Study On Soil Microbial Community Characteristics Different Plant Age The Apple Tree

The characteristics of soil microbial community are closely related to the plant growth. For the particularity of the climate and soil, apple planting is becoming an important part of industrial structure of agriculture in the Loess Plateau region. It has important directive significance to research on the characteristics of soil microbial community of the apple tree on the area and to study the relationship among the soil environment, fruit growth and soil microbial community.The place of the research is in the fuji apple orchard in Yichuan County in Shaanxi Province. The different plant age (3a,7a,10a,12a,17a and20a) of apple trees are selected to be as research objects. It adopts the method of microorganism cultivation, chloroform fumigation extraction analysis, DGGE, soil enzymes and soil nutrient analysis combined with multivariate mathematical statistical analysis to study the Spatial-Temporal feature of soil microbial community, soil nutrient composition and the effects on the soil microbial community structure of apple tree leaffall and root tissues. It also focuses on the correlation among different numbers of indicators. The main results are as follows:1. Properties of microorganism community.(1) Microorganisms of the three major groups and the major physiological groups both have significant rhizosphere effect. Along with the increase in plant age, the number of rhizosphere bacteria first increased and then decreased. Except the number of nitrification bacteria and cellulose decomposing bacteria decreased from17a to20a, the number of rhizosphere ammonification bacteria, nitrogen-fixing bacteria, nitrosated bacteria and cellulose decomposing bacteria first decreased and then increased.(2) Except the20a, all the other plant age rhizosphere bacteria DGGE bands are larger than the root outside, rhizosphere effect is significant. Along with the increase in plant age, the rhizosphere bacteria DGGE bands are showing a decrease-increase-decrease trend.(3) The MBC content are higher in the rhizosphere than root outside, rhizosphere effect is significant. Except the MBC content increased from17a to20a, along with the increase in plant age, rhizosphere MBC first increased and then decreased.(4) Catalase, invertase, urease and cellulase enzyme activities of rhizosphere are higher than that of the root outside, rhizosphere effect is significant, as alkaline phosphatase was contrary. Along with the increase in plant age, rhizosphere soil enzyme activity first increased and then decreased, except that invertase, alkaline phosphatase and cellulose increased from17a to20a. What’s more, the urease has greater volatility.(5) No significant rhizosphere effect on soil nutrient. Along with the increase in plant age, available P content of rhizosphere is gradually declining while pH value is gradually rising, alkali solution N is showing a decrease-increase-decrease-increase trend. Other such as organic matter, total N, total K, available K, total P are showing a first increased and then decreased trend.2. According to PCA result that has microbial composition, moil enzymes, moil nutrient as variables, fruit trees of different planting age are sorted into four classes, which are A (3a), B (7a), C (10a-12a) and (17a-20a). They represent different apple growth stages respectively:3a means fruiting early stage,7a means fruiting initial stage,10a-12a means fruiting prosperous stage,17a-20a means fruiting late stage.3. There is an extensive correlation among the soil microorganism, soil nutrient and enzyme activity. For example, there is a significant positive correlation among soil organic matter, total N, total K, available K, total P, pH value, invertase, cellulase, fungal and ammonification bacteria.4. Leaffall, root and prepared mixture of the two extracts of different plant age of apple trees are used to deal with the outside root soil of3a fruit trees separately. After that, it showed that the total number of microbes increased, especially the number of bacteria and fungi increased largely;10a and12a fruit trees components have greater effect.It shows that the apple characteristics of soil microbial community have significant rhizosphere effect. What’s more, with the growth of fruit trees, it shows different variation. According to the change of multiple soil environmental factors, the apple growth stages can be divided into fruiting early stage, fruiting initial stage, fruiting prosperous stage and fruiting late stage. It may be benefit for prolonging the apple’s fruiting prosperous stage by taking measures of changing the soil microbial composition, soil enzyme activity or soil nutrient content. That the apple trees’own composition returns to the soil can improve the structure of soil microbial community and the level of biomass. Trying to use the litter of apple tree to change the microbial community composition can may be enhance the apple production in the cultivation and management of apple tree.