Breeding sorghum for shoot fly resistance

Abstract

Shoot fly, Atherigona soccata (Ronadani) is the most important insect pest on sorghum, which severely damages the crop during the seedling stage. Larvae crawl into the central whorl, cut the terminal growing bud, and feed on the decaying tissue which results in the drying of central leaf, typically causing deadheart (DH). Host plant resistance is one of the major components to control sorghum shoot fly. Entries with faster seedling growth rate, narrower leaves, greater trichome density, glossy leaf surface are important for resistance to sorghum shoot fly. To breed lines incorporated with these traits for resistance, we followed single seed decent method in developing F8 material of two crosses between highly susceptible seed parent, 296B and two resistant germplasm lines, IS 18551 and IS 2205. The genetic material was evaluated over two rainy seasons of 2016 and 2017 following standard fish-meal technique. Results indicated that eight of the progenies were significantly better than the seed parent, 296B and were on par with the resistance sources for their shoot fly reaction. The resistant progenies exhibited all the desirable traits of resistance. The shoot fly damage (measured as % DH) was significantly low (-47%) in the progenies than the seed parent, 296B. Similarly, as compared to susceptible parent, these progenies were quick in their seedling growth (61% higher seedling height), had significantly lesser number of eggs per seedling (-52%), epicuticular wax load (-54%), higher leaf glossiness (54%), higher abaxial (135%) and adaxial (457%) trichome density. In addition, these lines are agronomically good for grain yield, and hence can be of much use in sorghum breeding to improve shoot fly resistance.