烤烟连作对耕层土壤酶活性及微生物区系的影响

摘要

以烤烟品种“龙江911”为材料,在大田试验条件下分别测定了连作1年和5年的烤烟耕层土壤酶活性及微生物区系变化.结果表明:烤烟连作1年的耕层土壤酸性磷酸酶与脲酶活性高于正茬(大豆-小麦-烤烟),而烤烟连作5年的土壤酸性磷酸酶与脲酶活性低于连作1年.在0～ 10cm土层内,烤烟连作1年和连作5年的土壤过氧化氢酶活性均比正茬低,且连作5年土壤比连作1年土壤降低了35.47％.10～20 cm土层内,烤烟连作1年和5年的土壤蔗糖酶活性分别比正茬降低了30.27％和52.14％.烤烟连作减少了土壤细菌和放线菌数量,增加了真菌数量,细菌主要以土壤氨化细菌、好气性自生固氮菌和好气性纤维素分解菌降低为主.因此,烤烟连作破坏了微生物种群的平衡及降低土壤酶活性可能是引起烤烟连作障碍的主要原因之一.%Using flue-cured tobacco variety "Longjiang 911" as test material, this paper studied the variations of soil enzyme activities and microbial flora in different arable layers (0-10 cm and 10-20 cm) under continuous cropping of flue-cured tobacco for 1 and 5 in field experimental conditions. The results showed that activities of acidic phosphatase and urease in soil for la-continuous cropping was enhanced compared to rotational cropping (soybean-wheat- tobacco), but decreased significantly for 5a-continuous cropping. Soil catalase activity of Sa-continuous cropping decreased by 35.47% compared with la-continuous cropping in 0-10 cm layer. The soil sucrase activities of flue-cured tobacco continuous cropping for la and 5a showed a greater decrease trend in 0-20 cm layer, which decreased by 30.27% and 52.14% respectively compared to the rotational cropping. Continuous cropping of flue-cured tobacco decreased the numbers of soil bacteria and actinomyces while increased the numbers of soil fungi. The amounts of ammonifying bacteria, aerobic azotobacter and anaerobic cellulose-decomposer decreased for 5a-continuous cropping compared to la continuous cropping. Thus, the balance destruction of soil microbial communities and decreases of soil enzyme activity could be attributed to one of the reasons for the continuous cropping obstacle in flue-cured tobacco production.