Selection for early heading and salt-tolerance in bread wheat

Induced gene mutation has been used for the improvement of many crops, including wheat. Earliness is a valuable character agronomically, particularly in regions where temperatures rise during grain filling, and is readily induced. Gamma radiation was used to induce early maturity in a salt-tolerant late-maturing bread wheat genotype KTDH 19. Selection in early generations was for earliness, and in M-5 for high grain yield at 150 mol m(-3) NaCl. Assessments were made of leaf sodium content, K+/Na+ ratio at anthesis, and genetic parameters. Days to heading and yield had the highest heritabilities under both saline and nonsaline conditions. The M-5 generation showed significant positive correlations between yield and K+/Na+ ratio, and between days to heading and sodium content. There were significant negative correlations of days to heading with yield and K+/Na+ ratio, and between yield and sodium content. Of 62 early-heading M-5 genotypes, 10 had significantly lower leaf Na+ contents than the parents. Three which also had significantly higher grain yields were selected for multiplication and further study. These lines were approximately three weeks earlier in maturity: one had awns, unlike the parent, important for protection against bird damage. Results are discussed in terms of the potential of the material for salt-affected irrigated areas of Pakistan and India.