Inheritance of Early Leaf Spot Resistance in Different Generations of Groundnut (Arachis hypogaea L.) under Natural Epiphytotic Conditions

Abstract

Early leaf spot (ELS), caused by Cercospora arachidicola Hori, is a major foliar disease of groundnut that can cause considerable yield loss under favourable conditions. Understanding the inheritance of resistance is fundamental to developing resistant cultivars through conventional and molecular breeding approaches. The present investigation was undertaken to elucidate the inheritance pattern of early leaf spot resistance using six generations (P1, P2, F1, F2, BC1 and BC2) derived from contrasting resistant and susceptible parents at the Research Farm, Department of Genetics and Plant Breeding, RVSKVV, Gwalior, in a randomised block design (RBD) with three replications. Data were recorded from 20 plants per replication, i.e., 60 plants in total. Disease severity was assessed under natural epiphytotic conditions using the standard 1–9 disease rating scale at 30, 45 and 60 days after sowing. TG-86 and Nitya Harita maintained low disease scores throughout the assessment, whereas DH-245 and DH-257 showed a marked increase in disease severity and were susceptible at 60 DAS. Among the crosses, TG-86 × DH-245, TG-86 × DH-257 and Nitya Harita × DH-257 showed better resistance, with their F1 generations reflecting resistance. Their F2 generations also recorded low disease reactions, indicating the presence of resistant segregants. Nitya Harita × DH-245 showed a moderately resistant F1 response, while its F2 and BC1 generations recorded highly resistant reactions to ELS. TG-86 and Nitya Harita were identified as useful resistance sources, while promising crosses such as F2 by selfing (TG-86 × DH-257), BC1- (Nitya Harita × DH-245) × Nitya Harita and F2 by selfing (Nitya Harita × DH-245) may be utilised further in breeding programmes for the genetic improvement of groundnut for ELS resistance.