休耕对连作障碍植烟土壤酶活性及细菌群落结构的影响

Effects of lying fallow on enzyme activities and bacterial community structures in tobacco-planting soils with continuous cropping obstacles

为揭示休耕对连作障碍土壤微生态环境的影响机制,选择常年连作烟草且青枯病发生严重的烟田为研究对象,研究了休耕对土壤酶活性及土壤细菌群落结构的影响。结果表明,休耕措施能有效提高连作烟田有机质、碱解氮含量和土壤酶活性,特别是休耕两年后土壤蔗糖酶、过氧化氢酶活性比未休耕烟田分别增加147.85%、64.13%。休耕措施有利于提高土壤细菌群落的丰富度,随着休耕年限的增加Chao指数与Shannon指数呈增加趋势,Simpson指数呈降低趋势。休耕后土壤中的有益菌酸杆菌门(Acidobacteria)和有益菌玫瑰弯菌属(Roseiflexus)均明显高于连作烟田,而致病菌青枯雷尔氏菌则明显低于连作烟田。休耕一年、两年的烟田青枯病发病率比连作烟田分别降低22.62%和32.55%。因此,休耕能改善连作障碍植烟土壤的微生态环境,提高土壤肥力,降低烟田青枯病的发病率。

To investigate possible mechanisms of lying fallow on the microecological environment of soils with continuous cropping obstacles, the effects of lying fallow on the enzyme activities and bacterial community structure in soils was studied in continuous tobacco cropping fields with severe bacterial wilt. The results showed that lying fallow effectively promoted the contents of organic matter, alkali-hydrolyzed nitrogen and enzyme activities in soils. Especially after two fallow years, soil invertase and catalase activities increased by147.85% and 64.13% respectively, as compared with continuous tobacco cropping. Lying fallow was beneficial to promote the abundance of bacterial community in soils. With the increase of fallow years, Chao index and Shannon index increased, while Simpson index decreased. The relative abundances of beneficial bacteria Acidobacteria and Roseiflexus were significantly higher, while that of pathogenic bacteria Ralstonia was significantly lower in the fields after lying fallow than in continuous tobacco cropping fields. The incidence of bacterial wilt in tobacco fields lying fallow for one or two years was lower by 22.62% or 32.55% than that in continuous tobacco cropping fields, respectively. Therefore, lying fallow improves the microecological environment and fertility of tobacco-growing soils with continuous cropping obstacles and reduces the incidence of bacterial wilt.