Tropical Grasslands-Forrajes Tropicales

Agronomic performance of six accessions of forage peanuts (Arachis pintoi) in the Northeast Antioquia subregion, Colombia

2024-09-03T20:57:16+00:00

This evaluated the agronomic performance of six accessions of forage peanuts (Arachis pintoi) in the Northeast of Antioquia, Colombia. The evaluation was conducted at the El Nus Research Center of Agrosavia, in San José del Nus, Antioquia, Colombia. A split-plot in time design, with four blocks was used. Treatments were defined by the combination of six accessions, four cutting frequencies and two seasons. A mixed model that considered accession, cutting frequency, season, and the interaction among those factors as fixed effects, and the block as a random factor was used for data analysis. Between June 2021 and February 2023, agronomic variables (dry matter yield, plant height, and coverage), morphological characteristics (stem diameter, length and number of stolons, and leaf with and length) and nutritional quality (PC, FDN, FDA, and DIVMS) were evaluated. Accessions and seasons affected (P<0.05) the dry matter yield and morphological characteristics. Differences due to accessions and cutting frequency were detected for PC, FDA, and DIVMS. Plant coverage was the only variable affected (P<0.05) by the triple interaction (accession × cutting frequency × season). The results obtained confirm variability among the accessions of A. pintoi evaluated, in terms of production and nutritional quality. Accession CIAT 22160 stood out as promising for the hillside areas of Northeastern Antioquia and deserves further evaluation for of animal responses at farm level.

Protected urea as a nitrogen source for Mulato II grass: impacts on forage production, feed value and composition

2025-03-04T08:15:38+00:00

The growing demand for high-yielding forage cultivars with drought tolerance, broad environmental adaptation and sustained feed quality has stimulated the development of new Urochloa (syn. Brachiaria) genotypes, such as Mulato II. Efficient nitrogen (N) fertilization strategies are essential to optimize their productivity and nutritional value. This study aimed to evaluate the effects of N fertilization, using conventional and protected urea at 0, 50, 100 and 150 kg N/ha on green mass production (GMP), dry matter production (DMP), leaf:stem ratio (LSR), nutritional value, apparent nitrogen recovery (ANR), apparent nitrogen conversion efficiency (ANCE), and crude protein yield per hectare (CP/ha) of Mulato II. The experiment followed a completely randomized 4 × 2 factorial design. The results showed that the N source significantly affected GMP, DMP, neutral detergent fiber (NDF) during the second growth period, and ANCE. Increasing N rates led to higher GMP, DMP and CP concentration, while decreasing ANCE. Fertilization with protected urea improved ANCE and reduced NDF concentration, indicating greater efficiency in nitrogen utilization. These findings support the strategic use of protected urea at moderate N rates to enhance forage productivity and nitrogen use efficiency in Mulato II.

Herbicide sensitivity of desmanthus (Desmanthus virgatus) at different stages of development

2025-05-12T09:32:35+00:00

Desmanthus (Desmanthus spp.) is a native, naturalised or sown legume in many tropical and subtropical areas, including Australia where its potential use as a companion legume is extending to more southern latitudes. Desmanthus pastures are commonly sown into former cropping paddocks which have a significant weed burden. In these situations, weeds can be an issue during the establishment phase as well as in established desmanthus pastures. Three field experiments were conducted in northern New South Wales to assess the sensitivity of D. virgatus ‘Marc’ to herbicides at different stages of pasture development. At sowing, imazethapyr [0.41 kg active ingredient (a.i./ha)] and triﬂuralin (0.85 kg a.i./ha) were suitable for pre-emergent use. In a 9-week-old seedling pasture, bromoxynil (0.14–0.56 kg a.i./ha) and flumetsulam (0.02–0.08 kg a.i./ha) caused little plant damage and are suitable for use, while 2,4-D amine (0.54–2.16 kg a.i./ha) and MCPA (0.49–1.95 kg a.i./ha) caused extensive damage, reducing herbage production and delaying flowering. In a 10-month-old established pasture, bromoxynil (0.14–0.56 kg a.i./ha), imazethapyr (0.04–0.14 kg a.i./ha) and terbuthylazine (0.44–1.75 kg a.i./ha) caused minor short-term plant damage. Isoxaflutole (0.04–0.15 kg a.i./ha) resulted in temporary plant foliage bleaching and reduced production, without on-going effects following cutting. Established plants of desmanthus were defoliated by paraquat (0.2–0.8 kg a.i./ha) but regrew without phytotoxic effects. All these herbicides could be used on desmanthus plants. In established desmanthus pastures 2,4-DB (0.35–1.4 kg a.i./ha) caused significant damage but not plant death. There were no ongoing effects of the herbicide on plant productivity following cutting.

The use of ethephon for improving shoot development of buds from different positions of BRS Capiaçú elephant grass culms

2024-02-14T06:50:56+00:00

Use of ethephon on buds from different positions on the culm of BRS Capiaçú elephant grass was evaluated to improve development of shoots during planting. The experiment compared buds originating from the apex and base of the BRS Capiaçú culm without ethephon application, cut culms with buds immersed for 1 min in ethephon solution (0.650 L ethephon/ha) and application of 150 L ethephon/ha directly on the bud on the standing culm. The position of the bud in the culm and the application of ethephon positively influenced the development and gaseous exchange of BRS Capiaçú. Buds immersed for 1 min in ephethon showed better development, CO₂ assimilation rate (A), transpiration (E) and stomatal conductance. Plants growing from buds from the base of the culm produced more leaves, with higher biomass and higher transpiration, It is recommended to use buds from the base of the BRS Capiaçú culm for propagation when using ethephon.