Field, Microplot, and Greenhouse Evaluations of Resistance to Sclerotium rolfsii in Peanut

Abstract

Three of 12 virginia peanut (Arachis hypogaea) genotypes evaluated in the field for resistance to Sclerotium rolfsii had few disease loci and low ratios of dead plants to disease loci. Two of these genotypes (NC2 and NC Ac 18016) had upright canopies. NC 2 was tall and bushy and NC Ac 18016 was very compact. Another field-resistant genotype (NC Ac 18416) was tall but had a more spreading canopy than NC 2 or NC Ac 18016. NC Ac 18416 also showed partial resistance to infection in the greenhouse. A soil temperature of 28.degree. C and high humidity near the moist soil surface were highly conducive to disease development in the greenhouse. In field microplots, fewer sclerotia were recovered after NC 2 was grown than after NC Ac 18016 and NC Ac 18416 were grown. Differences in results in field, microplot, and greenhouse trials may have been caused by different resistance components in the genotypes evaluated.