Effect of Different Fertilizers on Functional Diversity of Microbial Flora in Rhizospheric Soil Under Tobacco Monoculture

Continuous cropping obstacle is one the most important problems in tobacco (Nicotiana tabacum L.) production. To alleviate continuous cropping obstacle based on management of soil ecology, the effects of different fertilizers were tested using tobacco cultivar K326 growing in a field with 12-year consecutive cultivation. The rhizospheric soil was sampled to investigate the changes in functional diversity of microbial flora in different treatments. The results showed that the autotoxic allelopathic potential was maximal for the monoculture soil treated with traditional compound fertilizer, and minimal for the soil treated with farmyard manure. According to the result of BIOLOG analysis, traditional compound fertilizer was conducive to the growth of microbial flora feeding on amino acids and amine as carbon sources, the commercial organic fertilizer to the growth of microbial flora using carboxylic acids as a carbon source, and farmyard manure to the growth of microbial flora using carbohydrate, fatty acids, and phenolic acids as carbon sources. Principal component analysis indicated that the first 2 components were related to carbon sources, which accounted for 74.37% and 25.63% of the data variation. The carbon source of carbohydrate, fatty acids, and phenolic acids mainly contributed to the separation of the 2 principal components. The autotoxic allelopathic potential of tobacco rhizospheric soil was positively correlated with the average well color development (AWCD) value of microbial flora feeding on carbohydrate and phenolic acids as carbon sources, and negatively correlated with that of the microbial flora using the carbon source of fatty acids. In addition, for the growth of microbial flora in monoculture soil, farmyard manure was the best, followed by commercial organic fertilizer, and traditional compound fertilizer was the worst.

摘 要烟草连作障碍是制约烟草产量与品质的关键因素。以连作12年的烟草土壤为对象, 施用不同肥料, 调查施肥后的土壤对连作烟草作物的生长、土壤微生物功能多样性的影响及其对土壤化感自毒的调节作用。结果表明, 烟草根际土壤化感自毒潜力以施用常规复合肥最大, 施用农家肥最小。基于BIOLOG平板法的微生物功能多样性研究表明, 施用常规复合肥利于氨基酸类、胺类物质为碳源的微生物生长; 施用有机肥利于羧酸类物质为碳源的微生物生长; 而施用农家肥则利于糖类、脂肪酸、酚酸类物质为碳源的微生物生长。土壤微生物利用单一碳源的主成分分析结果表明, 与碳源利用相关的主成分1、主成分2可分别解释变量方差的74.37%和25.63%。在主成分分离中有主要贡献的是糖类、脂肪酸类、酚酸类碳源。相关性分析结果显示, 烟草土壤的化感自毒潜力与以糖类和酚酸类物质为碳源的微生物AWCD值呈显著正相关, 而与以脂肪酸类物质为碳源的微生物AWCD值呈显著负相关。此外, 农家肥施用最利于微生物生长, 有机肥次之, 常规复合肥最差。