应用^(15)N示踪法研究马铃薯燕麦间作对氮素吸收利用的影响

Impact of potato-oat intercropping on nitrogen uptake and utilization by^(15)N tracer method

【目的】探明宁夏南部山区马铃薯与燕麦间作复合系统氮素吸收利用特性。【方法】试验采用随机区组设计,设置马铃薯单作、燕麦单作、马铃薯间作燕麦3个处理,另外在试验小区内设置了^(15)N示踪微区,进行^(15)N同位素丰度测定。【结果】间作提高了马铃薯对肥料氮的吸收和积累而降低了燕麦的吸收和积累,追施氮肥,间作马铃薯叶、茎、块茎部位^(15)N原子百分超相对单作分别增加56.6%、61.2%、173.2%,间作燕麦叶、茎、穗部位^(15)N原子百分超相对单作分别减少37.7%、53.9%、44.0%;基施氮肥,间作马铃薯叶、茎、块茎器官Ndff相对单作分别增加55.4%、60.6%、170.0%,间作燕麦叶、茎、穗各器官Ndff相对单作分别减少23.1%、21.5%、26.2%;间作提高了马铃薯块茎氮素积累量而降低了燕麦穗氮素积累量,在氮肥基施和追施条件下,间作马铃薯块茎^(15)N积累量相对单作分别提高了2.98%和0.02%;间作燕麦穗^(15)N积累量相对单作分别降低了0.35%和0.20%;间作提高了马铃薯和燕麦生殖器官所吸收的土壤氮比例。【结论】间作处理有利于马铃薯各器官的建成,处于氮素营养竞争优势地位,间作促进了马铃薯块茎和燕麦穗对土壤氮的吸收,从而提高了系统整体氮素利用。

【Objective】This research aimed to investigate the nitrogen uptake and utilization characteristics in a potato-oat intercropping system in the southern mountainous area of Ningxia.【Method】A randomized block design was established,with three treatments:potato monoculture,oat monoculture,and potato intercropped with oats.A^(15)N tracer microzone was established within the experimental plot to determine the abundance of the^(15)N isotope.【Result】Intercropping increased the absorption and accumulation of fertilizer nitrogen by potatoes while decreasing the absorption and accumulation of oats.With the application of topdressing nitrogen fertilizer,the^(15)N atomic percentage in intercropped potato leaves,stems,and tubers increased by 56.6%,61.2%,and 173.2%,respectively,while the^(15)N atomic percentage in intercropped oat leaves,stems,and spikes decreased by 37.7%,53.9%and 44.0%,respectively.The nitrogen derived from fertilizer(Ndff)in the leaves,stems,and tubers of intercropped potatoes increased by 55.4%,60.6%and 170.0%,respectively,compared to monoculture.Conversely,the Ndff in the leaves,stems,and ears of intercropped oats decreased by 23.1%,21.5%and 26.2%,respectively,compared to monoculture.Intercropping enhanced nitrogen accumulation in potato tubers while reducing nitrogen accumulation in oat ears.Under conditions of basal and topdressing nitrogen fertilizer,the^(15)N accumulation in intercropped potato tubers increased by 2.98%and 0.02%,respectively,compared to monocropping.The^(15)N accumulation in oat ears of intercropped oats decreased by 0.35%and 0.20%,respectively,compared to monoculture.Intercropping also increased the proportion of soil nitrogen absorbed by the reproductive organs of potatoes and oats.【Conclusion】Intercropping treatment favors the development of potato organs and provides a competitive advantage in terms of nitrogen nutrition.Intercropping promotes the absorption of soil nitrogen by potato tubers and oat ears,thereby improving the overall nitrogen utilization of the system.