Study On Root Microorganism And Soil Enzyme Of Two Typical Water Spinach With Low And High Shoot Cadmium Accumulation

Screening varieties of low capacity to accumulate heavy metals in particular vegetables, to grow vegetables in line with food safety requirements in the heavy-metal contaminated soil is the question which urgent needs to solve.This article take already screened water spinach Cd low accumulation variety QK and Cd high accumulation variety T-308 obtains as the object of study.Through the root box experiment,planting the first and second crops in the control soil(Cd concentration of 0.173 mg·kg^-1)and moderate Cd contaminated(Cd concentration of 0.726 mg·kg^-1)of farmland soil.Isolated from the rhizosphere different levels of distance(rhizosphere is S1,approaches rhizosphere is S2,far away from rhizosphere is S3)three soil micro-regions discussed the characteristic on root system microorganism (bacteria,fungus,actinomycetes)and the soil enzyme(urease,invertase,phosphatase)of two typical cultivars with low and high shoot Cd accumulation of water spinach.The main results were as follows:(1)The characteristic of Cd accumulation of water spinach has the stability.In the different soil,Cd concentration in shoot and leaf of QK was significantly(p＜0.01) lower than that of the T-308.And in the different crop,this difference of Cd concentration in shoot and leaf in varieties has the same result.(2)The microbes in the inter-species are very significant(p＜0.01)the difference.The number of microorganism in the T-308 is higher than that in the QK in two crops. But the root microorganism in two crops difference performance is different,in the first crop, bacteria is the most significant difference in the variety,fungus next,actinomycetes third,but in the second crop,actinomycetes is first bacteria second,fungus third.In addition, microorganisms in the difference between the species as the horizontal distance from the rhizosphere increase decreases(that is,rhizosphere S1＞S2＞S3).(3)The root system microorganism has the remarkable difference to two typical variety stem leaf Cd content influence. The root system microorganism takes the inhibitory action to QK,but takes the promoter action to T-308.And their influence function to QK was greater than that to T-308.The change relation between Cd concentration in shoot and leaf of QK and the root system fungus is closest,but variety T-308 and the root system bacterium is closest.(4)The activity of soil enzyme between the species was significant(p＜0.01)the difference.In the first crop,the T-308 soil enzyme activity is extremely remarkable bigger than QK the activeness in the contaminated soil,but compares on the control to display opposite,but in the second crop,the QK soil enzyme activity is bigger than that of T-308.Approaches the rhizosphere the S2 enzyme activity is biggest in variety difference,the rhizosphere S1 next, far away from rhizosphere S3 third.(5)The root soil enzyme activity has the remarkable difference to two typical variety stem leaf Cd content influence.The root soil enzyme activity takes the promoter action to QK,but takes the inhibitory action to T-308.And their influence function to the T-308 was greater than that to the QK.The change relation between Cd concentration in shoot and leaf of QK and the invertase is closest, but T-308 and phosphatase is closest.