A synergistic increase in water and nitrogen use efficiencies in winter wheat cultivars released between the 1940s and the 2010s for cultivation in the drylands of the shaanxi Province in China

摘要

Although soil water and nutrients are two of the most important factors affecting growth and production of winter wheat, genetic improvement for wheat responses to water and nitrogen (N) levels has been rarely studied. In this paper, five dryland winter wheat cultivars representative of widely cultivated varieties released from the 1940s to the 2010s in Shaanxi Province, China, were grown in an open rainout shelter (which could be closed when rain threatened) under four contrasting water/N treatment combinations. Yield-related parameters, biomass accumulation, crop water productivity (WUE), and nitrogen use efficiency (NUE) were determined. The results indicated that water deficit and low N treatment caused a significant reduction in grain yield and flag leaf photosynthesis in the five wheat cultivars studied. However, NUE, grain protein content, and partial factor nitrogen productivity were significantly improved by N application under water deficit. Our results confirm the genetic improvement for plant growth, N accumulation, and grain yield in wheat cultivars released from the 1940s to the 2010s; newergenotypes showed the highest NUE under water deficit combined with N limited conditions. Additionally, based on principal component analysis, we found that the newer genotypes, i.e. those from the 2000s and the 2010s, are more sensitive to low nitrogen and water stress compared with the older genotypes from the 1980s, which are more sensitive to the combined effect of water and N limitations. Our findings provide a theoretical support for further improvement of the wheat yield potential, selection, and breeding of high-efficiency varieties in arid and semi-arid areas.