Screening genotypes for improving wheat yield in alkaline dispersive subsoils in a medium rainfall region of south eastern Australia

Alkaline dispersive subsoils are common in cropping areas of south-eastern Australia, which exhibit a range of physiochemical properties including dispersion, poor structure, impeded drainage, waterlogging and high soil strength. These properties restrict the rooting depth of crops, resulting in yield penalties due to reduced extraction of water and nutrient. In a multiyear field screening trial, we combined the use of high-resolution, low-altitude aerial imaging for rapid phenotyping of crops with physiological and agronomic measurements to identify the traits contributing tolerance to alkaline dispersive subsoil. The intense drought conditions experienced in the study years revealed considerable genotypic variation with some genotypes having more than a 3-fold higher grain yield than others. Observed grain yield was correlated with harvest index but not biomass indicating the ability of high yielding genotypes to alleviate the drought stress by accessing subsoil water. Observed traits associated with this greater yield performance should prove to be crucial in future breeding programs.