Volume 25, 119

Tropical Grasslands (1991) Volume 25, 119–128

Sustaining productive pastures in the tropics
7. Tree and shrub legumes in improved pastures

H.M. SHELTON¹, J.B. LOWRY², R.C. GUTTERIDGE¹, R.A. BRAY³and J.H. WILDIN⁴

¹Department of Agriculture, The University of Queensland, St. Lucia;
²Division of Tropical Animal Production, CSIRO, Townsville;
³Division of Tropical Crops and Pastures, CSIRO, St. Lucia; and
⁴Agriculture Branch, QDPI, Rockhampton; Queensland, Australia.

Abstract

Among tropical legumes, the tree species, Leucaena leucocephala, has demonstrated a high potential for increasing liveweight gain. Expansion of its use is limited by damage from the psyllid (Heteropsylla cubana) and the slow rate of establishment of leucaena seedlings in some environments. These problems with L. leucocephala have given impetus to the search for alternative varieties and species of tree legumes with similar features. These features include longevity and versatility of management once established, high animal production potential, tolerance of a wide range of climatic and edaphic environments, and potential for use in a range of agroforestry applications because of their deep rooted habit. The shading effect of tree canopies can have a positive effect on understorey grass yield and quality due to improved nutrient cycling.
There is potential for selection of higher yield, improved psyllid and cool temperature tolerance within the Leucaena genus. Other promising genera of tree legumes include Calliandra, Gliricidia, Albizia and Sesbania. However, there are problems of lower nutritive value and acceptance in some of these genera and further evaluation is required. Also it is not known how well these other tree legumes can tolerate direct grazing.
The future acceptance of tree legumes by graziers will depend on the improved availability of suitable germplasm, a practical knowledge of their establishment and management requirements, and a clear demonstration of their potential economic benefits.