Comparison of lupin varieties for grain yield, nutritive value of stubbles, incidence of infection with Phomopsis leptostromiformis and occurrence of lupinosis

Abstract

The lupin cultivars Borre, Uniwhite, Fest, Uniharvest, Weiko III, CB46 and Ultra were grown for two years at Baker's Hill, Western Australia (640 mm average rainfall). Fest gave the highest grain yield in both years but the ranking of the other cultivars differed in the two years. Grain lost at harvest varied from 24 to 860 kg ha-1, being significantly higher from Weiko Ill and CB46. The nitrogen content of the grain of Weiko III and Ultra was significanlty higher than that in all other cultivars, and the pods of Ultra had a higher nitrogen content than pods of any other cultivar. In both years the stems and pods of Weiko Ill and Ultra had significantly lower concentrations of soluble carbohydrates, the stems fewer lesions from Phomopsis, and the sheep grazing the stubbles a much lower and less severe incidence of lupinosis than on all the other cultivars. In the first year liveweight gains over 63 days ranged from 2.9 kg on Fest to 7.5 kg on Borre. In the second year, when lupinosis was severe, there was a positive correlation between its severity and concentration of copper in the liver, and a negative correlation with zinc concentration. In another experiment Ultra and Unicrop had fewer Phomopsis lesions than CB46 and sheep grazing the stubbles less liver damage. Dry ewes grazed on stubbles of Uniharvest lupins planted at three different dates and on Fest lupins barely maintained weight but those grazed on wheat stubble lost 6.5 kg in 42 days. Stubbles from Uniharvest lupins sown at four different dates in two years all produced lupinosis when fed to sheep in pens. The diet selected by sheep from the stubbles was measured in two of the experiments. In both, stem, which is the most toxic fraction, made up at least 80 per cent of the diet from the time grazing started.