Inheritance of resistance to early blight disease in a diploid potato population

Early blight disease, caused by Alternaria solani Sorauer, is a serious dis ease of potato foliage and tubers that occurs in most potato-growing region s world-wide. Developing new potato cultivars with resistance to early blig ht may reduce losses in the field and in storage, and lessen the need for f ungicide applications. A total of 280 clones, derived from 72 maternal half -sib families from a diploid random-mated hybrid population of Solanum phur eja x Solanum stenotomum were examined for resistance to early blight. The clones that were evaluated in a replicated field trial for 2 years in Penns ylvania, USA, had similar early blight intensity both years. Significant di fferences were found among families, within families and for the interactio n of years x within families. Broad-sense heritability for resistance, meas ured as area under the disease progress curve (AUDPC), was estimated as 0.7 3, with a 95% confidence interval of 0.65-0.78, and narrow-sense heritabili ty was estimated as 0.61 +/- 0.29 (P = 0.05). The correlation of AUDPC for early blight between years was 0.57 (P < 0.0001). These results suggest tha t this diploid population is worthy of use in breeding for early blight res istance.