Identification of Sweet Sorghum Accessions Possessing Multiple Resistance to Shoot Fly (Atherigona soccata Rondani) and Spotted Stem Borer (Chilo partellus Swinhoe)

Thirty-two sweet sorghum genotypes were evaluated for resistance to shoot fly and stem borer during rainy seasons 2009–2012. The parameters viz., seedling vigour, glossiness, dead-hearts caused by shoot fly, stem borer, stem borer leaf damage score, stem borer stalk tunneling, stem borer exit holes and stem borer larvae/stalk were assessed for their contribution in imparting resistance to A. soccata and C. partellus. None of the traits considered could discriminate entries as resistant/ susceptible individually. In view of the complexity of interactions between A. soccata, C. partellus with sorghum, principal component analysis was applied considering seven parameters viz., seedling vigour, seedling glossiness, dead-hearts caused by shoot fly, stem borer, stem borer stalk tunneling, stem borer exit holes/stalk and larvae recovered/stalk. Two principal components were extracted explaining a cumulative variation of 84.6 %. PC1 and PC2 explained 69.5 and 15.1 % of the variations, respectively indicating that seedling vigour, glossiness, dead-hearts caused by both pests, stem borer exit holes/stalk were the most reliable parameters for characterization of multiple resistances to A. soccata and C. partellus. The sweet sorghum lines IS 5353, IS 18164, ICSV 93046, ICSV 700, GGUB 50 were classified as resistant to both the pests. The multiple resistant lines with durable resistance can be employed in future sweet sorghum breeding programs for enhancing levels of resistance to shoot fly and stem borer.