入侵植物紫茉莉根系分泌物对土壤微生态环境的影响

水培紫茉莉幼苗收集根系分泌物,用3种不同浓度的根系分泌物(低浓度LC,中浓度MC,高浓度HC)处理麦田土,测定其对土壤养分含量、酶活性和微生物群落的影响.结果表明,紫茉莉根系分泌物降低了土壤碱解N、有效P和K的含量,在高浓度处理下分别下降37.10%、46.71%和23.85%,达显著水平,而土壤有机质含量显著提高,增加了43.25%;土壤尿酶、碱性磷酸酶和纤维素酶活性均呈下降趋势,在中浓度处理下已达显著水平,而蛋白酶活性与此相反;随着根系分泌物浓度的提高,土壤细菌和放线菌数量表现出降—升—降的变化趋势,而土壤真菌则先升后降.紫茉莉根系分泌物改变了土壤微生物群落结构和土壤养分的供求平衡,实现自身生物量快速增长,提高竞争能力,从而实现成功入侵.

Effects of Root Exudates from Mirabilis Jalapa on Soil Microenvironment

Mirabilis jalapa seedlings were cultured in hydroponics,root exudates(RE)were collected by concentrating the deionized water,in which the M.jalapa seedlings transferring to.Collected root exudates were subjected to the soil with winter wheat cultivation.Soil available nutrition contents,enzyme activities and microorganism population were determined. The results showed that the root exudates of M.jalapa could significantly reduce the contents of the alkali-hydrolyzable N,available P and K in soil under the high input,respectively decreased by 37.1%,46.71%and 23.85% But high input of M.jalapa root exudates significantly improved(P<0.05)the organic matter in soil,increased by 43.25%.The exudates could reduce the soil enzyme activities except for protease,and which was declining along with the raising input.The difference was significant when the input of root exudates was middle level.But high input of M.jalapa root exudates significantly enhanced(P<0.05)the activity of protease in soil.The amount of bacteria and actinomycetes in treatment LC and HC showed an evident reduction in the population of living microorganisms.However,the population of fungi increased under treatment LC and MC,which was almost twice as much as that in corresponding control when the root exudates was middle concentration.But the fungi population in treatment HC was significantly lower than in corresponding control Conclusively,the root exudates of M.jalapa imposed a prominent influence on soil micro-ecology environment in wheat field.