Division of Genetics, Indian Agricultural Research Institute, New Delhi-110 012
The inheritance of resistance to aphid in barley was studied in 19 crosses involving six resistant and 14 susceptible strains. All the six strains had derived resistance from ‘EB 921’. The F1’s showed dominance for susceptibility. The segregation ratios in the F2’s, back-crosses and three way crosses suggested that aphid resistance of ‘DL 59’, ‘DL 79’, ‘DL 117’, ‘DL 144’, ‘DL 181’ and ‘DL 200’ was conditioned by two recessive complementary gene pairs. Modifying factors also operated to control the intensity of infestation on the susceptible plants. Among the susceptible parents, ‘K 125’ carried one dominant gene pair and the remaining had two dominant factors. The genes conditioning resistance of ‘DL 150’ (Bl) were allelic to those present in ‘EB 921’.
