Leucaena feeding systems in India

Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.Since its introduction to India in 1976 Leucaena leucocephala ssp. glabrata has spread rapidly, especially in the last couple of decades, mainly due to its use as either firewood or pulpwood. Use of its foliage for feeding livestock has been mainly a by-product of this activity. The foliage is highly nutritious because it has high protein concentration and good palatability, and the tree can withstand repeated defoliation. Research carried out by Indian scientists on leucaena has focused on mainly agronomic management, agroforestry studies of mixed cropping systems, mimosine toxicity, germplasm testing and economic evaluation. Feeding leucaena has had a positive impact on the dairy industry in particular. It is rarely purchased for fodder and is usually poached by smallholders from existing plantations, most of which are established by animal rearers for their own purposes. More widespread use of leucaena for fodder could be achieved in India by introducing varieties with either reduced seed production or sterile ones, which can be easily propagated vegetatively. In addition, psyllid resistance, suitable mechanized harvesting methods and training livestock owners in proper management of leucaena trees should help in making this high quality fodder more popular in India.

Environmental adaptation of leucaena in Western Australia – challenges and opportunities

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.

Sterile leucaena becomes a reality?

Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.A research program to develop sterile leucaena has commenced to enhance red-meat production in additional regions of Australia including Western Australia, Northern Territory and New South Wales, where growing seeded leucaena is not currently permitted or encouraged. In this study we report on the development of methodology using a mutagenizing agent, EMS (ethyl methanesulfonate), to cause mutations in the self-fertile commercial leucaena cultivar, Redlands. Several experiments to determine the optimum rate of EMS have been completed and first generation mutagenized plants (M0) established in the field at Redlands Research Station, Cleveland, Queensland, Australia. An EMS concentration of 0.35% applied to germination paper proved the best method to achieve a target emergence percentage of 50%. To date, 27 of 179 mutagenized M0 seedless plants are considered to be putatively sterile. A further 1,200 M0 plants have been established in the field providing an even greater chance of identifying sterile leucaena plants with the desired forage quality and psyllid-resistance attributes.