Components of Resistance to Late Leafspot in Peanut. II. Correlations Among Components and Their Significance in Breeding for Resistance1

Abstract

Abstract A total of 116 peanut (Arachis hypogaea L.) genotypes, which included all market types, were evaluated for resistance to late leafspot (Cercosporidium personatum Berk, and Curt. (Deighton)) in three tests during 1986. Two tests were conducted in greenhouses at Gainesville and Quincy, Florida. The third test was conducted in the field near Marianna, Florida. Lesion number per leaf, percent leaf necrotic area, lesion diameter, spore production, and latent period were evaluated. Correlations were calculated between greenhouse and field studies. Contributions of each component of resistance to an overall plant appearance score was also determined. Amount of sporulation, lesion size, and latent period were highly correlated with each other and with percent leaf necrotic area within tests. The rank of genotypes in the field was significantly correlated with the rank in the greenhouse for latent period (r = 0.57), lesion diameter (r = 0.46), and sporulation (r = 0.59). Sporulation, lesion size, and latent period were the most important components contributing to visual plant appearance score. Sporulation accounted for most of the variability in the score.