种植方式对玉米不同生长期土壤微生物群落功能多样性的影响

为探讨玉米不同种植方式下土壤微生物群落功能多样性的差异,进行田间定点试验,采用Biolog方法分别研究了4行轮作、4行连作、8行轮作和8行连作的种植方式对玉米种植前、拔节期、抽穗期和收获期土壤微生物功能多样性的影响。结果表明:4种种植方式的土壤微生物均在种植前代谢活性最弱、功能多样性最低,在玉米抽穗期土壤微生物代谢活性最强,功能多样性最高。在种植玉米前,轮作的土壤微生物代谢活性和功能多样性高于连作,8行轮作和4行轮作土壤微生物的物种多样性指数分别比相应的连作高22.93%和11.42%;4行轮作的土壤微生物物种多样性指数比8行轮作低3.17%,而4行连作比8行连作高6.83%。在玉米拔节期、抽穗期及收获期连作土壤微生物功能多样性略高于轮作,且有4行连作大于8行连作的趋势,但差异均未达显著水平。种植前,4种种植模式的土壤微生物对6大类碳源的利用程度整体上都较低,降解碳水化合物类、羧酸类和聚合物类碳源的微生物是种植方式影响的主要土壤微生物类群;随着玉米的生长,土壤微生物对6大类碳源的利用都逐渐增强,玉米拔节期、抽穗期和收获期之间土壤微生物特征碳源没有较大差异,4种种植方式的土壤微生物对聚合物类碳源利用程度差异都不显著。PLS-EDA分析结果表明种植方式对土壤微生物产生较大影响,种植前8行轮作和4行连作的土壤微生物碳源利用模式具有相似性;种植玉米后4种种植方式的土壤微生物对碳源的利用模式存在较大差异,其中4行连作的土壤微生物在玉米拔节期和收获期对碳源的利用模式与其他3种种植方式差异最大。试验说明作物长期连作栽培会影响土壤微生物群落功能,降低土壤微生物物种多样性,引起土壤微生物群落结构与功能的失调。

Analysis of functional diversity of soil microbial communities under different cultivation patterns at different growth stages of maize

In order to explore the differences in metabolic functional diversity of soil microbial communities under different cultivation patterns of maize, a fixed-point experiment was carried out and the field investigation and Biolog analysis used to study metabolic activity and functional diversity of soil microbial community under 4 cultivation patterns of maize. The investigated cultivation patterns included annual rotation of 4 rows maize with potato (R4), 4 rows maize continuous cropping (C4), annual rotation of 8 rows maize with potato (R8) and 8 rows maize continuous cropping (C8). A total of 4 growth stages of maize (pre-planting, jointing, heading and harvest stages) were studied. The results showed that both metabolic activity and functional diversity of soil microbial communities were lower at pre-planting stage, and higher at heading stage of maize. Metabolic activity and functional diversity of soil microbial community under rotation cropping were higher than those under continuous cropping at pre-planting stage of maize. The Shannon-Wiener index of soil microbial under R8 and R4 was 22.93% and 11.42% higher than that under C8 and C4, respectively. Meanwhile the Shannon-Wiener index of soil microbial under R4 was 3.17% lower than that under R8. However, the Shannon-Wiener index of soil microbial under C4 was 6.83% higher than that under C8. The functional diversities of soil microbial communities at jointing, heading and harvest stages of maize under continuous cropping patterns were slightly higher than those under rotation cropping patterns, and higher under C4 than under C8, though the differences were not significantly. Before planting, the overall utilization degree of 6 categories of carbon sources by soil microbial communities under 4 planting patterns was low. The main microbial populations impacted by planting patterns were those decomposing carbohydrates, carboxylic acids and polymers before maize planting. With the growth of maize, the ability of microbial communities to metabolize 6 categories carbon substrate gradually increased, and peaked at heading stage. Also characteristic carbon resources at jointing, heading and harvest stages were similar. Differences in the utilization of polymers by soil microbial communities under different planting patterns were insignificant. PLS-EDA analysis showed that the ability of soil microbial communities to utilize carbon source was significantly different under different cultivation patterns. Before planting, soil microbial communities under R8 and C4 were similar in terms of carbon utilization. However, Soil microbial communities under 4 different cultivation patterns had distinctly different modes of utilization of carbon sources after planting of maize. Especially, carbon utilization of soil microbial communities under C4 was significantly different from that of the other three cultivation patterns at jointing and harvest stages of maize. It showed that continuous cropping of maize influenced the functionality of soil microbial community and reduced soil microbial species richness. This resulted in structures disorder and functions loss of soil microbial community.