清水苜蓿土壤浸提液对连作马铃薯根际土壤环境酶活性和微生物群落的影响

Effects of rhizosphere soil extract of Qingshui alfalfa (Medicago sativa L.) on enzyme activities and microbial communities in rhizosphere soil of continuous cropping potato

为缓解马铃薯连作障碍,以新大坪马铃薯为供试材料进行盆栽试验,设置4年龄清水苜蓿根际土壤浸提液与水5种不同配比(1∶1、2∶1、3∶1、4∶1、5∶1)混合液作为处理,以浇灌等量水作为对照组(CK),探究不同浓度清水苜蓿土壤浸提液对连作马铃薯根际土壤环境酶活性和微生物群落的影响。结果表明,4∶1混合液处理的土壤过氧化氢酶活性、碱性磷酸酶活性较对照组提高10.14%、47.65%,厌氧型自生固氮菌、反硝化细菌的数量较对照组增加54.80%、36.78%,马铃薯产量较对照组提高10.52%;3∶1混合液处理的土壤脲酶和蔗糖酶活性比对照组提高51.70%、55.27%,细菌、放线菌和好氧型自生固氮菌数量比对照组增加7.77%、58.91%、47.57%,同时有效地降低了真菌的数量,比对照组降低12.42%;1∶1混合液处理的土壤过氧化氢酶活性仅低于4∶1混合液处理,好氧型自生固氮菌数量仅低于3∶1混合液处理;综合比较各项指标,2∶1和5∶1混合液处理的效果相对较差。不同浓度清水苜蓿土壤浸提液均可提高马铃薯根际土壤环境酶活性与部分微生物数量,降低真菌数量,进而有效改善根际土壤环境微生物群落结构,缓解马铃薯连作障碍,提高马铃薯产量;其中,4∶1混合液处理改善效果最佳。

In order to alleviate the continuous cropping obstacle of potato,a pot experiment was carried out with Xindaping potato as the test material.Five different ratios of 4-year-old Qingshui alfalfa(Medicago sativa L.)rhizosphere soil extracts and water mixed solution(1∶1,2∶1,3∶1,4∶1,5∶1)were set as treatments,and the control group(CK)was irrigated with the same amount of water.Effects of different concentrations of Qingshui alfalfa rhizosphere soil extracts on enzyme activities and microbial communities in continuous cropping potato rhizosphere soil environment was explored.The results showed that catalase and alkaline phosphatase activities in soil treated with the mixed solution(4∶1)were enhanced by 10.14%and 47.65%compared with CK.Compared with CK,number of anaerobic autogenic nitrogen-fixing bacteria and denitrifying bacteria increased by 54.80%and 36.78%and the potato yield was improved by 10.52%.Treated with mixed solution(3∶1),activities of urease and sucrase in soil were increased by 51.70%and 55.27%compared with CK.Compared with the CK,number of bacteria,actinomycetes and aerobic autogenic nitrogen-fixing bacteria were improved by 7.77%,58.91%and 47.57%.And the number of fungi was significantly reduced,12.42%lower than CK.Soil catalase activity of the mixed solution of 1∶1 was only lower than that of the mixed solution of 4∶1,and number of aerobic autogenic nitrogen-fixing bacteria was only lower than that of the mixed solution of 3∶1.Considering all these indicators,effect of treatment with mixed solution 2∶1 and 5∶1 were relatively poor.Different concentrations of Qingshui alfalfa soil extracts might increase enzyme activity and the number of some microorganisms,and reduce the number of fungi in potato rhizosphere soil environment.Thus,microbial community structure might be effectively ameliorated in the rhizosphere soil environment,thereby alleviating the continuous cropping obstacles of potato,and improving potato yield.Moreover,mixed solution with(4∶1)had the best effect.