胡椒连作对土壤微生物群落功能多样性与群落结构的影响

连作障碍严重威胁中国胡椒优势种植区可持续发展,而土壤微生物多样性下降、群落结构失衡是连作障碍形成的重要原因之一。为了探明胡椒连作障碍与微生物多样性及群落结构变化之间的关系,揭示胡椒连作障碍形成的微生物机理,本文采用BIOLOG微平板法研究了海南万宁8、18和28 a 3种不同种植年限胡椒园土壤微生物群落功能多样性和群落结构变化。结果表明:随种植年限增加,不同园块之间稳定并达到最大的平均吸光度值(AWCD)呈明显下降趋势;香农指数、香农均匀度等多样性指数亦随种植年限增加呈显著下降趋势,而辛普森优势度指数无显著性差异;微生物群落结构随着年限增加出现了2次明显变化,第1次群落结构变化发生在8~18 a阶段,主要与酚酸类和多聚物类碳源利用微生物大幅减少有关,第2次则发生在18~28 a阶段,与碳水化合物类、氨基酸类、羧酸类和胺类相关利用微生物减少有关。因此,胡椒连作显著降低了土壤中微生物多样性,改变了微生物群落结构,是胡椒连作障碍形成的重要原因之一。

Effects of Consecutive Monoculture of Piper nigrum L. on Soil Microbial Functional Diversity and Community Structure

Consecutive monoculture induces black pepper (Piper nigrum L.) poor growth, low yield, and serious soil-borne disease, thus becomes one of the most serious threats to the sustainable development of black pepper industry in China. To investigate its microbiological formation mechanisms, the soil samples from black pepper orchards with consecutive monoculture for 8, 18 and 28 years were analyzed by using the BIOLOG EcoPlates method and the responses of soil microbial functional diversity and community structure to different planting ages were demonstrated as follow. It revealed that average well color development ( AWCD) obviously decreased with increasing planting duration. The same tendency was also demonstrated in soil microbial diversity indices, such as Shannon index, Shannon evenness index and Simpson index. In addition, the utilization of carbon sources by soil microbes from different planting duration showed significantly different. For example, the utilization rates of phenolic compounds and polymers obviously decreased during the period from the 8 th year to the 18th year and those of carbohydrates, amino acids, carboxylic acids and amines obviously decreased from the 18th year to the 28th year, which indicating the soil microbial community structure experienced two obvious changes with planting duration increasing. Furthermore, the principal component analysis ( PCA) also showed the soil samples from the three planting duration were clearly separated from each other. These results suggested that consecutive monoculture of P. nigrum L. could decrease soil microbial activity and diversity, change the soil microbial community.