Regulation of nitrogen application rate on nodulation,nitrogen fixation,yield,and crude protein content of dif-ferent alfalfa varieties
Understanding the response of different alfalfa varieties to nitrogen fertilizer application for nodulation and nitrogen fixation,and enhancing the synergy between alfalfa nitrogen fixation ability and yield and quality,are crucial for the production practice of alfalfa nitrogen conservation and efficiency enhancement.In this study,ten alfalfa varieties were used and five nitrogen gradients were set up.By measuring the aboveground biomass,crude protein content,root nodule number,root nodule weight,nitrogen rate and amount fixed from the atmosphere,the effects of nitrogen application on the biomass,crude protein content,and nodule nitrogen fixation of different alfalfa varieties in the year of establishment and their mutual regulatory relationship were explored.The results indicated that there were significant differences in aboveground biomass and crude protein content among different varieties and treatments.The nitrogen fixation efficiency of varieties with higher aboveground biomass and crude protein content,such as Chaoxinxing,Baimu 202,Qishi T,Baimu 341 and Lvsile,was significantly higher than that of other varieties.The response of nitrogen derived from the atmosphere to nitrogen application rate showed significant differences between two alfalfa cuts.The first cut had the highest response under the N0 treatment,and the second cut or only one cropping had the highest response under N25 and N50 treatments.The crude protein content showed a positive correlation with it.Under N0-N50 treatments,the biomass and crude protein content of high nitrogen fixation efficiency varieties were 1.2%-16.7%and 12.9%-19.2%higher than those of low nitrogen fixation efficiency varieties,respectively.Compared with N100 and N150 treatments,except for the first cut with lower nitrogen derived from the atmosphere,the biomass difference was basically the same,and the crude protein content difference was significantly reduced to 7.8%-12.3%.The crude protein accumulation of low nitrogen fixation efficiency varieties was more dependent on nitrogen application.There was a significant positive correlation between biomass and crude protein content and nodulation nitrogen fixation indicators.In the year of planting,appropriate nitrogen application was beneficial for the coordinated and efficient nitrogen fixation of alfalfa.Five varieties with higher nitrogen fixation efficiency,such as Chaoxinxing,could achieve a balanced increase in biomass and crude protein content under lower nitrogen gradients,and were significantly higher than other varieties.They could be used as excellent varieties for nitrogen-saving cultivation.
alfalfa varietiesnitrogen application ratebiomasscrude protein contentnodulation and nitrogen fixation15N natural abundance
NETL
NSTL
万方数据
