Genotypic Difference In Nitrogen Use Efficiency In Wheat

This study was carried out in Yangzhou,China in 2003 ~ 2004,in an attempt to understand the differences of nitrogen use efficiency in different wheat genotypes and to analyze their causes.which is necessary for the improvement of nitrogen use efficiency in wheat production.The different wheat genotypes were collected from jiangsu Province and were planted on 4 nitrogen levels, to study effect of N-application on grain yield and nitrogen use efficiency.The results were as following:1. Under the different N-application rate, there is significant variation in grain yield of different genotype wheat. CV is the biggest under 0 kgN/667m2. Increase application of nitrogen can decrease the variation.Under the 0 kgN/667m2, the average yield is 238.6 kg/667m2(range: 183.6-331.0 kg/667m2,CV: 13.03 ). Under the 9 kgN/667m2, the average yield is 410.9 kg/667m2(range: 329.3-484.8 kg/667m2,CV: 7.19 ). Under the 12 kgN/667m2, the average yield is 433.0 kg/667m2(range: 375.9 ~ 506.4 kg/667m2,CV: 7.02 ).Under the 15 kgN/667m2, the average yield is 436.9 kg/667m2(range: 382.3 ~ 502.6 kg/667m2,CV: 16.11).2. Under 9,12,15 kgN/667m2, CV of apparent recovery of applied N(AR) and nitrogen use efficiency for biomass production, nitrogen use efficiency for grain output are all big, which shows that there is significant variation in wheat nitrogen efficiency. Under 0,9,12,15 kgN/667m2,CV of nitrogen uptake efficiency for biomass production and nitrogen uptake efficiency for grain output are all big,too.The result of correlative analysis showed that correlation between apparentrecovery of applied N(AR) and nitrogen use efficiency for biomass production, nitrogen use efficiency for grain output is extremely remarkable. But it is not remarkable between nitrogen uptake efficiency for biomass production and nitrogen uptake efficiency for grain output. With the increase of N-application, the correlation coefficient all descend gradually.3. Clustering analyzing the wheat with the index of grain yield, the result showed that wheat genotypes can be classified correspondingly 3 types under 4 N-application rate. With the index of apparent recovery of applied N(AR), and nitrogen use efficiency for biomass production, and nitrogen use efficiency for grain output, and nitrogen uptake efficiency for biomass production, and nitrogen uptake efficiency for grain output, the clustering analysis showed that there are 3 types of nitrogen efficiency: efficient type, mid-efficiency type, inefficient type. Synthesize the result of clustering analysis, we can find out some wheat genotypes, which have characters of high yield, high nitrogen efficiency in different N-application, such as yangmai 5, yangmai 12, xu 856-under 9kgN/667m2,yang 12 ,hong 3, xixi 22-under 12 kgN/667m2 ,yangmai 5,xu 974-under 15kgN/667m2, and so on.