Evaluation of Detached Leaf Culture for Screening Peanuts for Leafspot Resistance1

Abstract

A detached leaf culturing technique has been proposed as a rapid and simple method for screening peanut (Arachis hypogaea L.) genotypes for leafspot resistance. This study was conducted to (a) determine the effect of both leaf age and outdoor plant weathering on infection with Cercospora arachidicola Hori as measured by the detached leaf technique, (b) evaluate the resistance to early leafspot of several peanut genotypes in the field and in the greenhouse using the detached leaf technique, and (c) determine the relationship between leafspot resistance measured in the field and the greenhouse.The age of the leaf had a significant effect on leafspot resistance when evaluated using the detached leaf technique. Younger leaves averaged 11.4 lesions per leaflet compared to 5.6 lesions per leaflet for older leaves. The number of lesions per leaflet was similar for weathered and greenhouse-grown plants. PI 270806, PI 109839, Kanyoma, and PI 259679, four Virginia (ssp. hypogaea var. hypogaea) types, were the most resistant genotypes evaluated in these tests.The number of lesions per leaflet caused by early leaf-spot for the 16 genotypes measured by the detached leaf technique was significantly correlated (r = 0.85) with the same trait measured in the field. PI 109839 had the fewest number of lesions per leaflet in both greenhouse and field tests.