Deeper root distribution and optimized root anatomy help improve dryland wheat yield and water use efficiency under low water conditions

Background and aimDeep roots are important for crops to access water when the topsoil is dry. Root anatomy and activity play an important role in water uptake. However, little is known about the effects of root distribution and anatomical structure on water uptake and grain yield under different water conditions. This study aimed to reveal the contribution of deeper roots, root anatomy and root activity on grain yield and water use efficiency.MethodsA field experiment and Rhizobox experiment were performed to evaluate the effects of changes in root distribution, root anatomy and root activity on grain yield and water use efficiency under three water conditions. Three dryland wheat cultivars (BM1, CH58 and CH1) were compared.ResultsBM1 formed a root system, which limited the acquisition of water in the subsoil, resulting in lower grain yield and water use efficiency in field and rhizobox experiments. In contrast, cultivars CH58 and CH1 exhibited greater root biomass and root length density in the subsoil, optimizing subsoil water uptake, thereby increasing grain yield and water use efficiency. CH58 had a smaller root diameter and vessel diameter, thicker cortex thickness, higher root cortex thickness-to-diameter ratio and higher root activity.ConclusionThis study demonstrated that, deeper roots, root anatomy and root activity are important traits in selecting wheat cultivars that maintain yield under low water conditions. Therefore, wheat crop development and breeding to improve grain yield should also consider optimizing root anatomy and improving root activity while promoting deep root development.