土荆芥不同发育期根际土壤养分、酶活及微生物数量的变化

Changes of Soil Nutrient, Soil Enzymes Activities and Microbial Communities in Rhizosphere Soil of Chenopodium Ambrosioides L. at Different Development Phases

采用盆栽试验,通过比较土荆芥营养期和果期根际土壤中养分、土壤酶活和微生物数量的变化规律,明确土荆芥入侵对土壤生态系统的影响效应,为进一步了解土荆芥入侵机理和制定防控措施提供理论依据。结果表明:(1)土荆芥入侵对土壤养分具有一定的影响。与对照相比,除了土荆芥营养期根际土壤总钾的含量增加了12.26%外,所测其它土壤养分指标均不同程度下降。其中,果期总钾含量降低3.27%,营养期和果期的有机质含量分别降低20.41%和1.22%、总氮含量分别降低27.87%和16.39%、总磷含量分别降低29.41%和14.71%、速效磷含量分别降低49.24%和34.69%、速效钾含量分别降低76.65%和57.22%;(2)土荆芥的生长对土壤胞外酶具有一定的影响。与对照相比,营养期和果期土壤硝酸还原酶活性显著升高(P<0.05),分别升高了87.23%和137.23%;营养期的脲酶活性降低了45.92%,与对照差异显著(P<0.05);营养期和果期根际土壤的蔗糖酶、酸性磷酸酶、过氧化氢酶活性的变化均未达到显著程度(P>0.05);(3)土壤微生物数量随着土荆芥生长而增加,但只有真菌数量与对照的差异达到显著水平(P<0.05),营养期和果期真菌数量分别增加32.11%和86.18%;(4)与果期相比,营养期土壤养分含量、土壤酶活性和微生物数量普遍较低,推测土荆芥生长初期通过降低土壤营养水平,抑制其周围对营养水平要求较高的植物生长,以获得竞争优势,而果期则通过释放根系分泌物增加了土壤微生物数量和土壤酶活,使土壤养分回升,从而为其繁殖提供有利条件。

A pot experiment was used to study the effects of Chenopodium ambrosioides L. on soil ecosystem, through the variationsof soil nutrient, soil extracellular enzymes activities and microbial communities in rhizosphere soil at its nutrient phase and fruitingstage. The results may help us further understand the invasion mechanism of C. ambrosioides and provide theoretical basis for theprevention and control measures. The results showed that：（1） The invasion of C. ambrosioides had certain effects on soil nutrients.Compared with the control group, except that the content of total K in rhizosphere soil of C. ambrosioides at nutrient phase wasincreased by 12.26%, the other soil nutrient indexes were decreased in varying degrees. Of which, the content of total K weredecreased 3.27% at fruit phase; total organic matter at nutrient phase and fruit phase were decreased by 20.41% and 1.22%,respectively; total nitrogen at nutrient phase and fruit phase were decreased by 27.87% and 16.39%, respectively; total P at nutrientphase and fruit phase were decreased by 29.41% and 14.71%, respectively; available P at nutrient phase and fruit phase weredecreased by 49.24% and 34.69%, respectively; available K at nutrient phase and fruit phase were decreased by 76.65% and 57.22%,respectively; （2）The invasion of C. ambrosioides also had influences on the soil extracellular enzymes. Compared with the controlgroup, the activity of soil nitrate reductase at nutrient phase and fruit phase had a significant increase （P〈0.05） that were increased by87.23% and 137.23% respectively; Urease activity at nutrient phase reduced by 45.92% compared with the control group, which wasa dramatic drop （P〈0.05）; The variations of activities of invertase, acid phosphatase and catalase in rhizosphere soil at nutrient phaseand fruit phase did not have obvious differences （P〉0.05）; （3） The soil microbial population was increasing along with the growth ofC. ambrosioides, but only the amount of fungi had significant difference with the control group （P〈0.05）. The amount of fungi atnutrient phase and fruit phase increased by 32.11% and 86.18% respectively; （4） Soil nutrient content, soil enzyme activity and themicrobial population at nutrient phase were generally lower compared with the fruit phase. We speculated that at the early growthstage of C .ambrosioides, it inhibited the growth of surrounding plants which needs higher nutrition by reducing the soil nutrient, toimprove its competitive advantage. Later at the fruit phase, the root exudates of C. ambrosioides may release into the soil to enhancethe amount of soil microbe and activities of soil enzyme, which caused the recovery of rhizosphere soil nutrient and thereforeprovided favorable conditions for its breeding.