三七收获后不同年限土壤微生物代谢多样性分析

采用Biolog技术,对云南省砚山县的盘龙、阿猛、干河3个乡镇进行了三七历年种植地的调查研究,以未种植过三七的土壤为对照,研究三七收获后1~6 a不同年限对土壤养分、土壤微生物对碳源利用以及土壤微生物多样性的影响。结果表明,反映土壤微生物活性的平均颜色变化率(AWCD)并未随年限增加呈现明显变化规律;微生物培养96 h活性旺盛。对Biolog板31种碳源吸光度值聚类分析表明,3个乡镇所取三七收获后1 a和6 a土壤微生物碳源利用均可聚为一类,其土壤微生物碳源利用特征相似,其余不同年限土壤微生物碳源利用聚类并未出现一定规律;与未种植过三七的土壤相比,三七收获后1 a、6 a土壤微生物均对碳水化合物类、聚合物类、羧酸类和酚类碳源的利用分别高出25.97%~55.59%和53.14%~65.68%;随着三七收获后年限的增加,土壤微生物对碳水化合物、氨基酸类、羧酸类碳源利用呈收获后2 a升高、4 a和5 a下降趋势。收获三七后1~6 a土壤与未种植过三七的土壤相比,氮、磷、钾及有机质含量差异均不显著。除干河乡外,阿猛乡和盘龙乡收获三七后1~6 a土壤微生物与未种植过三七的相比,Shannon-Wiener指数、丰富度指数、Simpson指数均值总体差异不明显。试验说明三七轮作至少需6 a以上时间,土壤微生物对不同碳源的优势利用可反映出三七连作障碍与土壤微生物群落结构差异有密切联系。

Soil microbial diversity analysis after different years of Panax notoginseng harvest

Continuous cropping obstacle is a key limit factor of Panax notoginseng cultivation. The reason for continuous cropping obstacles, such as changes of soil microorganisms have not been clearly, especially under natural conditions. To evaluate the impact of P. notoginseng planting on soil microbial communities and continuous cropping obstacle mechanisms, the soil nutrients and soil microorganism community structure were investigated in different fields after different years of P. notoginseng harvested in three towns (Ganhe, A’meng and Panlong) in Wenshan City, Yunnan Province. In each town, 7 fields were selected as soil sampling sites. Seven fields were planted other corps rather than P. notoginseng, six of which were at 1 to 6 years after P. notoginseng harvested, the other one which never planted P. notoginseng was set as the control (CK). Biolog-ECO method was used to analyse the average well color development (AWCD) and diversity of microbial community to explore microbial community dynamics. The results showed that AWCD of soil microorganisms was not regularly changed with increasing years after P. notoginseng harvested. After cultivated for 96 hours, activity of soil microorganisms reached the highest level. Cluster analysis of utilization of 6 groups (31 kinds) of carbon resources showed that in three towns, carbon resources utilization of soils at 1 and 6 years after P. notoginseng harvested were classed in one group, indicting the same characteristics of carbon resources utilization. No obvious regularity was observed for other years. The use of carbohydrates, polymeric substances, carboxylic acid and phenols by soil microorganisms in 1 and 6 years after P. notoginseng harvested were 25.97%-55.59% and 53.14%-65.68% more than those of CK. Soil nitrogen, phosphorus, potassium and organic matter contents increased at 2 years, decreased at 4 and 5 years after P. notoginseng harvested. Soil nitrogen, phosphorus, potassium and organic matter contents in three towns, as well as Shannon-Wiener index, evenness index and Simposon’s index of soil microorganisms in A’meng and Panlong Towns at 1 to 6 years after P. notoginseng harvested were not significantly different compared with that of CK. The results suggested that rotation with other crops at least for 6 years was indispensable to avoid continuous cropping obstacles of P. notoginseng.