Field Reaction to Indian Stem Rust Races of Wheat Lines and Varieties Having Known Genes for Resistance

Studies were conducted to test the field reaction to Indian races of stem rust of different Sr lines and other varieties known to carry specific genes for resistance to this rust. With few exceptions most of the Sr genes were ineffective individually against Indian races of stem rust in the field. Sr 9b gave certain measure of resistance under north Indian conditions as represented by Delhi, but it succumbed at Wellington, South India. It appeared that Sr 9a and Sr 9b could be used to distinguish certain Indian races of stem rust. Sr 11 which was extensively used in the earlier breeding work in India has become susceptible in the field. Certain wheat varieties like C.U. III-23-2419, Veadeiro, N.P. 790, Kenya 318.03. B.2, Kenya Farmer, Timgalin and TD 1656 appear to be very promising for field resistance to stem rust in India. The fact that certain lines or varieties which were resistant at one location are susceptible at another distant location indicates that these lines or varieties can be conveniently used for screening of races.