Impact of Stem Rot (Sclerotium rolfsii) Pressure on Genetic Variability, Heritability, and Genetic Advance for Yield Traits in Groundnut (Arachis hypogaea L.)

Stem rot caused by Sclerotium rolfsii is a major constraint to groundnut (Arachis hypogaea L.) production. The present investigation assessed genetic variability, broad-sense heritability and genetic advance for 16 traits in 29 genotypes comprising nine parents and 20 F₁ hybrids evaluated under normal and stem rot sick-plot conditions during the rabi 2024–25 season at Tirupati, Andhra Pradesh, using a randomised block design with two replications. Phenotypic and genotypic coefficients of variation (PCV and GCV) varied across traits and environments. Genotypic differences were significant for all traits except stem rot incidence under normal conditions and shelling percentage under sick plot conditions. PCV and GCV ranged from 2.61–94.44% and 2.59–90.86%, respectively, under normal conditions, compared with 2.73–76.48% and 2.70–73.96% under sick plot conditions. Broad-sense heritability ranged from 13.97–98.98% under normal conditions and 16.38–98.34% under sick plot conditions, while genetic advance as a percentage of the mean (GAM) ranged from 5.31–180.05% and 2.54–147.32%, respectively. Pod yield plant-1 showed high heritability and GAM in both environments, with estimates increasing from 92.98% and 35.80% under normal conditions to 98.34% and 67.38% under disease stress. Heritability for stem rot incidence increased from 13.97% to 88.54%, accompanied by an increase in GAM from 25.75% to 97.35%. Plant height, primary branches plant-1, secondary branches plant-1, number of mature pods plant-1, 100-pod weight, dry haulm weight plant-1, kernel yield plant-1 and pod yield plant-1 combined high heritability with high GAM in both environments. These traits offer promising selection criteria, while sick-plot evaluation provides a stronger basis for distinguishing genotypes for stem rot response.