Offered Papers Theme A: Efficient Production from Grassland
Description
Production of the valuable fodder tree legume Leucaena leucocephala (leucaena) is limited to the subhumid (600-800 mm annual rainfall) areas of northern Australia by the psyllid insect pest Heteropsylla cubana. Defoliation caused by severe psyllid infestations can suppress forage yields of commercial leucaena varieties by 50-80%. Susceptibility to psyllid damage is a major impediment to grazier adoption of leucaena pastures in the more humid tropical areas of Australia. A comprehensive international agronomic evaluation of the entire Leucaena genus (Mullen et al., 2003) revealed that the artificial interspecific F1 hybrid of L. pallida x L. leucocephala ssp. glabrata (called KX2) had a high degree of psyllid resistance, excellent vigour and broad environmental adaptation. The KX2 F1 hybrid also had superior forage quality compared to other psylli-resistant taxa, such as L. pallida, L. trichandra and L. diversifolia. Commercial utilization of the KX2 F1 hybrid by Australian graziers has been prevented by a lack of planting material. To date, seed production of the F1 hybrid has only been possible by laborious hand pollination. The KX2 F1 hybrid has been successfully vegetatively propagated for smallholders in SE Asia, however cloned cuttings are expensive to produce and are not suited to broad acre leucaena planting in Australia. A recurrent selection breeding program was initiated to produce a genetically stable, advanced generation KX2 hybrid that breeds true-to-type and is suitable for commercial release. We anticipate that 4 cycles of selection will be required to achieve this objective. This paper reports the agronomic evaluation of the KX2 F2 generation.
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Breeding a Psyllid-Resistant Interspecific Hybrid Leucaena for Beef Cattle Production in Northern Australia
Production of the valuable fodder tree legume Leucaena leucocephala (leucaena) is limited to the subhumid (600-800 mm annual rainfall) areas of northern Australia by the psyllid insect pest Heteropsylla cubana. Defoliation caused by severe psyllid infestations can suppress forage yields of commercial leucaena varieties by 50-80%. Susceptibility to psyllid damage is a major impediment to grazier adoption of leucaena pastures in the more humid tropical areas of Australia. A comprehensive international agronomic evaluation of the entire Leucaena genus (Mullen et al., 2003) revealed that the artificial interspecific F1 hybrid of L. pallida x L. leucocephala ssp. glabrata (called KX2) had a high degree of psyllid resistance, excellent vigour and broad environmental adaptation. The KX2 F1 hybrid also had superior forage quality compared to other psylli-resistant taxa, such as L. pallida, L. trichandra and L. diversifolia. Commercial utilization of the KX2 F1 hybrid by Australian graziers has been prevented by a lack of planting material. To date, seed production of the F1 hybrid has only been possible by laborious hand pollination. The KX2 F1 hybrid has been successfully vegetatively propagated for smallholders in SE Asia, however cloned cuttings are expensive to produce and are not suited to broad acre leucaena planting in Australia. A recurrent selection breeding program was initiated to produce a genetically stable, advanced generation KX2 hybrid that breeds true-to-type and is suitable for commercial release. We anticipate that 4 cycles of selection will be required to achieve this objective. This paper reports the agronomic evaluation of the KX2 F2 generation.
