Screening and cluster analysis of nitrogen use efficiency of different wheat cultivars at the seedling stage

【Objectives】Excessive application of nitrogen fertilizer lead tonitrogen loss and cost increase of agricultural production. Screening and breeding crop cultivars with high nitrogen use efficiency is effective way of increasing nitrogen fertilizer use efficiency and reducing environmental risks. In this paper,44 wheat cultivars at the seedling stage for theirpotential of high nitrogen use efficiency were screened.【Methods】Hydroponic experiments were conducted with normal (5 mmol/L) and high (45 mmol/L) nitrogen levels. Evaluation indices were standardized by the method of Subordinate function into interval 0,1, and the standardized data were calculated into a dimensionless integrated values by objective weighting method. Based on the comprehensive value using the shortest distance method and squared euclidean distance method of clustering analysis, 44 wheat cultivars were divided into different categories using their nitrogen use efficiency. 【Results】There are significant differencesin shoot dry weight (SDW), root dry weight (RDW), leaf area (LA), shoot nitrogen accumulation (SNA) and root nitrogen accumulation (RNA) of the wheat cultivars between the two N supply levels. The coefficients of variation (CV) of SDW, RDW, LA, SNA and RNA are between 27.9%-33.7% and 21.5%-33.7% under the normal and high nitrogen levels, respectively. The integrated nitrogen use efficiency values (INUEV) under the normal and high nitrogen levels at the seedling stage are 0.053-0.920 and 0.001-0.853, respectively. The INUEV of Jian76 wheat cultivar is greater than 80% under the both normal and high nitrogen levels. Based on the INUEV and the clustering analysis (CA) of INUEV, the 44 wheat cultivars are divided into three categories which are high, middle and low nitrogen use efficiencies (NUE). The Yangmai16 and Jian76 belong to high NUE category under both normal and high nitrogen levels, and the Wanmai68, F60501-4, Jian62 and Annong1026 belong to high NUE wheat cultivars only under the high nitrogen level. The wheat cultivars with high, middle and low nitrogen use efficiencies in the normal nitrogen condition account for 4.54%,54.55% and 40.91%, and 13.63%, 38.64 and 47.73% high nitrogen condition. 【Conclusions】 The shoot nitrogen accumulation, shoot dry weight, root nitrogen accumulation, root dry weight and leaf area can be used as indices to evaluate the potentials of wheat cultivars at the seedling stage; The Yangmai16 and Jian76 are preliminary confirmed as the wheat cultivars with high nitrogen use efficiency in the normal and high nitrogen conditions, Wanmai68, F60501-4, Jian62 and Annong1026 as cultivars with high nitrogen use efficiency in the high nitrogen conditions.