小麦-蚕豆间作条件下氮肥施用量对根际微生物区系的影响

通过田间小区试验，研究了小麦/蚕豆间作条件下4种施氮水平(0、90、180和270 kg·hm^-2)对根际微生物区系和多样性的影响.结果表明：在整个生育期，微生物数量有一定的波动，但均以开花期数量最高.与单作相比，间作显著增加了小麦和蚕豆根际的细菌、真菌、放线菌数量和微生物总量，而显著降低了开花期和成熟期蚕豆根际的微生物多样性.在不施氮（N₀）和低氮（N₉₀）水平下，间作与单作在微生物数量上的差异较大.间作对土壤微生物数量的促进效应在分蘖期和开花期最大，成熟期显著降低.小麦根际的微生物数量随施氮量的增加先增加后降低，以常规施氮处理（N₁₈₀）的微生物数量最多，氮肥用量对单作小麦的影响大于间作小麦. 施氮量对蚕豆根际细菌、真菌、放线菌数量和微生物多样性无显著影响，但降低了间作蚕豆根际微生物总量.适量施用氮肥能有效调节根际微生物区系，间作系统地上部植物多样性与地下部微生物区系间存在紧密联系.

Effects of nitrogen application rate on rhizosphere microbial community in wheat-faba bean intercropping system.

With field plot experiment, this paper studied the effects of different nitrogen application rate (0, 90, 180 and 270 kg x hm(-2)) on the rhizosphere microbial community and its diversity in wheat-faba bean intercropping ecosystem. The results indicated that the amount of rhizosphere microbes fluctuated with crop growth stages, being the highest at the flowering stage of test crops. Comparing with monocropping, intercropping significantly increased the total amount of microbes and the numbers of bacteria, fungi and actinomyces in the rhizosphere of both wheat and faba bean, but decreased the microbial diversity in the rhizosphere of faba bean at its flowering and maturing stages. Under no nitrogen and low nitrogen application rate, a larger difference was observed in the amount of rhizosphere microbes between intercropping and monocropping. The promotion effect of intercropping in increasing the amount of rhizosphere microbes was more apparent at tillering and flowering stages, but declined significantly at maturing stage. With increasing nitrogen application rate, the amount of microbes in wheat rhizosphere increased first and decreased then, with the peak appeared at 180 kg N x hm(-2), and the effect was more obvious on monocropped wheat than on intercropped one. Nitrogen application rate had no significant effects on the numbers of bacteria, fungi and actinomyces and the microbial diversity in faba bean rhizosphere, but decreased the total amount of microbes in the rhizosphere of intercropped faba bean. Rational nitrogen application could regulate rhizosphere microbial community effectively, and there was an obvious correlation between aboveground plant diversity and belowground microbial community.