Leafspot Disease Progression and Components of Resistance Among Selected Peanut Genotypes in Ghana

Abstract

ABSTRACT Early and late leafspot diseases are major constraints in peanut production, causing up to 70% yield losses in combined occurrences. Phenotyping has focused mainly on disease incidence and severity with little attention on disease progression and component traits that determine overall resistance. This study distinguished resistant and susceptible genotypes based on disease progression and components of resistance. Ten peanut genotypes were evaluated under natural leafspot pressure at Nyankpala, Ghana, over two cropping seasons. The set included six genotypes derived from crosses between BC 3 F 6 interspecific introgression lines and Spanish peanut genotypes and four released varieties. Disease incidence, severity, lesion number and diameter, and percentage of necrotic area were recorded to compute area under disease progress curve (AUDPC) and residence indices. Results revealed that leafspot disease progressed steadily among susceptible peanut genotypes as compared with the resistant genotypes. Susceptible genotypes exhibited higher lesion number, lesion diameter, and percentage necrotic area, which showed strong positive correlations with AUDPC‐ELS, AUDPC‐LLS, and AUDPC‐DI. L076J had the highest resistance based on components of resistance index, whereas Nkatiesari had the highest level of resistance based on the disease progression index (DPI). Integrating both components into an overall resistance index (ORI) classified Nkatiesari and Sarinut‐1 as resistant; L076J, L027B, and L010A1 as moderately resistant; L030, L046, and L104B as susceptible; and Sarinut‐2 and Chinese as highly susceptible. These resistant genotypes provide valuable sources for leafspot management and peanut improvement in sub‐Saharan Africa.