Selection of early maturing barley with improved response to drought stress

Abstract

Selection for early maturing genotypes of barley with improved response to drought was practised among 303 F3 families derived from 11 crosses between five early and two late cultivars of highly diverse origins. Forty-one out of 152 uniformly early F3 lines were selected according to the mean performance and the regression stability index for number of ears/plant over a series of six drought-stressed and non-stressed environments established in clay and sandy soils. The performance of the 41 F4 selections and the five early parents was assessed under a short growing season of drought-stressed sandy soil treatments where plants were subjected to a 20-day dry period at different stages of plant age.Heritability for number of ears/plant estimated from parent-offspring regressions \vas higher under the favourable treatment of the clay soil (0.31) than under the stressed sandy soil treatments (0.15) A selection advance of 25.2% was manifested only under the favourable treatment of the clay soil. A correlated response to selection was also detected in grain yield/plant which amounted to 24.4% of the parental mean under the favourable treatment only. This was attributed to the strong association between number of ears/plant and grain yield/plant observed under the favourable condition which was rather weak under drought. Therefore, number of ears/plant in not a satisfactory selection criterion for developing betteryielding cultivars for moisture-stressed sandy soils. The expected genetic advance by selecting among F4 lines for grain yield/plant under drought is greater (28.7%) than that based on number of ears/plant (15.15%).The response of the early selections to drought stressed sandy soil treatments was characterized by a 10 days' reduction in time to flowering and a corresponding prolongation in time from flowering to maturity. Moreover, the early selections which recovered from a drought period imposed later than the seedling-jointing stage reached maturity earlier, but with significant increases in number of ears/plant and grain yield/plant than the control.