不同施氮量对苜蓿干物质累积和氮素吸收的影响

Effects of different nitrogen application rates on dry matter accumulation and nitrogen uptake of alfalfa

旨在探究不同施氮量对科尔沁沙地紫花苜蓿生物量累积和氮素吸收规律的影响。本试验以建植当年紫花苜蓿为供试材料,设置4个施氮梯度,施氮量分别为0 kg/hm^(2)(N0)、22.5 kg/hm^(2)(N1)、45 kg/hm^(2)(N2)和67.5 kg/hm^(2)(N3),测定紫花苜蓿株高、地上生物量以及全氮含量,并进行综合分析。结果表明:1.苜蓿初花期到盛花期,与N0相比,施用氮肥(N1除外)显著提高苜蓿株高幅度为11.55%~13.73%(P<0.05)。2.苜蓿孕蕾期,与N0相比,施氮处理(N2)显著提高苜蓿生物量61.32%(P<0.05)。3.与N0相比,施用氮肥显著提高苜蓿氮素含量和氮素吸收量;苜蓿各生育时期地上生物量累积量和累积速率呈增加趋势;在苜蓿生育前期,苜蓿氮素吸收累积量和吸收速率呈增加趋势(N3最高),生育后期则呈降低趋势(N2最高);不同施氮处理对苜蓿氮素利用效率的影响差异不显著(P>0.05)。4.在苜蓿整个生育时期,与N2和N3相比,低氮处理(N1)显著提高偏生产力。综合以上,在科尔沁沙地,45 kg/hm^(2)是苜蓿生产中的最佳施氮量。该研究可为苜蓿生产力提升及氮素营养高效利用提供参考。

To investigate the effects of different nitrogen application rates on biomass accumulation and nitrogen uptake of alfalfa in Horqin Sandy land,the alfalfa in the establishment year was used as the test material,and four nitrogen application gradients were set up,with nitrogen application rates of 0 kg/hm^(2)(N0),22.5 kg/hm^(2)(N1),45 kg/hm^(2)(N2)and 67.5 kg/hm^(2)(N3),respectively.The plant height,above-ground biomass and total nitrogen content of alfalfa were determined.And make a comprehensive analysis.The results showed as follows:1.Compared with N0,the plant height of alfalfa was significantly increased by 11.55%~13.73%(P<0.05).2.Compared with N0,nitrogen treatment(N2)significantly increased the biomass of alfalfa by 61.32%(P<0.05).3.Compared with N0,application of nitrogen fertilizer significantly increased nitrogen content and nitrogen uptake of alfalfa;the aboveground biomass accumulation and accumulation rate of alfalfa in different growth stages showed an increasing trend.In the early growth stage of alfalfa,nitrogen uptake accumulation and uptake rate increased(N3 was the highest),but decreased(N2 was the highest)in the later growth stage.The effects of different nitrogen application treatments on nitrogen use efficiency of alfalfa were not significant((P>0.05)).4.During the whole growth period of alfalfa,low nitrogen treatment(N1)significantly increased partial productivity compared with N2 and N3.In conclusion,45 kg/hm^(2) was the best nitrogen application rate for alfalfa production in Horqin Sandy land.This study can provide reference for alfalfa productivity improvement and nitrogen efficient utilization.