Selecting traits to improve the yield and water use efficiency of winter wheat under limited water supply

Abstract Using high-yielding cultivars is an important measure to maintain grain production, especially in dryland environments. A field study in the 2016/17 and 2017/18 seasons was conducted at Luancheng station in the North China Plain (NCP) to investigate winter wheat cultivars with high-yielding characteristics under water deficit conditions. The experiment contained two parts, with part one involving 10 cultivars of winter wheat grown under I0 (rainfed), I1 (one irrigation) and I2 (two irrigations) treatments and part two involving 32 cultivars grown under I1 treatment. The three irrigation regimes I0, I1, and I2 provided approximately 60 %, 70 % and 80 % of the seasonal potential evapotranspiration, respectively. Yield variations were up to 47 % among the 10 cultivars in the two seasons, and several cultivars could produce continuously higher yields than those of other cultivars under the different treatments. High-yielding cultivars produced higher water productivity than that of other cultivars. No single agronomic or physiological characteristics, except for biomass, could explain the yield differences among cultivars. However, canopy temperature (CT) during the grain filling stage had a continuous negative linear correlation with grain yield under limited water supply conditions in a high-yielding environment. The results indicated that the genetic variation in grain yield might be attributed to the ability to withdraw soil water, especially the deeper soil water, during the grain filling stage, which would result in a cooler canopy. CT as an indicator of high-yielding cultivars was further confirmed among the 32 cultivars under I1 treatment in the 2016/17. A relative adequate water supply during the grain filling stage also prolonged leaf greenness which was beneficial to dry matter production and grain yield. Therefore, the ability to efficiently utilize soil water and maintain dry matter production during the grain filling stage are two important characteristics for maintaining the high yield of winter wheat under water deficit conditions in the NCP.