Physiological and Morphological Basis of Improved Water‐Use‐Efficiency in Wheat from Partial Root‐Zone Drying

Abstract

ABSTRACTWater‐saving breeding and cultivation of winter wheat (Triticum aestivum L.) have always been among the important missions in North China. But there is still a dispute on the regulation of water use in winter wheat. A pot experiment was conducted to investigate the physiological and morphological mechanisms of water use in two cultivars of winter wheat (KN9204 and drought‐tolerant LH2) via partial root‐zone drying (PRD). The results indicated that the weight of 1000 grains was higher under PRD conditions for both cultivars. Total water consumption per plant significantly decreased by 11.6 and 17.3% for KN9204 and LH2, respectively, and water‐use efficiency (WUE) significantly increased by 17.2 and 20.3% under PRD. The net photosynthetic rate did not differ between PRD and full irrigation (FI) for either cultivar; however, transpiration rate was lower under PRD than FI, which improved WUE at the leaf level. Flag leaf water potential was significantly lower under PRD than FI for both cultivars, while water content was similar for both treatments. The soluble sugars content of leaves of KN9204 was higher under PRD than FI, while the proline content was 45.9% (KN9204) and 15% (LH2) higher under PRD. Stomatal density increased under PRD, but stomatal width and area declined. Overall, the two types of winter wheat had both common and individual means of improving WUE under PRD conditions. The results would further improve the theoretical underpinning of water‐saving breeding and cultivation in winter wheat.