Establishment of Leucaena leucocephala cv. Tarramba in eastern Indonesia

The adaptability and productive value of Leucaena leucocephala cv. Tarramba (Tarramba) in eastern Indonesia has been observed since 2001 (Nulik et al. 2004), with many farmers and other stakeholders currently requesting seed for planting. Tarramba has greater forage and timber production, and psyllid tolerance than other commercial cultivars and locally grown leucaena. The variability of soils and climate in eastern Indonesia means that establishment techniques specific to the region are required to achieve maximum adoption and utilisation of Tarramba.


Introduction
The adaptability and productive value of Leucaena leucocephala cv.Tarramba (Tarramba) in eastern Indonesia has been observed since 2001 (Nulik et al. 2004), with many farmers and other stakeholders currently requesting seed for planting.Tarramba has greater forage and timber production, and psyllid tolerance than other commercial cultivars and locally grown leucaena.The variability of soils and climate in eastern Indonesia means that establishment techniques specific to the region are required to achieve maximum adoption and utilization of Tarramba.

Materials and Methods
A number of sites differing in soil type in west Timor (8 sites) and east Sumba (4 sites) were selected to study the establishment of Tarramba (Table 1).Management varied among sites for factors such as exclusion of animals during establishment and competition from weeds and trees.Scarified seed (imported from Australia) was washed and immersed in clean water until the seed became imbibed (4−12 hours).The seed was germinated in petri-dishes (radicle length between 0.5 and 1.5 cm) and sown into polybags (December 2011) or directly seeded into the field between the rows, when planting maize.
Seedlings in polybags were well watered and pressed to prevent soil loss and wilting during transplanting to the field in January and February 2012.Plant height ___________ Correspondence: Jacob Nulik, BPTP, NTT, Jl.Timor Raya km 32, Naibonat, Kupang, East Nusa Tenggara, Indonesia.Email: jacob_nulik@yahoo.com and basal stem diameter were measured to determine yield via a growth index (GI) (GI = height x basal diameter 2 ) (Stewart et al. 1992).Fifty plants from each site were identified for measurements.Mean GI data presented here are from a single measurement in October 2012.Young fully expanded leaves were collected from leucaena trees established at the Kambatatana sites in east Sumba to identify nutrient deficiencies, as the soils were highly eroded, poor karst limestone soils.

Results and Discussion
As anticipated, Tarramba performed differently according to method of planting and the environmental conditions and management during establishment.Soil type (particularly water holding capacity and fertility) and competition from weeds and shading affected the capacity of the plants to grow to their potential (Table 1).Plant growth was greatest in vertisols and alluvial sediments, such as at Batulesa in Kupang District and at Wanga in east Sumba, followed by Ponain on a vertisol, then Tesbatan II and Oebola Dalam on alfisols, with poorest growth during establishment on poor karst limestone soils in Kambatatana and at Naunu, where competition from weeds and trees was high.Tissue analysis of leaf samples (youngest fully expanded leaves) indicated that there were deficiencies of P, K and S in samples taken from one or both Kambatatana sites (Ruaysoongnern et al. 1989;Mullen et al. 2003) (Table 2).Nevertheless, the nutritional value of Tarramba was superior to that of the native grasses present at Kambatatana, particularly in crude protein concentration (19% vs <3%).
Best seedling growth occurred at sites that involved transplanted seedlings from polybags, which allowed plants to establish for 2 months with daily watering without competition from trees or weeds, e.g. at the Batulesa and Wanga sites (GI>4000), with Ponain the next best site (GI = 1500).Transplant sites that were not well weeded did poorly (GI of Tesbatan 1 was 198).Establishment by direct seeding was best where competition from trees was minimized, e.g.GI at Oebola Dalam was 1180.Direct seeding of imbibed seeds into maize rows was best with good weed management, although competition from actively growing maize was initially high.This planting method provided excellent growth conditions (sufficient soil moisture content and low competition) following harvest of the maize.(Ruaysoongnern et al. 1989;Mullen et al. 2003).

Conclusions
This study has shown that Leucaena leucocephala cv.Tarramba can be established successfully in easternIndonesia, when seed is prepared appropriately for germination, seedlings are allowed to establish without grazing, and competition from weeds and trees is minimal.Transplanting from polybags will give better initial growth than direct seeding, even into well weeded maize.Despite reduced plant growth in karst limestone soils owing to nutrient deficiencies, the forage produced is of better quality than existing native grasses even in the dry season.This cultivar shows great potential for improving livestock performance in eastern Indonesia regardless of soil type.

Table 1 .
Site description, management practices and Tarramba growth index (± standard deviation).

Table 2 .
Nutrient concentrations in young fully expanded leaves of leucaena plants harvested November 24, 2012.