Effective Selection Criteria for Screening Drought Tolerant and High Yielding Bread Wheat Genotypes
Bread wheat is the major staple food in Morocco. Drought is the most important abiotic stress decreasing yield. Breeding for drought tolerance may be improved by various plant traits. In order to investigate the best selection criteria to develop drought tolerant varieties, 40 bread wheat genotypes were evaluated under two locations representing the stressed and non-stressed environments, using randomized complete block design with three replications during the cropping season 2014. Under stressed conditions, analysis of variance exhibited significant differences among grain yield, thousand kernel weight, number of plants, number of spikes and tillers per plant, plant height, plant vigor, chlorophyll content and canopy temperature; and non-significant differences for biomass, harvest index, number of days to heading and flowering, and chlorophyll fluorescence. According to correlation and principal component analysis, the grain yield was positively related with biomass, thousand grain weight, number of fertile spikes and plant vigor; and indirectly associated positively with harvest index, plant height and negatively with number of days to flowering, canopy temperature and chlorophyll content. Those traits, correlated to grain yield under stress, can be used as indirect selection for drought tolerance to obtain higher yield potential in dryland conditions. Moreover, thousand grain weight in non-stressed conditions was positively correlated to biomass, number of fertile spikes and its homologue in stressed conditions. Also, the biomass in favorable conditions was correlated to thousand grain weight and harvest index in mild stressed conditions. Thus, those two traits may be used to improve performance in drought prone environments.