作物轮作对多年连作棉田土壤细菌群落结构的影响

Effects of crop rotation on soil bacterial community structure in multi-year continuous cropping cotton fields

新疆棉田连作问题突出,作物轮作是缓解棉田连作障碍的有效措施。通过对长年连作棉田轮作苜蓿、大豆、花生等六种作物后土壤进行细菌群落结构分析,评价六种作物对棉田土壤微生态的影响程度,筛选能够显著改善提升连作棉田土壤微生态的作物。结果表明:大豆、花生、苜蓿三种豆科作物根际的土壤细菌群落结构与棉花相似性较高,对棉田土壤细菌ACE指数、Chao1指数虽有提升但无显著差异。而番茄、玉米、甜菜三种作物对棉田土壤细菌群落结构影响较大,显著降低了棉田土壤细菌Alpha多样性及不同分类水平细菌种群的数量。在物种组成方面,变形菌门(Proteobacteria)、放线菌门(Actinobacteria)和酸杆菌门(Acidobacteria)为土壤中优势细菌门,变形菌门在番茄根际土壤的丰度最高(58.4%),在苜蓿根际最低(40.5%);放线菌门在苜蓿根际丰度最高(15.8%),在番茄根际最低(6.5%);酸杆菌门在大豆根际丰度最高(10.2%),在番茄根际最低(5.5%)。土壤中显著差异细菌种群主要富集在苜蓿、大豆根际,但是不同作物单季轮作未对土壤中主要有益细菌种群的相对丰度产生显著影响。综合看,大豆、花生、苜蓿三种豆科作物单季轮作对棉田土壤细菌群落结构的影响较小;番茄、玉米和甜菜能够显著降低棉田土壤细菌多样性和种群数量,其中甜菜的影响作用最显著。

Xinjiang cotton fields have a serious of problems on continuous cropping;crop rotation is an effective measure to alleviate the obstacle.High-throughput sequencing was carried out on the soil of alfalfa,soybean,peanut,tomato,corn and sugar beet in rotation continuous cropping cotton fields,and effects of six crops on the soil microecology in cotton fields were evaluated in terms of the changes of soil bacterial community structure,screening crops that could significantly improve the soil microecology in continuous cropping cotton fields.The results showed that the bacterial community structure in the rhizosphere soil of soybean,peanut and alfalfa was similar to that of cotton;the ACE index and Chao1 index of soil bacteria in rhizosphere soil of soybean,peanut and alfalfa were increased but there was no significant difference with cotton.While tomato,corn and sugar beet had a greater effect on soil bacterial community structure in field,the bacterial population number and ALPHA diversity in the rhizosphere soil of tomato,corn and sugar beet were significantly lower than those of cotton.In terms of species composition,Proteobacteria,Actinobacteria and Acidobacteria were dominant phyla in soil.Among them,the abundance of Proteobacteria in tomato rhizosphere soil was the highest(58.4%),and that in alfalfa rhizosphere was the lowest(40.5%).The abundance of Actinomycetes in alfalfa rhizosphere was the highest(15.8%)and in tomato rhizosphere was the lowest(6.5%).Soybean rhizosphere had the highest abundance of Acidobacteria which was 10.2%,and tomato rhizosphere had the lowest at 5.5%.The significantly different bacterial populations were mainly concentrated in the rhizosphere of alfalfa and soybean,but the short-term rotation had no significant effect on the relative abundance of the main beneficial bacterial populations in the soil.In conclusion,short-term rotation of soybean,peanut and alfalfa had little effect on soil bacterial community structure in cotton field.However,tomato,corn and sugar beet could significantly reduce soil bacterial diversity and population number in cotton field,among which sugar beet had the greatest effect.