SCREENING OF WHEAT (Triticum aestivum L.) VARIETIES WITH HIGH NITROGEN USE EFFICIENCY UNDER RAINFED AND IRRIGATED CONDITIONS

The aim of this study was to clarify the relationship of nitrogen accumulation and transport with yield of wheat and determine the indicators for the screening of wheat varieties with high nitrogen use efficiency (NUE). A total of sixteen winter wheat (Triticum aestivum L.) varieties were used to determine fourteen nitrogen accumulation and transport-related traits as well as yield-related traits in field under irrigated and rainfed conditions. The correlations between the major nitrogen accumulation and transport-related traits and yield traits of wheat were analyzed, and the nitrogen use type of the wheat varieties was classified. Results showed that eight nitrogen accumulation and transport-related traits had significant or highly significant genetic correlations with yield per plant under the two water regimes. These eight traits were transport amount of pre- flowering reserve nitrogen and contribution of pre-flowering reserve nitrogen to grain nitrogen, nitrogen accumulation and transport amount after flowering, nitrogen transport efficiency after flowering, contribution of nitrogen assimilation to grain nitrogen after flowering, nitrogen utilization efficiency for grain production and biomass production. These eight traits were used as indicators for a comprehensive clustering of the wheat materials, and the sixteen varieties were classified into three groups representing the high NUE, intermediate, and low NUE types, respectively. From the perspective of nitrogen utilization, efforts must be made in the following aspects to obtain higher yields regardless of irrigated or rainfed conditions: 1) to improve nitrogen utilization efficiency for grain production and biomass production, as well as nitrogen accumulation and transport amount after flowering, nitrogen transport efficiency and contribution of nitrogen assimilation to grain nitrogen after flowering, and 2) to decrease transport amount of pre- flowering reserve nitrogen and contribution of pre-flowering reserve nitrogen to grain nitrogen.