烟草连作对土壤微生物多样性及酶活性的影响

Effects of Continuous Tobacco on Soil Microbial Diversity and Enzyme Activities

对采自襄城县连作1a-8a的烟田土壤的微生物数量、细菌多样性和土壤中的蔗糖酶、淀粉酶、纤维素酶和进行了测定。结果表明:随着连作年限的增加,土壤细菌和放线菌数量呈明显下降趋势,而真菌数量变化表现出一定的滞后性,呈现升高—降低—升高—降低的波动;土壤细菌的Shannon指数、Simpson指数和McIntosh多样性指数整体呈下降趋势,仅在连作5a时出现一定的上升波动,与土壤细菌的分离培养结果相吻合;土壤蔗糖酶和淀粉酶活性先升高后降低,连作2a时达到最大值,当连作年限﹥3a时,酶活性变化不大,都处于较低水平;而土壤纤维素酶活性在连作1a-3a时便剧烈下降,连作年限﹥2a时,酶活性维持在较低的水平。烟草长期连作对土壤微生物的多样性和土壤酶活性的影响,不利于土壤生态系统的健康发展。图5,表1,参28。

Soil samples were collected from continuous cropping 1a- 8a（ except 7 year） tobacco fields in Xiangcheng county,and the amount of soil microbial,bacteria diversity,activities of sucrase,amylase,pectase cellulase were determined. Results showed that with the increasing of continuous cropping year,the number of soil bacteria and actinomycetes was going down,while the number of soil fungus kept the trend of＂up- down- up- down＂. The bacterial diversity index as estimated by DGGE banding patterns,e. g. Shannon,Simpson and McIntosh index had the same trend of falling down,but had a slight rise in the fifth continuous cropping year that consistenting with the results of soil bacteria isolation. The changes of invertase and amylase activity revealed increased at the begaining and reached a peak in second continuous cropping year and then decreased. When the continuous cropping year is greater than 3 years,the invertase and amylase activities changed a little and then kept at a lower level. Meanwhile,the cellulase activity declined violently within 1- 3continuous cropping years,and kept at a lower levels when the continuous cropping term more than 2 years. The impact of tobacco continuous cropping on soil microbial diversity and soil enzyme activities csused the disadvantage of healthy soil ecosystem development.