Identification of resistance source of forage sorghum genotypes against the spotted stem borer (Chilo partellus)

Abstract

A field experiment was conducted during the kharif season of 2024-25 at ICAR-IIMR, Hyderabad, to evaluate forage sorghum genotypes for resistance to the spotted stem borer, Chilo partellus. Twenty genotypes, including resistant (IS 2205) and susceptible (Swarna) checks, were screened under artificial infestation for seven damage parameters. All traits showed highly significant differences (p<0.001). IS 2205 and Rampur Local consistently recorded the lowest damage, indicating strong antibiosis and/or antixenosis, whereas Swarna and DJ 6514 were the most susceptible. Principal component analysis revealed that PC1 and PC2 explained 72.23% of the total variation, with leaf damage, deadhearts, tunnelling, and exit holes identified as the most reliable resistance indicators. PCA-based grouping classified genotypes into resistant, moderately resistant, susceptible, and highly susceptible categories, providing valuable information for incorporating resistant sources into forage sorghum breeding programs aimed at durable stem borer management.