Resistance to Phomopsis stem and pod blight of narrow-leafed lupin in a range of environments and its association with reduced Phomopsis seed infection.

Abstract

Resistance to Phomopsis stem and pod blight, caused by Phomopsis leptostromiformis (Knhn) Bubak, in narrow-leafed lupin (Lupinus angustifolius L.) was consistently expressed at 5 sites in the southwest of Western Australia and 5 sites in south-eastern Australia in 1984. There was a high correlation (r = 0.95, P< 0.001) of mean Phomopsis stem ratings on the 8 breeding lines and 2 cultivars between the 2 regions of southern Australia. The mean frequency of seed infection by P. leptostromiformis in 6 resistant lines in Western Australia ranged from 0.1 to 1.0% compared with 1.4% in 75A65-5 (a line with intermediate resistance) and 2.0% in Yandee and Chittick (susceptible cultivars). In south-eastern Australia, mean seed infection in 6 resistant lines ranged from 0.0-0.6% compared with 2.3% in 75A65-5, 1.6% in Yandee, and 1.1% in Chittick. There was also a correlation (r = 0.73, P < 0.05) of mean seed infection levels in the 8 lines and 2 cultivars between the regions. Pod blight occurred at significantly lower frequency in resistant lines than in susceptible cultivars at 3 sites in Western Australia where pod lesions were visible. Correlations among Phomopsis stem ratings, pod blight severity, and the frequency of seed infection among lines and cultivars were significantly positive in all comparisons at individual sites and when averaged across the 2 regions of southern Australia.