Morphological and Biochemical resistance in sorghum genotypes against Sorghum shoot fly, Atherigona soccata (Rondani) (Muscidae: Diptera)

Sorghum shoot fly, Atherigona soccata (Rondani) is an important pest of sorghum distributed in almost all sorghum growing areas of India, attacking the crop at the seedling stage wherein the absence of appropriate management measures may result in heavy yield loss and host plant resistance is a major component in managing this pest. Utilization of resistance as a control strategy has very much practical relevance and hence identification of resistant sources for shootfly through morphological and physicochemical characteristics was carried out in pre-release sorghum genotypes of Tamil Nadu Agricultural University. Leaf glossiness, trichome density, trichome length, trichome width, and seedling vigor were associated with resistance and had a major bearing on the expression of resistance to shoot fly. Among the genotypes tested, TNS 671 and TNS 665 showed better performance in terms of dead heart, percentage of plants with eggs, and recovery resistance compared to others which were then subjected to biochemical estimation and GCMS analysis. Leaf biochemical characters viz., total phenol, cellulose, total amino acids, silica, tannin, and lignin were found to be negatively correlated and total sugar positively correlated with resistance. GC-MSanalysis of the sorghum genotypes revealedthe presence of compounds, viz., carboxylic acids, heptadecene, and hentriacontane only in the resistant entry, IS18551. An interesting finding of this study was the presence of hentriacontanein resistant cultivar, IS18551 which is reported to have kairomonal activity. The characters associated with resistance or susceptibility can be used in further resistant breeding programmes.