施氮量对不同品种苜蓿结瘤固氮和产量及粗蛋白含量的调控

Regulation of nitrogen application rate on nodulation,nitrogen fixation,yield,and crude protein content of different alfalfa varieties

摸清不同苜蓿品种结瘤固氮对氮肥用量的响应,增强苜蓿固氮能力与产量和品质的协同,对于苜蓿节氮增效的生产实践至关重要。采用10个苜蓿品种并设置5个氮梯度,通过测定地上部生物量及粗蛋白含量和根瘤数、根瘤重、固氮率及固氮量,探究施氮对不同品种苜蓿建植当年的生物量、粗蛋白含量和结瘤固氮的影响及相互调控关系。结果表明,地上部生物量和粗蛋白含量在不同品种和处理间差异显著,两项指标均较高的品种超新星、佰苜202、骑士T、佰苜341和绿思乐的固氮效率显著高于其他品种。固氮率对施氮量响应在茬次间差异显著,第一茬N0处理下最高,第二茬或仅收获1茬时N25、N50处理下最高,粗蛋白含量与之呈正相关变化。在N0~N50处理下,高固氮率品种的生物量和粗蛋白含量比低固氮率品种分别高1.2%~16.7%和12.9%~19.2%,N100、N150处理与其相比,除固氮率较低的第一茬外,生物量差值基本相等,粗蛋白含量差值显著降低至7.8%~12.3%,低固氮率品种粗蛋白积累对施氮依赖更高。生物量和粗蛋白含量与结瘤固氮指标呈显著正相关。建植当年,适量施氮有利于苜蓿固氮协调增效,超新星等固氮效率较高的5个品种在较低氮梯度下生物量和粗蛋白含量可平衡提升,且显著高于其他品种,可作为节氮栽培的优良品种。

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.