We investigated the variation of denitrifying communities in rice rhizosphere at tillering and booting stages in comparison with bulk soils with a pot experiment. The techniques of quantitative polymerase chain reaction (qPCR) and terminal restriction fragment length polymorphism (T-RFLP) were used to measure the abundance and community composition of denitrifiers (narG and nosZ), respectively. The results showed that the potential denitrification activity in the rhizosphere at tillering stage was significantly lower than bulk soils. No significant difference was detected between the rhizosphere and bulk soils at booting stage. The abundance of both narG- and nosZ-containing denitrifying bacteria was significantly higher in rhizosphere than in bulk soils at both tillering and booting stages. In comparison with narG-containing community, community composition and diversity of nosZ-containing bacteria were more sensitive to rice growth. In conclusion, the exudates of rice could induce significantly more denitrifying bacteria in rhizosphere, whose denitrifying activities were related to growth stage of rice. At the period with strong growth, the secretion of roots showed clear restriction to the functions of rhizospheric denitrifiers compared to booting stage.
通过水稻盆栽试验,分别于水稻分蘖期和孕穗期采集根际与非根际土壤,利用末端限制性片段长度多态技术(T-RFLP)和实时荧光定量PCR(qPCR)技术探究水稻生长对根际反硝化作用和反硝化微生物的影响.结果表明: 分蘖期根际土壤的反硝化势显著低于非根际土壤,而孕穗期根际与非根际土壤的反硝化势没有显著性差异.但分蘖期和孕穗期根际土壤中含narG和nosZ基因的微生物数量均显著高于非根际土壤,其中含nosZ基因的反硝化微生物的群落组成结构和多样性对根际环境响应更敏感.说明虽然水稻根系生长会刺激反硝化微生物的生长繁殖,但抑制了根际土壤中一些反硝化微生物的活性,从而降低了根际土壤的反硝化潜势.
Keywords: community composition; denitrification; narG; nosZ; potential denitrification activity; rhizosphere.