Abstract:
Grain and forage production of six accessions (Rongai, Highworth, T58/ 13, CPI 3 1 1 13, CPI 41 222 and CPI 60 216) of lablab bean (Lablab purpureus) were measured over two seasons in the Ord Irrigation Area. All accessions were quantitative short day plants, flowering during the early dry season (May-July). Forage yields at flowering were generally unaffected by sowing date for sowings made between December and February, but declined with later sowings. There were marked differences between accessions in the forage yield at flowering, and the peak yield of 8.6 t/ha was obtained with a December sowing of accessions T58/ 13; this comprised 3.6 t/ha of leaf containing 3.7% nitrogen and 5.0 t/ha of stem containing 1.1 % nitrogen. The uptake of nitrogen by the tops between sowing and flowering ranged up to 1.8 kg/ha.d (1 94 kg N in 108 days) indicating the potential value of lablab as a green manure crop. Grain yields ranged from 0.27 to 3.05 t/ha over all sowing dates and accessions with the peak yield being obtained in a February sowing of cv. Highworth. All accessions became smaller and bushier as sowing was delayed. This facilitated harvesting for grain. Cutting and removal of foliage at the onset of flowering led to rapid regrowth and renewed flowering, and gave grain yields up to 90% of those obtained from undefoliated treatments. The cultivar Highworth was best for grain production and for dual purpose forage and grain production.