冬季覆盖作物秸秆还田对双季稻田根际土壤微生物群落功能多样性的影响

微生物群落功能多样性是土壤质量变化重要的指标,不同作物类型的秸秆还田措施对土壤微生物群落功能多样性具有明显的影响。以位于双季稻主产区不同冬季覆盖作物-双季稻种植模式大田定位试验田为研究对象,以冬闲-双季稻种植模式为对照(CK),应用Biolog-GN技术开展黑麦草-双季稻(Ry)、紫云英-双季稻(Mv)、油菜-双季稻(Ra)和马铃薯-双季稻(Po)种植模式条件下不同冬季覆盖作物秸秆还田后对双季稻田根际土壤微生物功能多样性影响的研究。研究结果表明,早稻和晚稻成熟期,与CK处理相比,冬季覆盖作物秸秆还田处理增加了稻田土壤碳源平均颜色变化率(AWCD),以Po处理AWCD均为最高,均显著高于Ry和CK处理。不同冬季覆盖作物秸秆还田处理土壤微生物代谢多样性指数表现出明显的差异,早稻成熟期,Po处理的Richness、Shannon和McIntosh指数均为最高,其次为Ry、Mv和Ra处理,CK处理最低;晚稻成熟期,各处理的Richness、Shannon和McIntosh指数大小顺序均表现为PoRaMvRyCK。土壤微生物碳源利用的主成分分析结果表明,各冬季覆盖作物秸秆还田处理根际土壤微生物利用的主要碳源为氨基酸类和糖类物质,不同处理间碳源利用类型有差异。冬季覆盖作物秸秆还田措施有利于提高双季稻田根际土壤微生物对碳源的利用能力、物种丰富度和均匀度。

Effects of recycling straw of different winter covering crops on rhizospheric microbial community functional diversity in a double-cropped paddy field

Microbial community functional diversity is a sensitive indicator of soil quality; soil management such as different methods of recycling crop straw can affect the microbial community functional diversity of paddy soils. In order to clarify the effects of returning different winter covering crop straw types to the paddy field on the rhizospheric microbial community functional diversity of paddy soils in a double-cropping rice region, this study used different winter covering crops and double-cropping rice patterns as research objectives to analyze the effects of returning five types of winter covering crop straw to the paddy field on the rhizospheric microbial community functional diversity in paddy soils in a small-plot experiment in a paddy field. Five winter covering crops and double-cropping rice combinations were used:ryegrass (Lolium multiflorum L.)-double cropping rice (Ry), Chinese milk vetch (Astragalus sinicus L.)-double cropping rice (Mv), rape (Brassica napus L.)-double cropping rice (Ra), potato (Solanum tuberosum L.)-double cropping rice (Po), and fallow-double cropping rice (CK) as control. In this paper, the average well color development (AWCD) in Biolog-GN plates indicated the capacity for carbon utilization by the rhizospheric microbial community. We analyzed the rhizospheric microbial community functional diversity of the paddy soils with the above five treatments, which was detected using the Biolog-GN system. The results showed that applications of winter covering crop straw returned to the paddy field caused high increases in the AWCD compared with the CK treatment, and the AWCD of Po treatment was greater than those of the Ry and CK treatments at early and late rice maturity stages. It was concluded that applications of winter covering crop straw returned to the paddy field resulted in a change in the carbon utilization efficiency of the rhizospheric soil microbial community. There were differences in the genetic diversity indices of the rhizospheric soil microbial communities among the different recycled straw of winter covering crop treatments at early and late rice maturity stages. The richness, Shannon, and McIntosh indices under different recycled straw of winter covering crop treatments were significantly different, with those of Po treatment the highest and those of CK treatment the lowest, at the early rice maturity stage. The richness, Shannon, and McIntosh indices under different recycled straw of winter covering crop treatments were ordered as follows at the late rice maturity stage:Po > Ra > Mv > Ry > CK. Principal component analysis (PCA) of substrate reactions were analyzed in the present study. The results indicated that there were different carbon substrate utilization patterns among different recycled straw of winter covering crop treatments, and that carbohydrates and amino acids were the main carbon resources in rhizospheric microbe utilization. There were significant differences in carbon substrate utilization patterns in different recycled straw of winter covering crop treatments. Therefore, the application of winter covering crop straw returned to the paddy field could significantly increase the utilization of carbon sources by rhizosphere microorganisms, species richness, and species evenness in double-cropping rice regions.