Breeding Sorghum with Resistance to Striga asiatica (L) Kuntze at ICRISAT Center

Abstract

Breeding for Striga resistance at ICRISAT Center, near Hyderabad, India, has the twin objectives of identifying sorghum source lines resistant to Striga asiatica and transfering the resistance to agronomically elite lines; 14 000 sorghum germplasm lines have been screened in the laboratory for their stimulant production and 640 low-stimulant lines have been identified. Studies on the genetics of stimulant production have indicated a preponderance of additive over nonadditive genetic variance. Selection for field resistance among the derivatives from Striga-resistant source lines x adapted crosses resulted in a higher proportion of field resistants in the low-stimulant than in the high-stimulant derivatives. In multilocation testing of the source lines, field reaction indicated that the best available low susceptible lines are N-13, 555, IS-4202, IS-7471, and IS-9985. The technique of growing test plants of the host in shallow seed pans in a soil medium has been found useful in differentiating resistant from susceptible host plants. An improved, three-stage system of screening for field resistance to Striga is described. Initial studies on Striga collected from five locations in India and four sorghum varieties indicated significant strain x variety interactions and SRN-4882B gave differential reaction. Intensive studies on host-parasite relationships, environmental interactions influencing Striga, screening methodology, guidelines to manage Striga sick fields, and surveys to understand species and race complexes have been projected as some of the priority areas of Striga research