This research conducted with an objective to study the morphological and biochemical parameters in sweet sorghum genotypes for shoot fly resistance. It was recorded that the genotype RSSV-260 (12.13) exhibited maximum mean value of trichome density and least percentage of dead heart (17) followed by genotype IS-18360 (21.86) and RSSV-167 (27.20). RSSV-260 and IS-18360 was as the good resistant as the genotypes SSV-84 and RSSV-269 for shootfly infestation, whereas the dead heart formation was greater on the genotypes SSV-84, RSSV-269 and RSSV-493. Total soluble protein and chlorophyll content were estimated higher in susceptible genotypes as compared to resistant. Susceptible genotypes showing maximum decreased rate of chlorophyll content as compared to resistant genotypes. The resistant genotypes viz., IS-18360, RSSV-260 and RSSV-167 recorded significantly lower soluble protein as compare to susceptible genotypes, SSV-84, RSSV-269 and RSSV-493. The average polyphenol oxidase activity was more in infected plant as compared to non-infected plant, means it was observed that activity of polyphenol oxidase increased after the infection of shootfly. It was observed that activity of peroxidase increased after the infection by shootfly which was higher in the resistant parents as compared to susceptible parents. Highest value for peroxidase and polyphenol oxidase activity recorded by the resistant parent IS-18360 and RSSV-260, it means parents showing the resistance mechanisms with higher activity of peroxidase and polyphenol oxidase enzyme.

Enzymatic activities suggested that the shootfly feeding leads to a loss in POX (Plant Oxidative Enzymes) activity in susceptible sweet sorghum genotypes. However, resistance genotypes may be able to tolerate shootfly feeding by increasing their POX activity. These biochemical characters can be used as marker traits in shootfly resistance breeding programme to broaden the genetic base and increase the level of resistance to sorghum shootfly.