybrid

humid tropical Ecuador. While the grasses were planted

cv. Mulato I and cultivars of B. humidicola. Those authors

from seed, were only 12 weeks old at commencement of

also failed to demonstrate any significant differences in

observations and the study was in only a single year, the

total DM production. However, the differences we

excellent growth obtained and CP levels maintained

showed in proportions of leaf and stem in the different

indicate that these pastures can be very productive under

cultivars are important, as we showed higher production

these conditions. In fact, the DM yields obtained over

of leaves and higher CP concentration than Reyes-Purata

only 10 weeks in pastures that were only 12 weeks old at

et al. (2009). The reduction in growth in these cultivars

commencement are quite remarkable. Further studies

during the dry season was not surprising, as the major

under field conditions would clarify how well these

climatic factors that determine forage production are

preliminary findings can be extrapolated to commercial

precipitation and temperature (Gerdes et al. 2000;

situations.

Cuadrado et al. 2004). Rainfall in the rainy season and

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Brachiaria spp. evaluation in Ecuador 73

hence soil moisture was much higher than in the dry

The differences among cultivars for LAI may be

season and minimum temperatures were also lower in the

because some species such as B. decumbens are shorter

dry season. The reduction in TDM yield in the dry season

than B. brizantha, and there is a positive correlation

was somewhat lower than the 50% reduction reported by

between plant height and LAI (Guenni et al. 2005). In

Benítez et al. (2007). This marked reduction in yield

addition, LAI increases as the plant grows (Gómez-

accompanied by a drop in CP concentration indicates the

Carabalí et al. 1999), and this increase is closely related

reduced carrying capacity of these pastures during the dry

to tillering of the crop and soil cover (Rincón et al. 2007;

season.

Ramírez-García et al. 2012). Therefore, as LAI of the

The differences between cultivars in leaf DM yield we

pasture increases, the amount of light that reaches the

found in this study may be due to B. decumbens and

ground will be reduced, which can prevent or retard weed

B. brizantha having different rates of elongation in leaves

growth.

(Dias-Filho and Carvalho 2000). In this regard,

Furthermore, it has been reported that SLA in

elongation rates in leaves of 2.5 and 3.5 cm/d and leaf

Brachiaria cultivars varies according to species; Baruch

percentages in total DM of 54 and 77% in B. decumbens

and Guenni (2007) reported that at 4 weeks of age SLA in

and B. brizantha, respectively, have been reported by

B. decumbens and B. brizantha were 300 and 270 cm2/g,

Guenni et al. (2005). In addition, Hare et al. (2009)

respectively. Also, it has been reported that, as the height

reported that Xaraés and Mulato II have higher foliar

and age of the plant increase, SLA decreases (Gómez et

DM yields than other Brachiaria cultivars, especially

al. 2012), as it did in our study, because there is an

during the dry season. Similarly, Gerdes et al. (2000)

increment in the thickness of the leaves. Grasses with

reported a significant decrease in the accumulation of

greater SLA have thinner leaves and higher concen-

total DM during the period of minimum precipitation,

trations of nitrogen (Pérez et al. 2004) and higher rates of

with as much as 98% of the accumulation corresponding

photosynthesis (Reich et al. 1997), while a high SLA is

to leaf DM.

related to greater palatability and consumption by animals

The pattern of stem DM accumulation during both

(Lloyd et al. 2010; Zheng et al. 2014).

periods would have been determined by environmental

The CP values obtained in this study for Señal

conditions that affected growth of the cultivars. Stem

were higher than those reported by Alvarado et al. (1990)

production during the dry season is reduced (Cab et al.

at 6 and 9 weeks of age (9.4 and 8.8%, respectively),

2008) due to stress caused by soil moisture deficiency,

while the values obtained in Mulato II were similar to

curbing the growth of the plant and reducing stem growth

those found by Castillo et al. (2006) at 3 weeks (15%).

(Cruz et al. 2011a). Cruz et al. (2011b) reported that

The values obtained in Xaraés, Marandú and Piatá were

season has a marked effect on the relative growth of leaf

similar during the rainy season to, and higher in the dry

and stem, and differences between stem elongation rates

season than, those obtained by Pérez et al. (1999) in

of 1.2, 0.8 and 0.6 mm/stem/d in Señal, Xaraés and

B. brizantha at 6 and 9 weeks (11.9 and 8.6%,

Marandú, respectively, have been reported by Paciullo et

respectively). Water deficiency stress can have a negative

al. (2011). The marked reduction in stem growth in the

effect on Brachiaria cultivars, decreasing the con-

dry season results in increases in leaf:stem ratios in this

centration of CP. In this regard, Cuadrado et al. (2004)

season as found in this study. Leaf:stem ratios also

reported that at 24 days of regrowth CP concentration in

declined significantly as plants matured and the

the wet season was higher than in the dry season for

proportion of stem in the forage increased.

Marandú (10.5 vs. 9.3%), Señal (15.4 vs. 9.2%) and

Plant height was affected to a greater extent by

Xaraés (11.5 vs. 8.2%). Increasing age of the plant also

seasonal conditions than by cultivar. Marandú has been

decreases the concentration of CP in forage because of

shown to be quite susceptible to stress caused by soil

accumulation of dry matter (resulting in dilution of

water deficiency, presenting taller plants in the rainy

nutrients), increase in stem DM and decline in the

season (67 cm) and shorter ones in the dry season (36 cm)

proportion of leaf (Juárez-Hernández et al. 2004; Reyes-

at 35 d of regrowth (Gerdes et al. 2000). On the other

Purata et al. 2009), as shown in our study. All cultivars

hand, B. decumbens presented lower height, due to its

had CP concentrations above 7% which is considered the

decumbent growth habit, which is characteristic of this

minimum, below which intake by ruminants could be

species (Pérez et al. 1999). In this study, B. brizantha

suppressed (Lazzarini et al. 2009). The choice of cultivar

cultivars were taller than the Brachiaria hybrid and B.

to use could depend on a range of factors including DM

decumbens, which agrees with what was reported by

yield of leaf, CP concentration, rate of regrowth, response

Gómez et al. (2000).

to fertilizer etc.

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

74 J.R. Garay, S. Joaquín, P. Zárate, M.A. Ibarra, J.C. Martínez, R.P. González and E.G. Cienfuegos

Conclusions

Avellaneda C; Cabezas JF; Quintana G; Luna R; Montañez O;

Espinoza I; Zambrano S; Romero D; Vanegas J; Pinargote

While the dry season negatively affected the production

E. 2008. Comportamiento agronómico y composición

and nutritional value of forage of all grasses evaluated, the

química de tres variedades de Brachiaria en diferentes

edades de cosecha. Ciencia y Tecnología 1:87‒94.

most outstanding cultivars in terms of leaf yield, leaf area

https://goo.gl/orgr4w

index and specific leaf area were: Mulato II, Marandú and

Baruch Z; Guenni O. 2007. Irradiance and defoliation effects in

Xaraés. Xaraés certainly showed the best tolerance of dry

three species of the forage grass Brachiaria. Tropical

conditions, while performing well in terms of total DM

Grasslands 41:269‒276. https://goo.gl/ttgvtU

and leaf production in the rainy season. However, Mulato

Benítez D; Fernández JL; Ray J; Ramírez A; Torres V; Tandrón

II showed high DM yield and nutritional value over time,

I; Díaz M; Guerra J. 2007. Factores determinantes en la

which supports its further evaluation in grass production

producción de biomasa en tres especies de pastos en

systems in humid tropical conditions, especially as good

sistemas racionales de pastoreo en el Valle del Cauto, Cuba.

CP levels (11‒14%) were maintained for long periods in

Revista Cubana de Ciencia Agrícola 41:231‒235.

both rainy and dry seasons. This was a plot study and

https://goo.gl/dKPEhj

plants were only 12 weeks old when observations

Cab F; Enríquez J; Pérez J; Hernández A; Herrera J; Ortega E;

commenced, but the results do indicate that all cultivars

Quero A. 2008. Potencial productivo de tres especies de

performed well and further evaluation of the more

Brachiaria en monocultivo y asociadas con Arachis pintoi

promising cultivars under field conditions, particularly

en Isla, Veracruz. Técnica Pecuaria en México 46:317–332.

under grazing, is warranted.

Cardona C; Sotelo G; Miles JW. 2006. Resistencia en

Brachiaria a especies de salivazo: Métodos, mecanismos y

avances. Pasturas Tropicales 28(1):30‒35. https://goo.gl/

Acknowledgments

RvWXjU

Castillo MS; Vélez M; Rosas JC; Trabanino R. 2006.

We thank the Consejo Nacional de Ciencia y Tecnología

Producción y composición de los cultivares Mulato I y II de

(CONACYT) for the grant that made possible the stay of

Brachiaria híbrido inoculados con micorriza y Trichoderma

the first author in Ecuador. Our thanks to the Universidad

harzianum. Ceiba 47:25‒32. DOI: 10.5377/ceiba.v47i1-

Tecnológica Equinoccial, Campus Santo Domingo

2.444

(Ecuador) and the Facultad de Ingeniería y Ciencias of the

Cruz PI; Hernández A; Enríquez JF; Mendoza SI; Quero AR;

Universidad Autónoma de Tamaulipas (Mexico) for the

Joaquín BM. 2011a. Desempeño agronómico de genotipos

facilities provided to make this research possible.

de Brachiaria humidicola (Rendle) Schweickt en el trópico

húmedo de México. Revista Fitotecnia Mexicana 34:123‒

131. https://goo.gl/2dVuyp

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Testing functional trait-based mechanisms underpinning

(Received for publication 15 September 2016; accepted 02 May 2017; published 31 May 2017)

© 2017

Tropical Grasslands-Forrajes Tropicales is an open-access journal published by Centro Internacional de Agricultura Tropical (CIAT). This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported license. To view a copy of this license, visit

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Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Tropical Grasslands-Forrajes Tropicales (2017) Vol. 5(2):7784 77

DOI: 10.17138/TGFT(5)77-84

Research Paper

Effects of harvesting age and spacing on plant characteristics,

chemical composition and yield of desho grass ( Pennisetum

pedicellatum Trin.) in the highlands of Ethiopia

Efectos de la edad a la cosecha y del espaciamiento en las características de

planta, composición química y rendimiento del pasto desho (Pennisetum

pedicellatum Trin.) en las tierras altas de Etiopía

GENET TILAHUN1, BIMREW ASMARE2 AND YESHAMBEL MEKURIAW2

1 South Gondar Zone Agricultural Office, Debre Tabor, Ethiopia

2 Department of Animal Production and Technology, College of Agriculture and Environmental Sciences, Bahir Dar

University, Bahir Dar, Ethiopia. www.bdu.edu/caes

Abstract

The study was conducted to evaluate effects of harvesting age and plant spacing on plant characteristics, composition

and forage yield of desho grass ( Pennisetum pedicellatum Trin.). A factorial experiment with 3 harvesting ages (75, 105

and 135 days after planting) and 3 plant spacings (10 × 50, 30 × 50 and 50 × 50 cm) with 3 replications was used. The

data collected were morphological characteristics such as leaf length, plant height, number of tillers per plant and number of leaves per plant. Chemical analysis was conducted for crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL), and dry matter yield (DMY) was quantified. Results indicated

that the only morphological characteristic significantly (P<0.05) affected by plant spacing was leaf length. However,

harvesting age significantly (P<0.01) affected morphological characteristics and DMY as well as CP and NDF (P<0.05).

Dry matter yield increased dramatically as harvesting dates were delayed but plant spacing had no significant effect on

DMY. Crude protein concentration in forage declined as harvesting dates were delayed (10.9% at 75 d vs. 9.3% at 135

d). Factors such as weed control and amount of planting material required should be the criteria used by farmers to decide inter-row spacing as, within the conditions of our study, row spacing had minimal effect on yield. As only a single harvest at each age was conducted, the yields quoted in this study are not representative of the yields provided by multiple harvests at these intervals. Further studies are needed to quantify these differences.

Keywords: Biomass, harvesting day, morphological characteristics, nutritive value, plant spacing.

Resumen

En el distrito de Farta, Etiopía, se evaluaron los efectos de la edad a cosecha y la distancia de siembra de la hierba desho ( Pennisetum pedicellatum Trin.) sobre las características morfológicas de la planta, la composición química y el rendimiento de forraje. Se utilizó un experimento factorial con 3 edades a la cosecha (75, 105 y 135 días después de la

siembra), 3 espaciamientos de plantas (10 × 50, 30 × 50 y 50 × 50 cm) y 3 repeticiones. Se evaluaron las características

morfológicas: longitud de hoja, altura de planta, número de tallos por planta y número de hojas por planta; se determinaron las concentraciones de proteína cruda (PC), fibra detergente neutra (FDN), fibra detergente ácida (FDA) y

lignina detergente ácida; y se cuantificó el rendimiento de materia seca (MS). Los resultados mostraron que la longitud

de hoja fue la única característica morfológica que fue afectada (P<0.05) por el espaciamiento de siembra de las plantas, ___________

Correspondence: B. Asmare, Department of Animal Production and

Technology, College of Agriculture and Environmental Sciences,

Bahir Dar University, P.O. Box 5501, Bahir Dar, Ethiopia.

E-mail: limasm2009@gmail.com

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

78 G. Tilahun, B. Asmare and Y. Mekuriaw

mientras que la edad a la cosecha afectó tanto las características morfológicas y el rendimiento de MS (P<0.01) como la PC y la FDN (P<0.05). El rendimiento de MS aumentó marcadamente a medida que la edad a cosecha fue mayor, mientras que el espaciamiento de las plantas no tuvo un efecto significativo sobre los rendimientos obtenidos. La concentración de PC en el forraje disminuyó a medida que el intervalo de cosecha fue mayor (10.9% a 75 días vs. 9.3%

a 135 días). Los resultados de este estudio sugieren que buenas prácticas de manejo como el control de malezas

y la cantidad adecuada de material de siembra deben ser los criterios que deben utilizar los agricultores para seleccionar el espaciamiento entre hileras de siembra, ya que en las condiciones del estudio, la distancia no tuvo efecto sobre el

rendimiento. Como se realizó una sola cosecha a cada edad, los rendimientos obtenidos en este estudio no son necesariamente representativos de los rendimientos a obtenerse por múltiples cosechas en estos intervalos. Se necesitan

más estudios para cuantificar estas diferencias.

Palabras clave: Características morfológicas, día de cosecha, espaciamiento de plantas, producción de biomasa, valor nutritivo.

Introduction

Materials and Methods

Livestock production is an integral part of the subsistence

Description of the study area

crop-livestock systems in the Ethiopian highlands, as

The agronomic study was conducted in Farta district of

livestock provide draft power for land preparation and

northwestern Ethiopia located at 660 km northwest of

threshing, plus a source of cash income and assets and

Addis Ababa (11o32’‒12o03’ N, 37o31’‒38o43’ E; 2,720

nutrition for the rural communities. In addition, livestock

masl). The topography of the district is 45% gentle slopes,

are considered as a mobile bank that can be hired, shared,

29% flat land and 26% steep slopes. In terms of land use,

inherited and contracted by rural households (Amede et

an estimated 65% of the area is cultivated and planted

al. 2005). However, the contribution of this subsector to

with annual and perennial crops, while the areas under

date has been suboptimal (CSA 2015). One of the

grazing and browsing, forests and shrubs, settlements and

important constraints causing low productivity of

wastelands account for about 10, 0.6, 8 and 17%,

livestock is low quality and insufficient supply of forage

respectively. The total area of the district is estimated to

(FAO 2010). Overgrazing is common, resulting in land

be 1,118 km2. The average minimum, maximum and

degradation and low carrying capacity. As a result, the

mean temperatures are 9.3, 22.3 and 15.8 °C, respectively.

decline in desirable plant species and nutritional value of

The rainfall pattern is uni-modal (May‒September) and

the available feed resources, particularly protein, means

mean annual rainfall is 1,445 mm (FDOA 2015).

most animals are unable to obtain their maintenance

requirements from grazing (Mengistu 1987).

Treatments and experimental design

To combat this situation, the use of indigenous forage

A factorial arrangement of treatments was employed

plants as a feed source, e.g. desho grass ( Pennisetum

using a randomized complete block design with 2 factors

pedicellatum Trin.), is recommended (Leta et al. 2013;

(plant spacing and harvesting age) with 3 replications.

Asmare 2016). Desho grass is a perennial grass from

Three plant spacings within rows (10, 30 and 50 cm) were

Chencha district in southern Ethiopia (Welle et al. 2006)

compared at 3 harvesting dates (75, 105 and 135 days). In

and is currently utilized for soil conservation practices in

all treatments inter-row spacing was 50 cm. The total

the highlands of Ethiopia (Heuzé and Hassoun 2015). It is

experimental area was 10 × 19 m (190 m2) with individual

a highly popular, drought-tolerant species, and is used

plot size of 3 m2 and spacing between plots and repli-

as one of the major feeds for ruminants (Bogdan 1977;

cations of 50 and 100 cm, respectively. The land was

FAO 2010; Asmare 2016) with high production potential

prepared thoroughly by plowing at the start of the rainy

under a multi-cut harvesting regime (MRDP 1990).

season. Planting material of desho grass was collected

However, the optimum plant spacing and intervals

from a nursery site at Farta District Office of Agriculture

between harvests are not well known. The objective of

and planted on 15 July 2015. Urea fertilizer was applied

this study was to assess the effects of harvesting age and

at the rate of 100 kg/ha at planting and ammonium

plant spacing on morphological characteristics, dry matter

phosphate (DAP) was added at 25 kg/ha 21 days after

yield and nutritive value of desho grass in the highlands

establishment according to the local recommendations

of Ethiopia.

(Leta et al. 2013).

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Yield and forage quality of desho grass 79

Methods of data collection

yijk = all dependent variables (morphological data and

chemical composition) collected

Data were recorded throughout the experimental period

µ = overall mean

(June 2015‒October 2015) on leaf length (LL), plant

Hi = the effect of ith harvesting date (75, 105 and 135 days)

height (PH), leaf number per plant (LN) and number of

Sj = the effect of jth spacing between plants (10, 30 and

tillers per plant (NT). Six plants in each plot were

50 cm)

randomly selected for recording data at each harvesting

Hi*Sj = the interaction of harvesting date and spacing

date. The total herbage on each plot at the fixed dates was

eijk = random error.

harvested leaving out border rows. From each plot, an

For correlation analyses of parameters such as

area of 2.2 m2 was used to calculate dry matter (DM)

morphological characteristics, chemical composition

yield. Harvesting was done by hand using a sickle, leaving

and yield, simple bivariate Pearson correlation was

a stubble height of 10 cm, and the harvested herbage was

employed.

weighed fresh in the field using a field balance. Random

samples of fresh forage were taken and oven-dried at

Results

60 °C for 72 h to determine DM concentration, before

calculating dry matter yield (DMY). The dried desho

Morphological characteristics and dry matter yield of

grass samples were ground to pass through a 1 mm sieve

desho grass as affected by harvesting age and plant

(Wiley mill) and stored in airtight plastic bags until

spacing

required for laboratory chemical analysis. Total ash

concentration was determined according to AOAC

Overall, there were no significant interactions between

(1990). Nitrogen was determined by the Kjeldahl method

the effects of the main treatment variables (plant spacing

(AOAC 1990) and crude protein (CP) concentration was

and harvesting age) so main effects only are presented.

calculated as N% × 6.25. The neutral detergent fiber

The effects of harvesting age and plant spacing on

(NDF), acid detergent fiber (ADF) and acid detergent

morphological characteristics and dry matter yield of

lignin (ADL) concentrations were determined according

desho grass are shown in Table 1. Mean leaf length at

to Van Soest et al. (1991).

harvesting ages of 75 and 105 days was significantly

(P<0.05) greater than at 135 days (18.1, 18.8 vs. 17.4 cm,

Methods of data analysis

respectively).

Similarly, mean length of leaves was significantly

All data were analyzed using the General Linear Model

(P<0.05) greater at the narrow spacing (10 cm) than at the

(GLM) procedure of SAS (2007) for least squares

intermediate (30 cm) and wide spacings (50 cm) (19.0 vs.

analysis of variance. Mean comparisons were done using

18.2 and 17.7 cm, respectively). Harvesting age had a

Duncan’s Multiple Range Test (DMRT) for variables

significant effect on plant height (P<0.01) with height

whose

F-values

indicated

significant

difference.

increasing progressively from 46.2 cm at 75 days

Differences were considered statistically significant at

harvesting age to 69.8 cm at 105 days and 83.1 cm at 135

P<0.01 and P<0.05. The statistical model for the analysis

days (Table 1). Plant spacing had no significant (P>0.05)

of data was: Yijk = µ + Hi + Sj + Hi*Sj + eijk

effect on plant height with a mean height overall of

where:

66.4 cm.

Table 1. Morphological characteristics and dry matter yield of desho grass as affected by harvesting age and plant spacing.

Parameter

Harvesting age (days)

Plant spacing (cm)

75

105

135

Mean

10×50

30×50

50×50

Mean

Leaf length (cm)

19.0a

18.2b

17.7b

18.3

18.1a

18.8a

17.4b

18.1

Plant height (cm)

46.2c

69.8b

83.1a

63.4

67.3

66.2

65.7

66.4

Number of tillers/plant

36.4c

93.1b

106.4a

78.6

75.3b

76.7ab

83.9a

78.6

Number of leaves/plant

249c

554b

710a

508

497

498

517

504

Dry matter yield (t/ha)

7.1c

15.7b

25.5a

16.1

16.5

16.0

15.7

16.1

Mean values within rows followed by a different letter are significantly different at P<0.05.

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

80 G. Tilahun, B. Asmare and Y. Mekuriaw

Both harvesting age and plant spacing had significant

on CPY with an overall mean of 1.57 t/ha. Ash con-

effects on tiller numbers (Table 1). Mean tiller number per

centration declined significantly (P<0.01) as harvesting

plant increased from 36.4 at 75 days growth to 106.4 at

age increased with values at 75 days exceeding those at

135 days (P<0.01), while corresponding numbers for

105 and 135 days (Table 2). Progressive increases in plant

different plant spacings were 75.3 tillers/plant at 10 cm

spacing resulted in significant increases in ash

and 83.9 tillers/plant at 50 cm (P<0.05). Leaf number per

concentration (Table 2).

plant, which, in part, determines the photosynthetic

Organic matter (OM) concentration increased

capacity of the plants, was significantly (P<0.01) affected

progressively (P<0.01) as harvesting age increased and

by harvesting age, while plant spacing had no effect on

decreased progressively (P>0.05) as plant spacing

this parameter (P>0.05) (Table 1). Number of leaves per

increased (Table 2). While NDF concentration increased

plant increased from 249 leaves at 75 days to 410 leaves

significantly as harvesting age (P<0.05) and plant spacing

at 135 days.

(P<0.05) increased, ADF concentration increased

The DM yield of desho grass was significantly

significantly (P<0.01) with increase in harvesting age but

(P<0.01) affected by harvesting age but not by plant

was unaffected (P>0.05) by plant spacing (Table 2). The

spacing (P>0.05) (Table 1). Total DM harvested in-

highest ADF concentration (48.1%) was recorded in

creased progressively from 7.1 t/ha at 75 days of age to

desho grass harvested at 135 days and grown at 50 cm

25.5 t/ha at 135 days of age. Mean DM yield overall for

plant spacing.

the different plant spacings was 16.1 t/ha.

Correlation among morphological characteristics and

Chemical composition of desho grass as affected by

chemical composition of desho grass

harvesting age and plant spacing

The relationships among morphological parameters,

The chemical composition of desho grass as affected by

nutritional parameters and yield of desho grass are shown

harvesting age and plant spacing is shown in Table 2. The

in Table 3. The analysis showed that DM % and DMY

DM concentration showed minimum variation and ranged

were positively correlated (P<0.01). These parameters

from 88.2 to 89.1%. Crude protein (CP) concentration

were also positively correlated with most chemical

was significantly affected (P<0.05) by harvesting age,

parameters, e.g. CPY plus NDF, ADF, ADL and OM

declining from 10.9% at 75 days to 9.3% at 135 days.

concentrations. This indicated that, as the DM %

Crude protein yields (CPY) increased progressively and

increased, cell wall constituents also contributed to the

significantly (P<0.01) as growth period increased (0.76

increase in DMY. However, DM % and DMY were

t/ha at 75 days to 2.36 t/ha at 135 days; Table 2). By

negatively correlated (P<0.01) with CP % and total

contrast, plant spacing had no significant effect (P>0.05)

ash %.

Table 2. Chemical composition of desho grass as affected by harvesting age and plant spacing.

Parameter

Harvesting age (days)

Plant spacing (cm)

75

105

135

Mean

10×50

30×50

50×50

Mean

Dry matter (%)

88.2b

88.4b

89.0ab

88.5

89.1a

88.3b

88.2b

88.5

Ash (%)

9.16a

7.89b

7.0b

8.0

6.15c

8.15b

9.74a

8.1

Organic matter (%)

79.1c

80.6b

82.0a

80.6

83.0

80.2

78.5

80.9

Crude protein (%)

10.9a

10.2ab

9.3b

10.2

9.6

10.2

10.7

10.2

Crude protein yield (t/ha)

0.8c

1.6b

2.4a

1.57

1.5

1.6

1.6

1.6

Neutral detergent fiber (%)

45.2b

46.2b

51.7a

47.7

45.2c

47.8ab

50.1a

47.7

Acid detergent fiber (%)

33.1c

37.6b

42.6a

37.8

37.6

38.1

41.5

38.1

Acid detergent lignin (%)

17.3b

18.3b

20.7a

18.8

16.9c

18.8b

20.5a

18.7

Within parameters and treatments, means with different letters within rows are significantly different (P<0.05).

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Yield and forage quality of desho grass 81

Table 3. Correlation coefficients among morphological parameters, nutritional parameters and yields of desho grass.

DM DMY

CP

CPY

Ash

OM

NDF

ADF

ADL

LL

NT

PH

NL

DM

1

0.55** -0.43*

0.44*

-0.69** 0.81**

0.41*

-0.064

0.063

-0.02

0.31

0.44*

0.40*

DMY

1

-0.62** 0.95** -0.45*

0.50**

0.49** 0.59** 0.59** -0.42*

0.87** 0.94** 0.92**

CP

1

-0.29

0.26

-0.32

-0.26

-0.17

-0.08

0.18

-0.40*

-0.44*

-0.44*

CPY

1

-0.41*

0.44*

0.44*

0.63** 0.62** -0.43*

0.87** 0.93** 0.91**

Ash

1

-0.98** -0.41*

0.029

0.28

-0.23

-0.35

0.47*

0.44*

OM

1

0.44*

-0.40

-0.24

-0.18

0.36

0.49** 0.46*

NDF

1

0.12

-0.009

-0.27

0.03

0.47*

0.42*

ADF

1

0.6**

-0.46*

0.65** 0.58** 0.63**

ADL

1

0.62** 0.55** 0.53** 0.54**

LL

1

-0.29

-0.30

-0.30

NT

1

0.95** 0.97**

PH

1

0.97**

NL

1

Level of significance: ** = P<0.01; * = P<0.05; DM = dry matter %; DMY = dry matter yield; CP = crude protein %; CPY = crude protein yield; Ash = ash %; OM = organic matter %; NDF = neutral detergent fiber %; ADF = acid detergent fiber %; ADL = acid detergent lignin %; LL = leaf length; NT = number of tillers per plant; PH = plant height; and NL = number of leaves per plant.

Discussion

increase in tiller number, leaf formation, leaf elongation

and stem development. Similarly, Melkie (2005) reported

Plant characteristics and their relation with DM yield

that yield of Bana grass increased as harvesting stage

increased.

The absence of any significant effect of plant spacing on

The observed high number of leaves per plant at later

dry matter yield (DMY) (P>0.05) was at variance with

stages of harvesting reinforces the findings of Asmare

the findings of Melkie (2005), who demonstrated the

(2016) with the same grass species, Butt et al. (1993) and

highest DMY at narrow spacing, which he attributed to

Melkie (2005) with Bana grass and Zewdu et al. (2002)

the greater number of plants per unit area. In our study the

with Napier grass. Generally, the longer the vegetative

higher plant population at narrow plant spacing was

phase and the taller the plant, the greater the number of

counteracted to some extent by the greater number of

leaves produced (Hunter 1980), a situation reflected in our

tillers per plant produced at wider plant spacing, although

study as the number of leaves from new tillers generally

individual leaves were longer at narrow plant spacing.

increased with increase in age at harvesting. The increase

The finding that narrow plant spacing (10 and 30 cm)

in plant height with harvesting age was not unexpected.

produced longer leaves than wider spacing (50 cm)

In the same grass species, Asmare (2016) showed that

supports the results of Yasin et al. (2003), who reported

plant height increased as plant age at harvest advanced to

that narrow spacing in Napier grass increased interplant

120 days. Increments in plant height at later harvest stages

competition, causing individual plants to grow taller with

longer internodes, plus slender, thin and weak stalks

could be due to massive root development and efficient

due to poor light exposure and hence poor photosynthetic

nutrient uptake, allowing the plant to continue to increase

output. However, Melkie (2005) and Alemu et al. (2007)

in height as mentioned by Melkie (2005).

reported the opposite effect for Bana grass ( Pennisetum

The current finding that the number of tillers per plant

purpureum × Pennisetum americanum hybrid), where

increased as plant spacing increased agrees with Melkie

leaf length at relatively narrow plant spacing was shorter

(2005), who reported similar results for Bana grass. At

than at medium and wider plant spacings.

wider spacing, light can easily penetrate to the base of the

The higher dry matter yields at later stages of

plant and this may have stimulated tiller development.

harvesting were to be expected as plants were taller, had

Moreover, under wider spacing competition for nutrients

more tillers per plant and more leaves per plant. All these

is less, so individual plants can support more tillers. For

characteristics would contribute to increased photo-

Napier grass, Yasin et al. (2003) reported that, when

synthetic activity and hence higher DM production.

sufficient space is available to the individual plant, there

Ansah et al. (2010) showed that total herbage yield in

is capacity to increase the number of tillers per plant with

Napier grass increased with increase in harvesting age

the variation among the different spacings being ascribed

(60<90<120 days), which these authors attributed to the

to variable nutritional areas and access to light.

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

82 G. Tilahun, B. Asmare and Y. Mekuriaw

At narrow spacing, plants reach maturity before the

Chemical composition and its relation to yield

achievement of optimal leaf area, which is important for

estimating pasture productivity. Thus, the lower tiller

Chemical analyses of forage in this study revealed that

counts at narrow plant spacing may be due to high plant

results conformed with other studies in terms of the

competition for resources, namely light, space and

effects of age at harvest on quality parameters. As would

nutrients. The increased competition for light causes

be expected, the highest CP concentration was obtained at

reduced growth and tillering capacity. Interplant com-

the earliest stage of harvesting, with values declining as

petition in grass causes rapid and exhaustive height

harvesting was delayed. This result agrees with the

increments, so that overcrowding results in neighboring

findings of Asmare (2016) for the same species.

plants producing weak tillers (Boonman 1993). There-

Similarly, Bayble et al . (2007) and Ansah et al . (2010)

fore, the competitor plants are forced to grow upright to

reported for Napier grass a decreasing trend of CP with

dominate other tillers produced on the same plant rather

increase in harvesting age (60>90>120 days). This

than expanding laterally by bearing more tillers.

phenomenon is referred to as a growth dilution effect with

Desho grass harvested at young age in this study

increase in structural carbohydrate content of forage

had excellent nutritional value, particularly high CP

materials harvested at late maturity reducing the

concentration, a limiting nutrient in tropical forages.

percentage of protein in the forage.

Even forage cut at 135 days of age had CP concentrations

Despite the reduction in CP percentage with time,

well above 7.0%, which is the level below which

crude protein yield (CPY) increased significantly as

voluntary intake of ruminants might be depressed. All of

harvesting was delayed. Similar findings have been

the forage produced would provide sufficient energy and

reported by Asmare (2016) for the same grass species and

protein to support some level of production above a

by Melkie (2005), who recorded mean CPYs at 60, 90 and

maintenance level. However, harvesting at the early

120 days of age of 0.47, 0.91 and 0.85 t/ha, respectively,

stage resulted in low DM yields at that harvest.

in Bana grass. Obviously, decisions on the optimal time

Allowing the plants to grow until 135 days of age resulted

to harvest desho grass will depend on a compromise

in much higher yields without a great reduction in

between yield and quality of forage.

quality despite some reduction in CP concentration and

However, plant spacing had no marked effect on CPY.

increase in NDF. In any pasture situation, compromises

Since CPY is the product of total DM yield and CP

between quality and yield must be made when

concentration in the plant and there were no significant

deciding at what stage to harvest or graze a crop or

effects of plant spacing on either of these parameters,

pasture.

one would not expect to record a significant outcome.

With regard to plant spacing and forage production,

Our results are at variance with those of Melkie (2005),

both narrow and wide plant spacings have implications

who found lower CPY at a spacing of 75 × 75 cm than at

for different aspects of forage production (Rao 1986) as

100 × 50 cm.

the number of plants per unit area is the primary source of

As would be expected, neutral detergent fiber (NDF),

competition. Generally, narrow plant spacing suppresses

acid detergent fiber (ADF) and acid detergent lignin

the emergence of various weeds, but additional planting

(ADL) concentrations all increased significantly (P<0.05)

material is required. When density is maintained above

as harvesting time was delayed. Increase in plant spacing

optimum, there will be greater total demand for resources

also resulted in higher NDF and ADL levels, although

that results in stress in the plants (Trenbath 1986). Wider

ADF was unaffected. While increase in stem percentage

plant spacing requires less planting material and enables

and increased lignification with maturity would account

greater tillering capacity in forage grasses but the

for the age effects, the increases with wider plant spacing

probability of weed invasion increases and may lead to

would possibly reflect larger tiller development in the

extra cost of weeding. Again compromises must be made.

wider-spaced plants. Zewdu et al. (2002) and Bayble et al .

Individual farmers may find that the optimum plant

(2007) reported that the predominant features of

density and total population differ from those of others

increasing plant density or narrow spacing were a marked

based on the resources at their disposal. Yasin et al.

reduction in leaf:stem ratio, which in turn resulted in an

(2003) indicated that the correct use of relatively

increase in cell wall and lignin concentrations in Napier

inexpensive and simple management practices such as

grass. The increasing trend of NDF concentration with

correct plant spacing, regular weeding, appropriate

increase in harvesting age agrees with Asmare (2016) for

cutting systems and application of fertilizers can help

the same grass species, where NDF concentration

increase the level of fodder production.

increased from 72.8% at 90 days to 77.7% at 150 days of

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Yield and forage quality of desho grass 83

age. Bayble et al. (2007) recorded a similar trend when

North America 1(5):923‒929. DOI: 10.5251/abjna.2010.1.

Napier grass was harvested at 60, 90 and 120 days.

5.923.929

AOAC (Association of Analytical Chemists). 1990. Official

Conclusions

methods of analysis. 15th Edn. AOAC Inc., Arlington, VA,

USA.

Asmare B. 2016. Evaluation of the agronomic, utilization,

This study has documented the increases in yield of desho

nutritive and feeding value of desho grass ( Pennisetum

grass as days to harvest are increased and has highlighted

pedicellatum) . Ph.D. Dissertation. Jimma University,

the reduction in quality, especially reduced CP concen-

Jimma, Ethiopia. http://hdl.handle.net/10568/77741

trations and increased NDF, ADF and ADL concen-

Bayble T; Melaku S; Prasad NK. 2007. Effects of cutting dates

trations, with advancing maturity. Farmers could use this

on nutritive value of Napier ( Pennisetum purpureum) grass

information to assist in making decisions based on the

planted sole and in association with Desmodium

relative importance of forage yield and quality in their

( Desmodium intortum) or Lablab ( Lablab purpureus).

operations. While delayed harvesting results in increased

Livestock Research for Rural Development 19, article #11.

www.lrrd.org/lrrd19/1/bayb19011.htm (accessed 11 May

DMY, this is at the expense of a reduction in quality.

2016)

However, these data do not present a complete picture as

Bogdan AV. 1977. Tropical pasture and fodder plants (grasses

the pasture harvested early would regrow and the

and legumes). Longman, London, UK.

reduction in yield we observed would be much greater

Boonman JG. 1993. East Africa’s grasses and fodders: Their

than actually would occur, where repeated cuttings would

ecology and husbandry. Kluwer Academic Publishers,

be made for the earlier ages of harvest.

Dordrecht, The Netherlands.

The absence of any differences in yield with variation

Butt NM; Gary B; Donart MG; Southward RD; Noror M. 1993.

in plant spacing indicates that farmers can make their

Effect of defoliation on plant growth of Napier grass.

decisions on what spacing to use based on other factors,

Tropical Science 33:111‒120.

CSA (Central Statistics Agency). 2015. Agricultural sampling

e.g. forage quality issues, weed control etc. Our findings

survey report on livestock and livestock characteristics

suggest that plant spacing within rows can be varied quite

(private peasant holdings). Statistical Bulletin 578, Addis

markedly without any variation in forage yield and within

Ababa, Ethiopia.

the bounds of the spacings we used, farmers can choose a

Heuzé V; Hassoun P. 2015. Nigeria grass (Pennisetum

spacing to suit their conditions. An important limitation

pedicellatum). Feedipedia, a programme by INRA, CIRAD,

of this study was that the measurements of total forage

AFZ and FAO. www.feedipedia.org/node/396 (accessed 02

yield at different harvest frequencies were not carried out.

February 2015)

This information would be needed before a farmer could

FAO (Food and Agriculture Organization of the United

use these data effectively in decision making. Moreover,

Nations). 2010. Grassland Index. A searchable catalogue of

leaf:stem ratio was not measured in this study, a good

grass and forage legumes. FAO, Rome, Italy. https://goo.gl/

Qsx0gi

indicator of forage quality. Both limitations of this study

FDOA (Farta District Office of Agriculture). 2015. Annual

could be addressed in future studies.

report, Farta, Ethiopia (unpublished).

Hunter RB. 1980. Increased leaf area (source) and yield of

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Melkie B. 2005. Effect of planting patterns and harvesting days

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Ansah T; Osafo ELK; Hansen HH. 2010. Herbage yield and

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cutting, source and level of fertiliser on yield and nutritional

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quality of Napier grass ( Pennisetum purpureum (L.)

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(Received for publication 26 December 2016; accepted 26 March 2017; published 31 May 2017)

© 2017

Tropical Grasslands-Forrajes Tropicales is an open-access journal published by Centro Internacional de Agricultura Tropical (CIAT). This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported license. To view a copy of this license, visit

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Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Tropical Grasslands-Forrajes Tropicales (2017) Vol. 5(2):8593 85

DOI: 10.17138/TGFT(5)85-93

Research Paper

Weeds alter the establishment of Brachiaria brizantha cv. Marandu

Malezas afectan el establecimiento de Brachiaria brizantha cv. Marandu

SIDNEI R. DE MARCHI1, JOSÉ R. BELLÉ1, CELSO H. FOZ1, JUCILENE FERRI1 AND DAGOBERTO MARTINS2

1 Universidade Federal de Mato Grosso, Barra do Garças, MT, Brazil. www.ufmt.br

2 Universidade Estadual Paulista, Faculdade de Ciências Agrárias e Veterinárias, Jaboticabal, SP, Brazil.

www.fcav.unesp.br

Abstract

The present study evaluated the effects of different periods of coexistence among the main weeds and Marandu brachiaria

grass ( Brachiaria brizantha, now Urochloa brizantha) in newly sown pasture. The experiment was conducted in a randomized block with 4 replications, with treatments being 8 coexistence periods: 0, 15, 30, 45, 60, 75, 90 and 120 days after emergence. A phytosociological assessment of the weed community was carried out at the end of the coexistence

periods, and weeds were eliminated from the appropriate treatment using herbicide. Key morphogenic parameters of the

forages were assessed at the end of the experimental period and dry matter production was determined. Results indicated

that the presence of weeds had negative impacts on the main morphogenic components, such as plant height, number of

tillers and production of leaf and stem dry matter. The presence of weeds reduced productivity in Marandu, with 15 days

competition being sufficient to reduce forage production by approximately 50%, suggesting that weed control measures

should be adopted within 15 days following emergence of seedlings of Marandu and weeds.

Keywords: Dry matter, interference, pasture renovation, weed competition.

Resumen

En un latosol localizado en Sinop, Mato Grosso, Brasil se evaluaron los efectos de la infestación de las principales malezas de la zona ( Hyptis suaveolens, Senna obtusifolia y Sida rhombifolia), en diferentes edades después de la siembra, en la producción y algunas características morfogénicas de la gramínea forrajera Brachiaria brizantha (ahora: Urochloa brizantha) cv. Marandu. Los tratamientos fueron dispuestos en un delineamiento experimental de bloques al azar con 4

repeticiones y consistieron en los períodos de convivencia: 0, 15, 30, 45, 60, 75, 90 y 120 días después de la emergencia de la gramínea. Al finalizar cada uno de estos períodos se realizó una evaluación fitosociológica de la comunidad infestante y se eliminaron las malezas utilizando un herbicida. Al término del período experimental se evaluaron los

principales parámetros morfogénicos del pasto, así como la producción de materia seca. Los resultados mostraron un

efecto negativo de las malezas en la altura de planta y el número de rebrotes, así como en la producción de materia seca

de hojas y tallos. La presencia de las malezas redujo la producción del pasto en todos los tratamientos, variando de 50%

(competencia durante los primeros 15 días) hasta 74% (120 días). Por tanto las medidas de control de las malezas deben

ser adoptadas durante las 2 primeras semanas de convivencia con el pasto Marandu.

Palabras clave: Competencia, interferencia, materia seca, renovación de pasturas.

___________

Correspondence: S.R. de Marchi, Universidade Federal de Mato

Grosso, Av. Valdon Varjão 6390, Barra do Garças CEP 78600-000,

MT, Brazil.

Email: sidneimarchi.ufmt@gmail.com

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

86 S.R. de Marchi, J.R. Bellé, C.H. Foz, J. Ferri and D. Martins

Introduction

and can reach 20,000 kg DM/ha (Benett et al. 2008). It is

considered an excellent source of good quality feed when

Historically, the livestock production model practiced by

appropriately

fertilized

and

managed.

However,

most South American ranchers has a strong extractive

nutritional value declines rapidly following flowering

aspect with little concern for protecting and renewing the

(Valle et al. 2000).

natural resources. This absence of the use of technical

All studies we found in the literature on weed control

criteria in the utilization of natural resources results in

in pastures focused on studying the effects of herbicides

accelerated degradation of pasture areas, where

on controlling unwanted plants (Silva et al. 2005; Santos

degradation is mainly characterized by loss in the

et al. 2007; Trigueiro et al. 2007). Practically no attention

productive capacity of the forage grass due to the severe

has been given to the study of interference relations

loss of soil fertility and the increase in weed infestation

between weeds and grasses, especially with regards to

(Lima and Pozzobon 2005). Renewal of the area is the

productivity and carrying capacity of the pasture.

most rational solution when a pasture becomes degraded.

This work sought to study the effects of increasing

Renewal consists basically of destroying the old

periods of weed presence on the initial development of

vegetation, correcting soil fertility and planting the

Brachiaria brizantha cv. Marandu forage.

appropriate forage species for the local conditions,

usually an exotic (introduced) species (Macedo 2009).

Materials and Methods

The process of renovating the degraded pasture, however,

is ineffective in removing the seeds left by weeds, so weed

The experimental phase of this work was conducted in a

and pasture seeds germinate together, which initiates a

pasture renewal area in the municipality of Sinop, Mato

new degradation cycle (Martins et al. 2007).

Grosso, Brazil, (11º11’29’’ S, 55º15’13’’ W), where,

Brachiaria grass ( Brachiaria brizantha, now Urochloa

according to the Köppen (1948) classification, the climate

brizantha) is one of the most cultivated forages in the

is of type Aw. Rainfall data and average, minimum and

warm regions of South America and supports a large

maximum temperatures recorded during the experimental

portion of the cattle herd. It has high forage yield,

period are shown in Figure 1. The average annual

persistence, good capacity for regrowth and relative

temperature is 27 ºC, varying between 17 and 40 ºC.

tolerance to attacks from spittlebugs such as Deois sp. The

Average annual precipitation is 1,500 mm, varying from

average annual productivity is 4,000‒8,000 kg DM/ha

1,200 to 1,800 mm.

35

600

30

500

25

400

C)

)

o (

m

e 20

r

m(

u

t

l

300

l

a

a

r

f

e 15

n

p

ia

m

R

e

200

T 10

100

5

0

0

Oct/10

Nov/10

Dec/10

Jan/11

Feb/11

Mar/11

Rainfall

T average

T minimum

T maximum

Figure 1. Average monthly rainfall and temperature during the experimental period.

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Weeds affect establishment of Marandu 87

Representative soil samples (latosol) were collected

DeR = (De/Dt) x 100 (%), where: De is the density of each

and sent for laboratory analysis, which revealed the

weed species and Dt is the total weed density; DoR refers

following chemical characteristics: pH (H2O): 3.9; soil

to the relative dominance of each species and is estimated

organic matter: 18.45 g/dm3; P: 0.04 g/dm3 (Mehlich-1);

by the formula: DoR = (DMe/DMt) x 100 (%), where:

K+: 0.04 cmmol/dm3; Ca2+: 0.09 cmmol/dm3; Mg2+: 0.03

DMe is the dry matter of each weed species and DMt is

cmmol/dm3; Al3+: 0.3 cmmol/dm3 (KCl 1 mol/L); base

the total dry matter accumulated by the weed community;

saturation: 0.16 cmmol/dm3; and effective CEC of 21%.

and RF refers to the relative frequency of each species and

Physical analysis indicated 866 g sand/kg, 39 g silt/kg and

is estimated by the formula: RF = (FAe/FAt) x 100 (%),

91 g clay/kg, characterizing the soil as having a sandy

where: FAe is the absolute frequency of each species

texture. Based on these results, calcium lime was applied

calculated by the expression: FAe = (NAe/NAt) x 100,

in the third week of September 2010 at rates of 2,000

where: NAe indicates the number of samples for a

kg/ha, while 62.5 kg P/ha (as single superphosphate), 25

determined species; NAt is the total number of samples

kg N/ha (as urea) and 37.5 kg K/ha (as KCl) were

obtained; and FAt is the sum of the absolute frequencies

broadcast on all areas in the first week of November 2010.

of all species of the weed community (Mueller-Dombois

Existing forage was removed from the experimental

and Ellenberg 1974).

area by herbicide application (glyphosate at 2.5 L/ha)

All weeds were removed from the respective plots at

followed by mechanical tillage of soil before the study

the end of each period of coexistence by spraying with

commenced in November 2010. The area was fenced to

exclude animals for the duration of the study. Seed of cv.

herbicide, and thereafter any emerging weeds were

Marandu with 70% maximum germination was broadcast

removed by applying 1.5 L/ha of herbicide formulated

on the area at a rate of 6.0 kg/ha. Seedling emergence

with 40 g acid equivalent/L of aminopyralid and 320 g

commenced in 7 days and complete emergence occurred

acid equivalent/L of 2,4-D post-emergence.

by 10 days. The experimental area was divided into 32

The grass was evaluated only at the end of the

plots, each of 16 m2 (4.0 x 4.0 m) with the central 9.0 m2

experimental period, corresponding with 120 days after

of each plot used as the sampling area. The experimental

emergence of the seedlings, when the first grass

design was a complete randomized block, with 8

inflorescences emerged. At this time plant height, number

treatments representing different periods of coexistence

of tillers per plant and number of plants per square meter

between forage and weed species (0, 15, 30, 45, 60, 75,

were measured. Forage samples were collected by cutting

90 and 120 days after emergence) and 4 replications.

the plants to 10 cm from the ground within the area

Assessments of the pasture communities for each

enclosed by the 1.0 m2 metal square, cast randomly in the

treatment were performed at the end of the coexistence

sampling area of the experimental unit.

period for that treatment with the aid of a 1.0 m2 metal

The samples were sent to the laboratory and sorted into

square randomly cast within the sampling area of each

green leaves, green stems and dead matter. The green

plot. All weed species within the metal square were

inflorescences present were considered as part of the

separately identified, counted, cut at stem base and taken

stem. The various fractions were duly packed in properly

to the laboratory, where they were placed in properly

labeled and perforated paper bags and dried in a forced-

labeled and perforated paper bags to be dried in a forced-

air circulation oven at 60‒63 ºC for 72 hours. Dry matter

air oven at 60‒63 ºC for 72 hours. After this procedure,

(DM) yields for the different fractions [green leaf dry

the dry weight of the stems and leaves of each collected

matter (GLDM), green stem dry matter (GSDM), dead

species was determined by using a 0.01 g precision

material dry matter (DMDM) and total dry matter (TDM)]

balance.

were calculated. Dry matter yields for the different

The relative importance (RI) of the weeds was

treatments were compared with those for the 0 days

calculated by the formula:

treatment (control, = weed-free throughout) to determine

RI = (IVIe/IVIt) x 100 (%), where: IVIe refers to the

the suppression in yield by exposure to weeds for the

importance index of a determined species; and IVIt

various times according to the formula:

signifies the sum of the importance indices of all

ROF = [(MST – MSPC)/MST] x 100, where: ROF is

components of the community. The importance index of

the reduction in forage offering in percent; MST is the

each species is estimated by the formula:

total DM produced by the forage species that remained

IVI = DeR + DoR + RF, where: DeR refers to the rela-

weed-free for 120 days; and MSPC is the DM produced

tive density of each species, estimated by the formula:

by treatments with differing periods of weed infestation.

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

88 S.R. de Marchi, J.R. Bellé, C.H. Foz, J. Ferri and D. Martins

The values obtained were submitted to analysis of

Results

variance by the F-test and the effects of the treatments

were compared by the Scott-Knott test at 5% probability.

Only 3 weed species emerged during the experimental

The average values of total DM produced by Marandu and

period: Hyptis suaveolens (L.) Poit. (Lamiaceae) (local

observed at 120 days were also adjusted according to the

name: cheirosa), Senna obtusifolia (L.) H.S. Irwin &

Barneby (Leguminosae – Caesalpinioideae) (local name:

Boltzmann model for better understanding of the effects

fedegoso) and Sida rhombifolia L. (Malvaceae) (local

of coexistence, as used by Kuva et al. (2001). This model

name: guanxuma). Senna obtusifolia accumulated the

conforms to the following equation:

greatest amount of DM up to 45 days after emergence

(DAE), but was the only species that showed a reduction

(A

Y =

1 − A2)

+ A

in DM accumulation at 120 DAE (Figure 2). Over the full

1 + e(x− x

2

0)/dx

120 days, H. suaveolens showed the highest DM accu-

mulation with rapid growth from 45 to 120 DAE; DM

where: Y is the estimated DM yield of the forage in g/m2;

accumulation was almost 2.5 times that of S. obtusifolia

x is the upper limit of the coexistence period or control

(Figure 2).

considered; A1 is the estimated yield obtained in the

Sida rhombifolia produced little growth up to 90 DAE,

plots maintained clean throughout the cycle; A2 is the

when compared with the other 2 species, but

minimum estimated production obtained in the units

accumulation of DM increased considerably from 90

maintained with weeds throughout the cycle; xo is the

DAE. At 120 DAE total DM produced by the weeds was

upper limit of the control or coexistence period

288 g/m2 (Figure 2).

corresponding to the intermediate value between

The relative importance, obtained from density,

maximum and minimum production; and dx is the

dominance and frequency of each of the 3 species, was

parameter that indicates the velocity loss or production

relatively equal throughout the experimental period

gain (tg α at point xo).

(Figure 3).

180

150

²)

Senna obtusifolia

Hyptis suaveolens

Sida rhombifolia

120

(g/m

re

90

attm

y

60

Dr

30

0

15

30

45

60

75

90

120

Coexistence period (days)

Figure 2. Dry matter accumulated by the weeds in their coexistence periods.

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Weeds affect establishment of Marandu 89

100

)

% 80

RI (

Senna obtusifolia

Hyptis suaveolens

Sida rhombifolia

-

60

tance

or

p 40

im

20

lative

Re

0

15

30

45

60

75

90

120

Coexistence period (days)

Figure 3. Relative importance (%) of the weed species in their respective coexistence periods.

The height of Marandu was significantly altered by

of Marandu plants did not differ between treatments

coexistence with the weeds; height of the control forage

(P>0.05) with a mean of 37.3 plants/m2 at 120 days post

at 120 days was 62 cm compared with a mean of 38 cm

emergence (Table 1). The production of green leaf, stem

for the remaining treatments (Table 1).

and total forage dry matter was significantly reduced by

Similarly, exposure to weeds for periods of >15 days

the presence of weeds in the sward, even for as little as 15

significantly reduced the number of tillers per plant (4.2

days (P<0.05; Table 2). After 120 days of growth,

and 3.8 for 0 and 15 days, respectively, vs. a mean of 2.7

total DM production was suppressed by 50%, when

for the remaining treatments; P<0.05) (Table 1). Density

weeds remained in the pasture for as little as 15 days

Table 1. Effects of duration of weed competition in a Marandu pasture on height, number of tillers per plant and density of Marandu plants at 120 days after emergence.

Days of coexistence

Height

Number of tillers

Density

(cm)

(No./plant)

(No. of plants/m2)

0

61.7a1

4.2a

40.4

15

42.7b

3.8a

30.3

30

40.5b

3.0b

42.8

45

32.5b

3.0b

32.5

60

30.2b

2.7b

40.5

75

49.0b

2.5b

32.5

90

38.0b

2.3b

38.0

120

32.5b

3.0b

41.5

F Days

3.84*

4.80*

0.86NS

F Block

0.19NS

4.08*

0.14NS

C.V. (%)

26.11

19.23

27.97

1Means followed by the same letter within columns do not differ by the Scott-Knott test at 5% probability.

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

90 S.R. de Marchi, J.R. Bellé, C.H. Foz, J. Ferri and D. Martins

Table 2. Effects of duration of weed competition on the production (kg/ha) of green leaf dry matter (GLDM), green stem dry matter (GSDM), dead material dry matter (DMDM) and total dry matter (TDM) of Marandu and reduction in forage offering (ROF) at 120

days after emergence.

Days of

GLDM

GSDM

DMDM

TDM

ROF1 (%)

coexistence

0

1,543a2

1,632a

256

3,431a

-

15

790b

710b

210

1,710b

50.2

30

610b

790b

165

1,565b

54.4

45

470b

480b

136

1,086b

68.3

60

460b

410b

193

1,063b

69.0

75

420b

490b

100

1,010b

70.6

90

530b

340b

111

981b

71.4

120

430b

350b

110

890b

74.1

F Days

5.35*

5.96*

1.41NS

6.01*

-

F Block

0.32NS

0.83NS

0.84NS

0.31*

-

C.V. (%)

49.82

54.02

58.68

47.06

-

1Reduction in forage offering relative to the control (0 days).

2Means followed by the same letter within columns do not statistically differ by the Scott-Knott test at 5% probability.

after emergence. This reduction in yield had increased to

The relationship between total DM yield and number

74% when weeds remained in the pasture for the full 120

of days that weeds remained in the pasture is presented in

days (Table 2), but there were no significant differences

Figure 4. Accordingly the suppressant effects of weeds on

between yields for the differing times that weeds

pasture growth had been expressed by 45 days after

remained in the pasture.

emergence.

3000

3,000

Y = [2,942.3/(1 + e(x-11.0738)/6))] + 890.0

)

Y = ((2942,3) / (1 + e(x-11,0738) / 6)) + 890,0*

-1

R2 = 0.8129

a) ha

R2 = 0,8129

h g (k

2000

2,000

(kg/ ld

r ie

te yats

m s

a

y m

1000

1,000

Dr ry

D

0

0

15

30

45

60

75

90

105

120

Coexi

Coe sten

xistence

ce p

per

e i

r od

iod (d

ay)

(days)

Figure 4. Relationship between forage DM yield of Marandu and duration of weed growth in the pasture.

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Weeds affect establishment of Marandu 91

Discussion

results with most rapid growth of this species between 75

and 120 DAE. It is significant that DM yields of this

This study has shown that weeds can provide severe

species at 120 days were equal to those of Marandu in the

competition for freshly sown stands of Marandu, which

unweeded plots. Sida rhombifolia, despite the low DM

reduces DM production of the grass, even if weeds are

accumulation during virtually the entire period, began

present only for a short period initially, e.g. as little as 15

to show greater vegetative growth only after 90 DAE,

days. It could be concluded that this is due to competition

which is in agreement with findings of Bianco et al.

for available resources, especially nutrients, sunlight and

(2014). When analyzing growth and mineral nutrition of

moisture.

S. rhombifolia, these authors found that the species

Interference of the weeds was most evident on the

actually has slow vegetative growth up to 80 DAE, with

height and number of tillers generated by Marandu plants.

peak DM accumulation occurring after 140 DAE.

Nepomuceno et al. (2007) reported that plant height is not

However, the authors also found that, although initial

an adequate characteristic to evaluate the competition

growth is slow, this species has a high capacity for

between species, since plants subjected to competition

absorbing nutrients from about 35 DAE and has a

prioritize height growth in search of light rather than the

comparatively higher capacity to absorb nutrients than

accumulation of total DM. Vilela (2011) commented that

other weeds. It is important to note that S. obtusifolia and

tillering is a predominant feature in most grasses, and in

H. suaveolens are annuals and S. rhombifolia is a

the case of a pasture, the success of its production is

perennial species. Annual species grow more quickly than

related to good tillering and the consequent occupation of

perennials and this was probably the main factor

spaces between plants, thereby complicating the

suppressing growth of Marandu.

establishment of weed species. In this study the opposite

The different patterns of DM accumulation of the 3

was observed, i.e. the weeds dominated the spaces and

weed species help to explain the similarity of the relative

adversely affected the emergence of tillers in the forage,

importance obtained for the various coexistence periods

even when present for only 15 days. In addition grass

used in this study. This behavior may be correlated with

plants subjected to competition from weed plants for only

competitiveness and the consequent coexistence of the 3

15 days showed lower vertical growth than those free of

weed species in the area. In other words, the weed species

weed competition and failed to compensate when weeds

complement one another, with S. obtusifolia having

were removed.

greater competitive ability in the early growth stages,

Both S. obtusifolia and H. suaveolens are annual

while H. suaveolens and S. rhombifolia are able to grow

weeds and grow rapidly early in life, growing much more

slowly during this period, being more prominent as Senna

rapidly than Marandu and the perennial S. rhombifolia.

matures (Gravena et al. 2002).

This may explain why the main suppressant effect of

With this complementary growth, there was always at

weeds on Marandu growth happened in the first 15 days

least one weed species exerting competitive pressure on

following emergence. These weeds are native to the

Marandu, resulting in similar suppression of grass growth

American continent with wide distribution in South

regardless of when weeds were removed. It must be

America, especially in Brazil, and often infest areas of

remembered that the annual weeds are more adapted to

annual crops, perennials and pastures (Fleck et al. 2003;

the environmental conditions, have characteristics that

Souza et al. 2011). Besides the competition for

make better use of the light, and are more efficient in the

environmental resources such as water, light and

use of nutrients, since they are native in the region, while

nutrients, they can also be toxic to animals if ingested

the majority of forage grasses are exotic in South America

during grazing (Pellegrini et al. 2007; Braga et al. 2012).

(Peron and Evangelista 2004; Benett et al. 2008). Most of

We found that S. obtusifolia grew most rapidly

them are also perennials with slow growth initially.

between 21 and 91 DAE, in agreement with the findings

It is noteworthy that the main broadleaf weed control

of Erasmo et al. (1997), after which growth rate decreased

method in grazing areas is the application of specific

significantly. Those authors suggested that the reduction

selective herbicides. This represents a significant

in growth was due to the natural senescence process of the

operating expense. Our study provides an indication of

species, with resources at that time being directed to

the possible reduction in pasture growth as a result of

reproduction. Studies performed by Gravena et al. (2002)

weed infestation, which may aid a farmer in making a

demonstrated that H. suaveolens accumulated only 31%

decision to spray weeds or to let them grow. It seems that,

of total DM up to 45 DAE, with most rapid growth

if the weeds are not treated early after emergence, it is not

between 60 and 140 DAE. Our findings support these

worth treating them in terms of the effects on pasture

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

92 S.R. de Marchi, J.R. Bellé, C.H. Foz, J. Ferri and D. Martins

growth in that season, as they will still have a depressant

Planta Daninha 20:189‒196. DOI: 10.1590/S0100-

effect on pasture growth, even if removed. There is a

83582002000200004

small window of opportunity to take action. The decision

Köppen W. 1948. Climatología. Gráfica Panamericana, Buenos

then becomes one of preventing seed set to reduce the soil

Aires, Argentina. https://goo.gl/vqr3vV

seed bank of the weeds for subsequent seasons. Our

Kuva MA; Gravena R; Pitelli RA; Christoffoleti PJ; Alves

PLCA. 2001. Períodos de interferência das plantas daninhas

results show that the reduced growth of Marandu from

na cultura da cana-de-açúcar. II – Capim-braquiária

weed competition was a function not of fewer grass plants

( Brachiaria decumbens). Planta Daninha 19:323‒330. DOI:

but reduced growth of the same number of plants, through

10.1590/S0100-83582001000300003

reduced numbers of tillers and reduced vertical growth.

Lima D; Pozzobon J. 2005. Amazônia socioambiental.

We are not aware of similar findings being reported in the

Sustentabilidade ecológica e diversidade social. Estudos

scientific literature.

Avançados 19:45‒76. DOI: 10.1590/S0103-40142005000

We consider that the regression equation obtained in

200004

this study should be of assistance to all professionals

Macedo MCM. 2009. Integração lavoura e pecuária: O estado

involved in the livestock production chain, especially the

da arte e inovações tecnológicas. Revista Brasileira de

meat production chain, in which the productivity of a

Zootecnia 38:133‒146. DOI: 10.1590/S1516-3598200900

forage area is heavily dependent on the presence or

1300015

absence of weeds. It should be used as a component when

Martins D; Triguero LRC; Domingos VD; Martins CC; Marchi

making decisions about weed control measures to ensure

SR; Costa NV. 2007. Seletividade de herbicidas aplicados

that the decision is soundly based economically.

em pós-emergência sobre capim-braquiária. Revista

Brasileira de Zootecnia 36:1969‒1974. DOI:

However, delaying a decision to treat weeds could have

10.1590/

S1516-35982007000900004

long-term consequences, especially in terms of additional

Mueller-Dombois D; Ellenberg H. 1974. Aims and methods of

seed added to the soil seed bank. As this study lasted for

vegetation ecology. Willey & Sons Inc., New York, USA.

only 120 days, it is difficult to forecast the productivity of

Nepomuceno M; Alves PLCA; Dias TCS; Pavani MCMD.

the pasture over subsequent years. Longer-term studies

2007. Períodos de interferência das plantas daninhas na

are needed to determine how the suppression of growth of

cultura da soja nos sistemas de semeadura direta e

the grass observed here is reflected over the complete life

convencional. Planta Daninha 25:43‒50. DOI: 10.1590/

of the pasture.

S0100-83582007000100005

Pellegrini LG; Nabinger C; Carvalho PCF; Neumann M. 2007.

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JA. 2008. Produtividade e composição bromatológica do

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capim-marandu a fontes e doses de nitrogênio. Ciência e

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JMV; Rocha DCC; Fialho CMT. 2007. Controle de

32:311‒317. DOI: 10.1590/S0100-83582014000200008

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Carvalho FP; Ribeiro KG. 2012. Ocorrência de plantas

25:149‒155. DOI: 10.1590/S0100-83582007000100016

daninhas no sistema lavoura-pecuária em função de

Silva AC; Freitas RS; Ferreira LR; Silva AA; Belo AF.

sistemas de cultivo e corretivo de acidez. Revista Ceres

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B. plantaginea sob doses reduzidas de fluazifop-p-butil,

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Fleck NG; Rizzardi MA; Agostinetto D; Vidal RA. 2003.

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Produção de sementes por picão-preto e guanxuma em

Solanum viarum em diferentes profundidades de semea-

função de densidades das plantas daninhas e da época de

dura. Revista Ceres 58:749‒754. DOI: 10.1590/S0034-

semeadura da soja. Planta Daninha 21:191‒202. DOI:

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Gravena R; Pedrinho Jr AFF; Barbosa Jr AF; Bianco S; Pitelli

MA; Cardoso LA. 2007. Seletividade de herbicidas

RA. 2002. Análise do crescimento de Hyptis suaveolens.

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na qualidade das sementes. Planta Daninha 25:341‒349.

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Vilela H. 2011. Pastagem – Seleção de plantas forrageiras,

das plantas forrageiras do gênero Brachiaria. In: Peixoto

implantação e adubação. 2nd Edn. Aprenda Fácil Editora,

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(Received for publication 12 May 2016; accepted 19 September 2016; published 31 May 2017)

© 2017

Tropical Grasslands-Forrajes Tropicales is an open-access journal published by Centro Internacional de Agricultura Tropical (CIAT). This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported license. To view a copy of this license, visit

http://creativecommons.org/licenses/by-nc-sa/3.0/

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Tropical Grasslands-Forrajes Tropicales (2017) Vol. 5(2):9499 94

DOI: 10.17138/TGFT(5)94-99

Short Communication

A simple method for determining maize silage density on farms

Un método sencillo para determinar la densidad en ensilaje de maíz a nivel

de finca

ANA MARIA KRÜGER, CLÓVES C. JOBIM, IGOR Q. DE CARVALHO AND JULIENNE G. MORO

Departamento de Zootecnia, Universidade Estadual de Maringá, Maringá, PR, Brazil. www.dzo.uem.br

Abstract

Several methodologies have been tested to evaluate silage density, with direct methods most popular, whereas indirect

methods that can be used under field conditions are still in development and improvement stages. This study aimed to

establish relationships between estimates of maize silage density determined using a direct and an indirect method, in an endeavor to provide an alternative to direct measurement for use in the field. Measurements were performed on maize

silage in 14 silos. The direct method involved the use of a metal cylinder with a saw-tooth cutting edge attached to a

chainsaw to extract a core of silage. Density of the silage was determined taking into consideration the cylinder volume

and dry matter weight of silage removed at 5 points on the silage face. With the indirect method, a digital penetrometer

was used to estimate silage density by measuring the penetration resistance at 2 points adjacent to the spots where the

silage cores were taken, i.e. 10 readings per silo. Values of penetration resistance (measured in MPa) were correlated

with the values of silage mass (kg/m3) obtained by direct measurement through polynomial regression analysis. A positive quadratic relationship was observed between penetration resistance and silage density for both natural matter

and dry matter (R² = 0.57 and R² = 0.80, respectively), showing that the penetrometer was a reasonably reliable and

simple indirect method to determine the density of dry matter in maize silage. Further testing of the machine on other

silos is needed to verify these results.

Keywords: Ensiled matter, penetrometer, resistance, silos evaluation.

Resumen

Para determinar la densidad de ensilado, los métodos más usados son los directos mientras métodos indirectos, que se

puedan usar a nivel de finca, están aún siendo desarrollados y mejorados. El objetivo de este estudio fue determinar la

correlación entre las densidades de ensilado de maíz determinadas con un método directo, y las determinadas con un

método indirecto. Las mediciones se hicieron en 14 silos de maíz de fincas lecheras en 5 municipios del estado de Paraná, Brasil. El método directo consistió en el uso de un cilindro metálico con un filo cortante de dientes serrados unido a una motosierra para extraer una muestra del ensilado; la densidad se determinó con base en el volumen del cilindro y el

promedio del peso de las muestras extraídas en 5 puntos. El método indirecto consistió en el uso de un penetrómetro

digital para medir la resistencia a la penetración en 2 puntos adyacentes a los sitios donde se tomaron las muestras del

método directo (10 lecturas por silo). Los datos se sometieron a un análisis de regresión polinomial que mostró una relación cuadrática positiva entre la resistencia a la penetración (medida en MPa) y la densidad del ensilaje con base en los valores de la masa del ensilado (kg/m3) tanto para la materia natural como la materia seca (R² = 0.57 y R² = 0.80,

respectivamente). Se concluye que el penetrómetro fue un método indirecto razonablemente confiable y sencillo para

determinar la densidad de la materia seca en ensilado de maíz. Para verificar estos resultados se requieren pruebas adicionales con este equipo en otros silos.

.

Palabras clave: Evaluación de silos, materia ensilada, penetrómetro, resistencia.

___________

Correspondence: A.M. Krüger, Departamento de Zootecnia, Univer-

sidade Estadual de Maringá, Maringá CEP 87020-900, PR, Brazil.

E-mail: anamkruger@yahoo.com.br

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Determining silage density on farms 95

Introduction

Materials and Methods

Greater compaction of ensiled material provides greater

Specific mass measurements were made by a direct

specific mass (SM) by expelling air and providing

method in 14 bunker silos (treatments), employing

anaerobic conditions for fermentation. This allows better

methodologies described by Holmes and Muck (1999)

conservation of soluble sugars, minor alteration of

and D’amours and Savoie (2005), in maize silages on

structural carbohydrates and reduced proteolysis in the

dairy farms in Paraná State, Brazil, specifically in the

resulting silage, aspects which increase acceptability and

Castro, Carambeí, Arapoti, Piraí do Sul and Ponta Grossa

consumption by livestock (Velho et al. 2007).

municipalities.

Direct methods are used to evaluate SM of silages,

A metal cylinder, 20 cm length and 10 cm diameter,

with a serrated cutting edge and attached to a chainsaw,

mostly the determination of herbage mass for a known

was used, as described by Craig and Roth (2005) (Figure

volume of silage, with values being expressed in kg of

1). The cylinder was screwed into the silage panel

natural or dry matter per cubic meter. However, these

mechanically through the rotation exerted by the

methods involve measuring the volume of the sample,

chainsaw. When the sample was withdrawn from the

taking it to a suitable facility and drying it for at least 24

storage panel of the silo, the depth was measured with a

hours in an oven. More rapid, indirect methods, which

rule to calculate the volume of the withdrawn sample.

however require sophisticated equipment, aim to facilitate

From the cylinder volume and the mass [both natural

the collection of such data under field conditions, such as:

matter (NM) and dry matter (DM)] of the withdrawn

radiometric sensors that present a source and a receptor

sample, the SM of the silage in the silo was calculated.

for gamma waves, a method based on microwave

Whereas NM was the mass of the fresh silage, DM was

resonance; and the georadar system, also used to estimate

determined conventionally (weighing after drying NM at

SM of soils (Jobim et al. 2007).

105 °C for 8 h in a forced-air oven).

However, these indirect methods are still in

Silage samples were withdrawn at 5 points (taken as

development and improvement stages and rely on strict

replications) in the silo panel, 3 locations at the top and 2

calibration to produce reliable data. Among the various

at the bottom, forming a ‘W’ like figure. Before the

invasive tools to determine SM of silages, the

sampling procedure commenced, a slice of silage had

penetrometer has specific advantages over other

been removed manually from each silo panel in order to

techniques because it requires a simple calibration

remove any loose silage from the silage ‘face’, so that the

procedure and can provide reliable data. Sun et al. (2010)

samples were collected from ‘intact’ (undisturbed) silage.

suggested that this technique, when properly applied, has

To estimate SM through the indirect method, a digital

the potential to provide good information about silage

penetrometer (DLG, model PNT-2000-M), which follows

storage conditions. In an on-station study under controlled

the ASAE S313.3 rule that defines penetration resistance

conditions, Silva et al. (2011) correlated resistance values

as the pressure over the area of a cone with a solid angle

provided by maize silage to penetration by a penetrometer

of 30°, was used. This equipment is used to determine the

penetration resistance in soil compaction studies

with SM values obtained by sampling with the use of a

(Figueiredo et al. 2011; Storck et al. 2016). Penetration

metal cylinder of known volume. Estimates of SM they

resistance was measured at the same time and using the

obtained with this indirect method compared favorably

same orientation as in the direct determination with the

with values obtained with direct measurement, causing

metal cylinder, with 2 measurements of resistance at each

them to conclude that the penetrometer could provide

silo panel point, thus giving 10 measurements in each silo.

reliable estimates under field conditions both quickly and

Penetration resistance was measured at points adjacent to

at low cost.

the spots where silage samples were taken for the direct

The objective of our study was to measure the SM of

measurements, at a distance of approximately 35 cm from

maize silage on farms by a direct method (core sampling

those.

in the silo panel) and an indirect measurement method

For resistance measurements, the penetrometer metal

(using a penetrometer), and to establish correlations

cone was manually pushed into the silage panel

between the estimates obtained, with the aim of

horizontally at a constant speed of approximately 2 cm/s

establishing the penetrometer as a reliable tool for

up to the end of the cone length, a mandatory procedure

estimating the degree of compaction of stored forage in

according to the instruction manual for the device (Figure

the field.

2). Penetration depth into the silo panel was 0.9 m.

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

96 A.M. Krüger, C.C. Jobim, I.Q. de Carvalho and J.G. Moro

direct method (in Table 1: observed SMNM and observed

SMDM). Data were not statistically analyzed, considering

that there was no replication (silo), since the silos were

evaluated on different farms and factors other than the

type of assessed silo and silage (maize) may present

different characteristics. Therefore, the values obtained

for the SMNM and SMDM were descriptively analyzed.

Figure 1. Cylinder and chainsaw in use. Source: Personal file.

Penetrometer resistance values (in megapascal, MPa)

were correlated with the SM values (kg/m³) obtained with

use of the cylinder coupled to the chainsaw by a

polynomial regression study. The regression equations

obtained were used to calculate the values of SM for

natural matter (SMNM) and dry matter (SMDM) in each

silo (in Table 1: estimated SMNM and estimated SMDM)

and these were compared with the values obtained by the

Figure 2. Penetrometer in use. Source: Personal file.

Table 1. Dry matter concentration, resistance by ensiled mass to penetration of the metal cone (± SD), observed and estimated specific mass (natural matter and dry matter basis) (± SD) in 14 farm silos.

Silo

DM1

Resistance

SMNM (kg NM/m3)

SMDM (kg DM/m3)

(g/kg)

(MPa)

Observed

Estimated

Observed

Estimated

1

327

2.20 + 0.50

839 + 80.5

767 + 45.3

274 + 26.3

260 + 11.6

2

350

1.92 + 0.35

748 + 48.8

837 + 14.9

262 + 17.1

282 + 4.8

3

292

0.24 + 0.05

469 + 90.8

571 + 17.2

137 + 26.5

146 + 7.5

4

277

0.54 + 0.10

751 + 108.7

704 + 25.7

208 + 30.1

204 + 11.6

5

294

1.07 + 0.40

876 + 49.5

850 + 47.9

258 + 14.6

271 + 24.3

6

274

1.00 + 0.14

904 + 73.0

837 + 22.1

247 + 20.0

265 + 10.7

7

336

0.99 + 0.35

787 + 62.7

836 + 49.1

265 + 21.1

264 + 24.0

8

287

0.68 + 0.22

787 + 87.4

755 + 48.4

226 + 25.1

227 + 22.1

9

279

0.74 + 0.25

801 + 22.9

773 + 50.8

223 + 6.4

235 + 23.5

10

325

1.15 + 0.29

854 + 126.2

861 + 39.2

277 + 41.0

277 + 19.3

11

391

1.06 + 0.14

710 + 103.2

847 + 23.1

277 + 40.3

270 + 11.1

12

345

0.85 + 0.37

867 + 67.4

803 + 73.7

299 + 23.2

248 + 34.1

13

278

0.48 + 0.24

776 + 59.8

684 + 62.6

216 + 16.6

195 + 28.0

14

270

0.53 + 0.18

660 + 50.6

702 + 47.2

178 + 13.6

203 + 21.2

Mean

309

0.96 + 0.58

773 + 128.5

773 + 71.0

239 + 48.4

239 + 34.3

1DM – dry matter; NM ‒natural matter; Resistance – resistance to penetration of the metal cone; SMNM – specific mass of natural matter; SMDM – specific mass of dry matter.

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Determining silage density on farms 97

Results

Discussion

The average DM concentration found in the silages

The values observed for DM concentration of the silages

evaluated was 309 g DM/kg, ranging from 270 to 391 g

evaluated are consistent with the recommendation of

DM/kg (Table 1). Density of silage as determined by the

Nussio et al. (2001) that the optimal DM concentration of

direct method (‘observed’) ranged from 469 to 904 kg/m3

maize plants at ensiling should be 300‒350 g DM/kg.

(mean 773 ± 129 kg/m3) for NM and from 137 to 299

According to these authors, DM concentrations below

kg/m3 (mean 239 ± 48.4 kg/m3) for DM. The density

300 g DM/kg are associated with lower DM yield, losses

measurements were compared with the range in

by leaching and low silage quality, factors that may lead

penetration resistance in the silos, which varied from 0.24

to reduced intake by animals. The quality of silages was

to 2.20 MPa (mean 0.96 ± 0.58 MPa). The results for this

evidenced by parameters such as neutral detergent fiber,

comparison are shown in Figures 3 and 4.

starch content and pH, which presented mean values of

46.35 ± 4.8 %, 33.28 ± 4.62 % and 3.81 ± 0.07, respective-

ly (A.M. Krüger unpublished data).

The values obtained using the direct method indicated

that there was considerable variation in how well the

material was compacted in the silos, which can be related

to the method of compaction used, the stage of growth of

the forage when ensiled, the moisture content of the

forage at ensiling, etc. According to Jobim et al. (2007),

although there is no optimal value for silage density,

values in the range of 550‒850 kg NM/m³ are most

suitable, and these are obtained only under favorable

conditions. Typically, appropriate compression for

desirable fermentative characteristics and minimal losses

in maize silage is obtained with minimum SMDM around

225 kg DM/m³. The majority of the silages sampled were

above this minimum level. One might expect that the

nutritional value and acceptability of the silage to

Figure 3. Relationship between SMNM (specific mass based

on natural matter), expressed in kg/m³ and resistance to

livestock would also vary markedly.

penetrometer metallic cone, expressed in MPa.

The penetration resistance observed when employing

the indirect method indicates that, while there was marked

variation in density of the silage as measured directly,

there was much greater variation in resistance as

measured by the penetrometer. If one assumes that the

density measurements were accurate, one might question

the accuracy of the penetrometer readings for the same

silages.

In an experiment in which 18 penetrometer measures

were performed in one silage sample kept under

controlled conditions in an experimental station, Silva

et al. (2011) found a mean penetrometer resistance of

1.09 ± 0.23 MPa and specific mass observed based on dry

matter of 170 ± 36.5 kg DM/m³. As in the present study,

resistance values obtained were compared with direct

measurements as well.

The results obtained for SM (Table 1) observed (direct

method) and estimated (indirect method), both for NM

Figure 4. Relationship between SMDM (specific mass based

and DM, are consistent with those typically observed in

on dry matter), expressed in kg/m³ and resistance to

farm silos and the values found by the indirect method

penetrometer metallic cone, expressed in MPa.

presented a smaller range of variation when compared

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

98 A.M. Krüger, C.C. Jobim, I.Q. de Carvalho and J.G. Moro

with the direct method, because regression equations

silages with SMDM above 260 kg DM/m3 had DM % in

determine the middle pathway and reduce the effect of

the range 325‒391 g DM/kg. All silages with penetro-

outlying values. There was a positive relationship

meter readings below 0.75 MPa had DM % below 300 g

between the SM of silage and penetration resistance to the

DM/kg and SMDM below 230 kg DM/m3. The relation-

metal cone (Figures 3 and 4). This was a curvilinear

ship between DM concentration in silage and reliability

relationship with silage SM increasing as the resistance to

of the machine needs to be investigated further to confirm

the cone penetration increased to a peak of about 900 kg

these findings.

NM/m3 or 300 kg DM/m3.

Silva et al. (2011) observed a positive linear

Acknowledgments

relationship between the SM of maize silage and

penetration resistance to the metal cone in 2 experiments.

The authors thank CNPq (National Council for Research

However, in 1 of the experiments, the adjusted linear

and Technological Development) for the financial

equation had a low coefficient of determination,

support.

explaining only 33% of the observed variation. This low

coefficient was attributed to surface conformations of

References

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lower compression of the ensiled material, and altered the

Craig PH; Roth G. 2005. Penn State University bunker silo

density study summary report 2004–2005. Department of

physical correlation of mass and volume, which may have

Agriculture, and Pennsylvania Counties Cooperating, Penn

influenced the relationship between SM of silage and

State University, Dauphin, PA, USA. p. 1‒9. https://goo.gl/

penetration resistance to the metal cone. In order to

9Bp6qY

correct this, they developed equations based on the

D’amours L; Savoie P. 2005. Density profile of corn silage in

stratum in which each measurement was taken.

bunker silos. Canadian Biosystems Engineering 47:2.21‒

Those authors observed that the SM estimation with

2.28. https://goo.gl/qLmluM

the penetrometer had greater accuracy when expressed as

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SMNM rather than as SMDM, while in our study the SM

SO; Almeida BG. 2011. Improvement of a testing apparatus

estimated with the indirect method showed greater

for dynamometry: Procedures for penetrometry and

accuracy when expressed as SMDM (R² = 0.80) rather

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aggregates. Revista Brasileira de Ciência do Solo 35:373‒

than as SMNM (R² = 0.57). The differences between the

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factors that may affect silage in silos on different farms

densities. University of Wisconsin, Madison, WI, USA. p.

(the study of Silva et al. 2011 was conducted under

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controlled conditions on an experimental station); also,

Jobim CC; Nussio LG; Reis RA; Schmidt P. 2007. Avanços

the penetrometer used in the above-mentioned study was

metodológicos na avaliação da qualidade da forragem

a different model from the one we used.

conservada. Revista Brasileira de Zootecnia 36:101‒119.

After corrections considering silage stratum, Silva et

DOI: 10.1590/S1516-35982007001000013

al. (2011) found R² = 0.86 between the observed and

Nussio LG; Campos FP; Dias FN. 2001. Importância da

estimated SMNM and R² = 0.82 between observed and

qualidade da porção vegetativa no valor alimentício da

silagem de milho. Proceedings of the Simpósio sobre

estimated SMDM. Both Silva et al. (2011) and Vissers et

produção e utilização de forragens conservadas, Maringá,

al. (2007) concluded that the penetrometer is a reliable

2001. Vol. 1:127‒145. https://goo.gl/qik6JV

indirect method for determining the SM of maize silage.

Silva MS; Jobim CC; Tormena CA; Calixto Jr. M; Soriane

Our work confirms this conclusion and in addition

Filho JL; Roman J. 2011. Determinação da massa específica

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that can be used on farm. The regression equation

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y = -82.109x² + 257.9x + 89.182 (R² = 0.80) we developed

Storck L; Kobata SGK; Brum B; Soares AB; Modolo AJ;

for estimating SMDM using this penetrometer provided

Assmann TS. 2016. Sampling plan for using a motorized

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Brasileira de Engenharia Agrícola e Ambiental 20:250‒255.

DOI: 10.1590/1807-1929/agriambi.v20n3p250-255

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data suggest that penetrometer measurements above 1.0

C; Cheng Q; Sun W. 2010. An improved penetrometer

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DM/m3. However, more testing would be needed to

Engineering 105:273‒277. DOI: 10.1016/j.biosystemseng.

confirm this rule of thumb. It was of interest that all

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JMG. 2007. Concentrations of butyric acid bacteria spores

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jds.S0022-0302(07)71576-X

(Received for publication 31 August 2016; accepted 22 February 2017; published 31 May 2017)

© 2017

Tropical Grasslands-Forrajes Tropicales is an open-access journal published by Centro Internacional de Agricultura Tropical (CIAT). This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported license. To view a copy of this license, visit

http://creativecommons.org/licenses/by-nc-sa/3.0/

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

Tropical Grasslands-Forrajes Tropicales (2017) Vol. 5(2):100102 100

DOI: 10.17138/TGFT(5)100-102

Book Review

Tropical forage legumes: Harnessing the

potential of Desmanthus and other genera

for heavy clay soils

Edited by JOHN R. LAZIER and NAZEER AHMAD.

Published by CABI Publishing, Wallingford, UK, 2016.

480 pp. Price US$ 225.00. ISBN 9781780646282.

DOI: 10.1079/9781780646282.0000

Over 200 years ago, Thomas Jefferson, principal author

any new species to be invasive, both within and outside

of the American Declaration of Independence and the

the various regions in which they may be seen to have

third President of the USA, also a philosopher and farmer,

agronomic and economic merit (Williams and Burt

wrote: “The greatest service which can be rendered any

1982)”.

country is to add an useful plant to its culture”. This book,

The book describes the process followed by Dr. Burt,

“Tropical forage legumes”, highlights the complexity of

his co-authors and others to expand the range of legumes

the process in domesticating species, and the remarkable

available for use on heavy clay soils in the tropics, using

work of one person in particular, Dr. Robert (Bob) L.

the range of soils and climates found in Belize and

Burt, in adding a useful plant to our culture.

northern Australia as examples. Commendably, they did

The book itself has a somewhat poignant background,

not feel constrained by the prevailing dogma that would

in that two of the initial authors, Dr. Burt and Professor

have limited them to a particular group of already

Nazeer Ahmad, died before the book was published.

recognized forage legume genera, including Desmodium,

Dr. Lazier, himself a scientist of note, and also a friend

Macroptilium and Stylosanthes, many of which had been

and colleague of both great professionals, persisted with

selected for acidic soils in the subtropics . The book

the submission out of friendship and the recognition

comprises a total of 19 chapters, largely written as journal

of the need to make the information available to others

papers with Abstract, Introduction, Materials and

working in this general field. Dr. Lazier writes: “Since

Methods, Results, Discussion and Conclusions.

this research was undertaken there has been a marked

The first 9 chapters by various combinations of Burt,

decline in the funding for such research, and with the

Lazier and Ahmad covered all aspects of the work, from

retirement of experienced researchers much of this

collection of wild-type legumes in the Yucatán Peninsula

information will be lost. This volume has been written

region of Belize, Guatemala and Mexico, as well as in the

in order that new scientists in this field will not be

Caribbean islands, to the very involved methodology of

repeating work which has already been done, and can

identifying appropriate genotypes for evaluation, and

build upon the results. Recommendations are provided

ultimately to the evaluation programs in Belize and

for further research.” Recurrent themes are that: many

Australia. While much of the statistical methodology

areas of legume species diversity remain uncollected;

might have limited appeal to many readers, the actual

potentially valuable genetic material is being lost

philosophy and techniques involved in the distillation

through global warming and increasing agricultural and

process, together with the range of genotypes

urban development; and there is an urgent need to

investigated, will have broader appeal. The authors make

conserve remaining material before it is lost completely.

the point: “It follows that if genetic material is to be

It was gratifying to note that the authors favored a

selected for trials, for use as ‘core collection’, or

responsible approach to plant introduction, particularly in

‘representative range’, it cannot be done solely on the

relation to weediness. “Attempts to meet this demand

basis of geographic or provenance data. A meaningful

(adapted legumes) have, in fact, been made for some time,

classification is required.” Krull and Borlaug made a

with the due regard that must be paid to the potential of

similar observation in 1970: “The major hurdle to

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

101

unlocking the secrets (of our genetic resource collections)

necessary to ensure seed production would not be a

has been our inability to classify the variability.” Various

constraint to release and adoption, and to address other

approaches to overcome this hurdle are proposed and

issues such as establishment, plant nutrition, nodulation

discussed.

and management. Once again, Desmanthus was identi-

The research homes in on two species groups in

fied as a source of adapted germplasm for pasture, along

particular, Stylosanthes hamata and Desmanthus spp.,

with another of the species discussed by Burt, initially

although a number of other species are put forward as

known as Stylosanthes sp. aff. scabra and subsequently as

being worthy of further evaluation. It should be remem-

S. seabrana. While traditional species such as Lablab

bered that the reported work was conducted in the 1970s

purpureus were unsurprisingly successful for short-term

and 80s, and results and discussion need to be interpreted

leys, two species, which had been rejected from earlier

in terms of the state of knowledge at that time. It is

evaluations in favor of more persistent species, found a

interesting to note that a number of species identified in

significant role in ley pastures on clay soils – Clitoria

the various studies reported have subsequently been

ternatea and Macroptilium bracteatum.

absorbed into international tropical agricultural systems,

The aim of plant evaluation is to bring new and useful

often as a direct or indirect consequence of the work. As

germplasm into our culture, whether it be for immediate

well as Stylosanthes hamata and Desmanthus spp. in

use by humans or livestock, or to inject a measure of

grazing systems, Desmodium cinereum (long known

sustainability into current management or production

incorrectly as Desmodium rensonii), which they flagged

systems. On this basis, Chapter 11 provides an interesting

as a species of interest, is widely used in legume

case study of how Dr. Chris Gardiner from the James

hedgerows in Southeast Asia for erosion control and live-

Cook University, Townsville, Queensland, capitalized on

stock feed. Calopogonium caeruleum and Centrosema

Dr. Burt’s earlier work in the northern part of the State,

plumieri, considered as having forage potential, have

by visiting the evaluation sites established in the 1980s,

been rejected in this role due to low palatability, but are

and collecting and identifying legume species, largely

successfully used as green manure cover crops under

Desmanthus, persisting in this particularly testing

plantations. The Australian experience with the shrub,

environment – heavy clay soils and low, unreliable annual

Codariocalyx gyroides, was similar to that in Belize; it is

rainfall. This means he started with genotypes that had

very palatable but brittle and fails to persist under grazing.

persisted for around 20 years under commercial

The ubiquitous creeping legume, Desmodium incanum,

management in the target environment. Drs. Burt and

has not been adopted commercially despite being

Lazier had already done the painstaking work of selecting

promoted as a grazing legume (Kaimi clover) in Hawaii

genetic material that had a good chance of performing

as early as the 1940s. The mimosoid shrub/small tree,

well in this environment. In the ensuing period, Dr.

Acacia angustissima, attracted some attention in

Gardiner and others have undertaken a range of studies to

Australia, but was found to be unpalatable and showed the

evaluate the most promising varieties, and to define

potential to become an environmental weed.

aspects of their agronomy and productivity necessary to

Chapter 10 by Dr. Kendrick Cox from the Department

proceed to commercial release through a partnership with

of Agriculture and Fisheries, Queensland, summarizes the

a private company. Accordingly, a mixture of 5

significant volume of work carried out in Queensland,

Desmanthus selections (three of D. virgatus and one each

Australia, seeking legumes to fulfil a range of roles on

of D. leptophyllus and D. bicornutus) is being made

alkaline clay soils, mostly in the subhumid and semi-arid

available to producers under the Progardes trade mark.

areas in central and southern parts of the State. Most of

This chapter highlights the value of returning to

the previous work focused on selecting grazing legumes

discontinued evaluation sites if persistence is one of the

for the acidic infertile soils of the more humid coastal

key criteria of merit in selecting useful genotypes, and

strip. The research covered in this chapter had two

conversely demonstrates the folly of expecting to select

primary purposes: (1) to identify legumes to supplement

persistent plants from short-term experiments.

the limited suite of species that could be used in pasture

In the final chapters, Dr. Lazier focuses again on the

leys to build up the level of labile soil nitrogen in

situation in Belize, a small country of only 23,000 km2,

preparation for subsequent cropping; and (2) to identify

about 1/5 the size of neighbouring Guatemala. He

legumes that could persist in pastures, particularly the

initially outlines the development of the beef industry in

large areas of buffel grass ( Cenchrus ciliaris) that were

the country, identifying constraints to its expansion, one

becoming less productive as nitrogen became increasing-

being limited forage development. He follows up the

ly bound up in the extensive fibrous root system of the

industry review with an analysis of native pastures, in

grass. Within each of these, additional research was

terms of both botanical and chemical composition, and

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)

102

finally a series of experiments comparing the more

should be A. pintoi. There are other name changes and

productive native legumes with a range of exotic species.

misspellings in the book, but it is not the role of a reviewer

As in the earlier chapters, Dr. Lazier’s work provides a

to act as proof reader. These are mentioned merely to

roadmap of how researchers can approach a forage

draw the reader’s attention to the issue, in order to prevent

development program in an untested area. As with any

perpetuation of incorrectly spelled names.

roadmap, there are usually a number of ways to reach

This is not a text. It is a book that will appeal to people

one’s destination. It is now over 40 years since he

involved in the search for new species to play a role in the

commenced his work in Belize, in which time alternative

development of sustainable agricultural production

methodologies have been developed for evaluating plants,

systems. While it focuses on legumes for alkaline clay

which may have produced slightly different outcomes,

soils, potential readership should not be limited to those

partly through using different comparators, but also

interested solely in legumes or alkaline clay soils. There

through using non-destructive sampling.

are many facets to this publication – legume species, soil

A note of caution – some of the species names used in

chemistry, plant ecology, field and statistical method-

the book are those that would have been applied in the

ology, seed production and philosophy, not to mention a

1970s. Although many appear to have been brought into

brilliant bibliography. Even the multitude of tables, that

line with the currently accepted taxonomy, some have not,

some may find tedious, provide detail for others that

e.g. the common centro mentioned in the book is listed as

might not be available elsewhere. I cannot in all honesty

Centrosema pubescens but is now accepted as C. molle,

say that this is a book that should grace the shelves of

while C. pubescens is now applied to cv. Belalto; many

every student of leguminology, but it should be consider-

former Cassia spp. are now classified as Chamaecrista or

ed a must for libraries associated with agricultural R & D

Senna; Macroptilium longepedunculatum is now

agencies around the world in both the tropics and

accepted as M. gracile; the Arachis pusilla referred to was

subtropics.

actually misnamed in the Australian collection, and

should be Arachis triseminata. There are misspelt names

such as Desmodium cinerium, which should be

Bruce G. Cook

Desmodium cinereum, Stylosanthes sympodiales, which

Agricultural consultant (former Research Agronomist)

should be S. sympodialis, and Arachis pintoii, which

Westlake, Qld, Australia

(Published 31 May 2017)

© 2017

Tropical Grasslands-Forrajes Tropicales is an open-access journal published by Centro Internacional de Agricultura Tropical (CIAT). This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported license. To view a copy of this license, visit

http://creativecommons.org/licenses/by-nc-sa/3.0/

Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)