Evaluation of barley mutants for drought tolerance: a physiology — breeding approach

Induced mutants are useful not only for cultivar development but also as research tools for basic studies. A barley mutant collection maintained at Akdeniz University was evaluated for development of cultivar and breeding populations for semi-dry conditions. Results in dry environments have indicated that both drought escape and drought tolerance can contribute to better grain yields under drought stress at heading and grain filling periods. Two types of mutants were investigated; those affecting traits involved in stress tolerance and those facilitating breeding procedures. Early-heading induced mutants, which escaped the drought period, had a greater grain yield because of a longer grain-filling period. Genetic male-sterile mutants were successfully used to overcome hand emasculation. Outcrossing frequency was determined on collected spikes from induced male sterile mutants and fluctuated greatly with environments and populations. However, it was sufficient for developing recurrent selection strategies. Using mutants as cross parents generated transgressive variability in yield components. The mutant collection was screened for characters tolerating abiotic stresses as well as its suitability for physiological and biochemical basic studies. An ABA insensitive induced mutant, Akdeniz-M-Q-54, was discovered. Photosynthetic rates for several mutants, including M-K-1, M-K-5, M-K-18 were consistently higher than the parent variety ‘Kaya’, both in field and greenhouse studies. Similarly, improvements were obtained for transpiration rate and stomatal conductance. Two glaucous mutants, M-K-49 (sdw) and M-K-55 had lower leaf Na+ and Cl- concentrations than Kaya when the leaves were sprayed with salt. M-K49 had significantly higher leaf surface wax contents than Kaya at the vegetative stage.