Studies On The Relationship Between Soil Microbial Community And Cultivation Environment In Apple Orchard

In the orchard ecosystem, effects of the soil microbial community are not neglectable. The management practices and yield in modern apple orchards affect the populations of soil microorganisms and soil environment. Since good plant growth environment in orchard ecosystem is one of the most important factors in apple production and the development of fruit industry, this study was to clarify the factors that influenced the orchard ecosystem, including the soil microbial community and the fruit tree management in the root system laboratory in College of Horticulture Science and Engineering, Shandong Agricultural University through investigating on growth of field and pot plants,"Fuji/ Malus hupehensis Rehd"apple trees and Malus hupehensis Rehd. seedlings, the ecosystem of the plant biology in different orchards were analysised. The influences of the organic fertilizer and the nitrogen and their combination on the Malus hupehensis Rehd seedlings , soil microorganism communities and the activity of the soil enzymes were measured. The results were as the followings:The relationships among soil nutrient content, rhizosphere microorganisms and activities of soil enzymes, which were regarded as a parameter to evaluate soil nutrient condition were analyzed to obtain the biological conditions of rhizosphere microorganism in 9 different apple orchards with varied yield. The results indicated that the above parameters were correlated with apple yield . The contents of alkali-N, olsen-P, and total-C increased with orchard yield increased. In high-yield-orchard, the populations of rhizosphere microorganisms and the activities of soil enzymes were high. There was a significant positive correlation between apple yield and species and the amount of the soil microorganisms, and that of the apple yield and olsen-P, avail-K, alkali-N and total-C, and the protease and phosphatase as well.This paper studied the changes of microorganisms and enzyme activities in"Fuji /Malus hupehensis Rehd"apple trees grown in pot media, and analyzed the relationships between the parameters. The results showed that the microorganisms community, enzymes'activities and diameters of apple trees were the lowest in the sands, while that of the highest in the loams and middle in clay. The change of the soil enzyme activity was greatest in the loams, while the least in the sands. The activities of the soil enzyme in the surface layer were higher significantly than that of in the deep layer. The changes in the composition of microorganisms communities were analyzed by PLFA , which showed that the characteristic fatty acid in fungi and G+ in the three different soil was the most in loams, and that was the least in sands. However, the characteristic fatty acid in G- and arbuscular mycorrhizal fungal﹙AM﹚ bacteria were the most in the clay, and those were the least in the sands. The AWCD value of the utilization of the carbon source determined by BIOLOG in the three different soils was the highest in the loam, and lowest in the sands, however, no significant difference was found between the loam and clay soils. It was indicated that soil biology change was consistent with the apple tree growth.Effects of nitrogen (N), organic fertilizer and their combination on the rhizosphere microorganisms and root growth of M. hupenensis Rehd. seedlings (2years old ) were investigated. The results showed that fertilizer application increased the numbers of rhizosphere microorganisms with the exception of nitrogen-fixing bacteria. Fertilizer N at the concentration of 500 mg kg-1 decreased the number of bacteria, actinomycetes and cellulolytic microbe, which reversed by applying the organic fertilizer at the concentration of both 3% and 6%. To alleviate the unfavorable effect of higher concentration N (500 mg kg-1), combination of 3% of organ fertilizer and 200 mg kg-1 N was the optimal choice. Numbers of bacteria, fungi, ammonifier bacteria and nitrobacteria were positively correlated with the biomass of growing roots and absorbing roots, while that of nitrogen-fixing bacteria was negatively correlated with absorbing root biomass. Correlation between number of cellulolytic microbe and root biomass was not detected. Only numbers of bacteria and cellulolytic microbe were positively correlated with root respiration rate of the M. hupenensis Rehd.seedlings. The amount of phosphor bacterium increased when N application at 200mg kg-1. And bacillus circulans had a high tolerance ability to N application.There was significant positive correlation between the amount of rhizosphere bacteria, fungis, aminate bacteria and dry weight of absorbing root. There was significant negative correlation between azotobacters and dry weight of absorbing root. And there was also significant positive correlation between the amount of bacteria and fibrin disassembling bacteria.Fertilizer application had dynamic influence on the activities of the soil enzyme. The application of nitrogen (N) and organic fertilizer increased significantly the enzyme activities in C, N, P cycling. The nitrogen at high concentration inhibited the activities of the soil enzymes. The activity of fibrin enzyme in C cycle changed greatly than that of cane sugar enzyme. Urease in N cycle was sensitive to fertilization. Enzyme activities in P cycling was in the following order: acid phosphatase>alkalescence phosphatase>neutral phosphatase. The species of soil microorganism was correlated with the activities of soil enzyme.Using BIOLOG method, the changes of microorganism diversity were studied. The application of organic fertilizer increased AWCD at the concentration of 200 mg·kg-1, while decreased at 500 and 700 mg·kg-1. Compared with CK, the diversities soil microorganism decreased significantly by applicating of nitrogen at high concentration , among which T1 is the highest, and T16 is the lowest. The effect of different fertilizers on carbon utilization was remarkable, indicating the changes of the microorganism community.Application of fertilizer changed FAMEs of rhizosphere microorganism community. Organic fertilizer and the nitrogen increased FAMEs. Application of the nitrogen at 200mg·kg-1 increased the content of FAMEs in bacteria, fungi, AMF and actinomycete, while decreased by applying nitrogen at high concentration. With the combination of the organic fertilizer and the nitrogen, the contents of biomarker fungi, AMF, G+ , FAMEs at 200 mg kg-1 of N were higher than those at 500 and 700 mg kg-1 of N.