Environmental adaptation of leucaena in Western Australia – challenges and opportunities

Abstract

Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia. There is considerable interest from Western Australian (WA) pastoralists on the potential role of leucaena (Leucaena leucocephala) in northern WA, where the potential area for dryland production of species of the genus Leucaena is high. Although it is highly regarded for animal production in other countries and in Queensland, leucaena is a contentious species since its status as an environmental weed precludes it from use on pastoral leases in the Kimberley and Pilbara regions of WA. Development of sterile/seedless forms would overcome risks of spread of the species as a weed. The key environmental constraints to growth of leucaena are likely to be the length of the dry season and low fertility of most soils other than the grey/black cracking clays (vertosols). Psyllid resistance and cool temperature tolerance are likely to be of secondary importance. Opportunities for irrigated production are also emerging and may allow leucaena species to be used in environments previously considered well outside their home-range. It is desirable now to re-examine the diversity of the wider leucaena genus for adaptation to WA conditions generally and for the purpose of selecting elite parent material for use in a sterile/seedless leucaena breeding program. These perennial species that can be under production for 30 to 40 years need to be evaluated in the target environments for at least 3‒5 years to fully understand their potential as adult plants.