LEAFSPOT DISEASE EPIDEMICS AND COMPONENTS OF RESISTANCE OF SELECTED GROUNDNUT (Arachis hypogaea L.) GENOTYPES IN GHANA

Abstract

Leafspot disease is a major yield limiting factor in groundnut growing areas in Northern Ghana. This study was to monitor the progression of the disease in ten selected groundnut genotypes. Six were derived from a cross between BC3F6 interspecific introgression lines (43-09-03-02 or 60-02-03-02) and Spanish groundnut genotypes (Schubert and TS32-1) while the remaining four are released groundnut varieties in Ghana. Nkatiesari and Chinese served as the resistant and susceptible checks, respectively. The experiment was conducted on an experimental field of CSIR- Savanna Agricultural Research Institute in Ghana during the 2020 and 2021 cropping seasons under natural field infections. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. Disease incidence and progress, as well as severity were monitored for both 2020 and 2021 cropping seasons. Leafspot epidemics measured as AUDPC for disease incidence and severity were more severe for L0104B, Chinese and Sarinut-2. AUDPC values for resistant check (Nkatiesari) were comparable to Sarinut-1, L027, L076J and L010A1. Initial inocula and infection rates, lesion number, lesion diameter, and percentage necrotic areas, were higher for the susceptible genotypes. Based on disease rating and yield data, Chinese, Sarinut-2, L046 were classified as leafspot tolerant genotypes while Nkatiesari, Sarinut-1, L027B and L076J considered resistant genotypes. A molecular study to determine the genes responsible for resistance in the resistant genotypes should be considered in future studies