不同土壤肥力水平下施氮对甘薯产量与氮肥利用率的影响

为探明不同土壤肥力条件下施用氮肥对甘薯产量和氮肥利用率的影响,选取鲜食型甘薯品种烟薯25号为试验材料,采用大田试验,研究了施氮对不同土壤肥力下甘薯产量及产量构成因素、干物质积累规律和氮肥利用率的影响。结果表明:不施氮条件下,甘薯蔓数、最大蔓长度、叶面积指数和产量均表现为高肥力中肥力低肥力(P0.05)。3种土壤肥力条件下,增施氮肥均能显著增加甘薯蔓数、最大蔓长度和叶面积指数(P0.05),但对最大蔓节间数影响不显著。高肥力、中肥力和低肥力地块分别在施氮量为50,100,150kg/hm~2时获得最高产量,分别较不施氮处理(N0)增产16.06%,29.63%和33.33%。与地力条件无关,增施氮肥均能提高甘薯地上部干物质累积量。中、低土壤肥力条件下,甘薯氮累积量随施氮量增加逐渐增加,而高土壤肥力条件下呈先增加后降低的趋势;高肥力地块氮肥利用率随施氮量增加而逐渐降低,中肥力地块先增加后逐渐降低,在100kg/hm~2时氮肥利用率最高,低肥力地块逐渐增加。综合产量和氮肥利用率,可知高肥力、中肥力和低肥力地块甘薯适宜施氮量分别为50,100,150kg/hm~2。

Effects of Nitrogen Application on Yield and Nitrogen Use Efficiency of Sweet Potato Under Different Soil Fertility

Effects of different nitrogen application rates on sweet potato yield and nitrogen use efficiency under different soil fertility conditions were explored.Field experiments were carried out to investigate the effects of nitrogen fertilizer on yield,yield components,dry matter accumulation and nitrogen use efficiency of Yanshu25,under different soil fertility levels.As results showed,without nitrogen fertilizer,the number of branches,the length of the longest stem,the leaf area index,and the yield were following this order:highsoil fertility＞middle soil fertility＞low soil fertility,and the differences were significant.Nitrogen fertilizer could increase the first three indices under three soil fertility conditions (P＜0.05),but had no significant effect on the number of the largest internodes.Field plots with high,middle and low fertility levels gained the largest yields when nitrogen fertilizers were 50,100,and 150 kg/hm2,respectively,which increased by 16.06％,29.63％ and 33.33％,respectively,compared to the control.Besides,nitrogen fertilizer could increase accumulation of above-ground dry matter s of sweet potato under all soil fertility levels.Lastly,with the increasing of nitrogen addition,the nitrogen accumulation were increased for middle and low fertility of plots,but first increased and then decreased for high fertility of plots.With the increasing nitrogen application rates,nitrogen use efficiency decreased under the high fertility,while increased under the low fertility,and was the highest under the middle fertility with 100 kg/hm2.The optimum nitrogen application rates for sweet potato in high,middle and low soil fertility are 50,100 and 150 kg/hm2,respectively.