The Physiological Basis of Drought Tolerance Identified from Genetic Association Analysis.

Drought limits wheat yield and the identification of physiological traits linked to chromosomal regions conferring yield under water stress could enhance the process of wheat improvement. Twenty (20) wheat lines carrying complementary genomic regions based on association analysis of multi-environment trials for yield and two cultivar mixtures, also combining complementary regions, were evaluated under irrigated and drought conditions in full tillage and no tillage regimes to identify traits linked to yield.  Number of days to heading(DH), thousand kernel weight(TKW), biomass, normalized difference vegetation index(NDVI) and plant height accounted for 81.2%  of the observed genetic variation in yield. No significant(p<0.05) genotype x tillage interaction effects  under both irrigated and drought regimes were observed. Results revealed that higher wheat yields could be obtained under no-tillage drought conditions when Merinda, Crusader, Janz, Spitfire and Sunstate varieties are cultivated. Lincoln, Suntop, Lincoln + Lang tended to perform better under irrigated conditions. These preliminary results suggest that mixtures have the potential to increase yield as well as buffer drought effects. The physiological traits identified could be targeted to improve wheat yield under drought stress in northwestern NSW