| The northern piedmont of Mt. Qinling is the largest kiwifruit production base in the world. The long term relatively monoculture of kiwifruit resulted in differences of soil microbial ecology in orchards with different planting years. It could provide fundamental basis for the scientific management of kiwifruit orchards via the study on the functional diversities of soil microbial community in kiwifruit orchards of different planting years. The soil samples were collected from kiwifruit orchards of different planting years, the quantities, populations and functional diversities of the soil microorganisms were then studied by the plate counting method and Biolog-Eco micro-plate method, finally the pertinence analysis was carried out between the microbial functional diversities and soil nutrients. The results showed that the cultured microbes from the orchard soils mainly were bacteria, followed by actinomycetes, and fungi the least. With the increment of planting years, the numbers of bacteria and actinomycetes decreased significantly, while the number of fungi increased obviously. The average well color development (AWCD), Shannon-Wiener index (H′), Simpson index (D), and Mclntosh index (U) of soil microbial community were all decreased significantly with the increment of planting years of kiwifruit orchards. The principal components analysis showed that the utilization characteristics of the carbon sources varied significantly among the kiwifruit orchards with different planting years. And these orchards with different planting years (0-5 a, 5-10 a, and 10-20 a) were divided into the first, fourth and third quadrant of the load diagram respectively. The utilization rates of soil microorganisms for sugars, amino acids and esters were higher than that for alcohols, amines and acids. There were 11 carbon sources contributed significantly to the first principal component (|r|≥0.5), among them 36% were sugars and 18% were amino acids and esters. The pertinence analysis of soil microbial functional diversities and soil nutrients showed that the soil microbial functional diversities positively correlated with soil organic matter, and negatively correlated with available phosphorus and quick acting potassium. The quantity and structure of soil microbes changed with the increment of the kiwifruit orchards planting years, meanwhile, the microbial functional diversities and the carbon utilization capacity decreased with the increase of the kiwifruit orchards planting years. Considering the pertinence between soil microbial functional diversities and soil nutrients, it is necessary reasonably to increase organic fertilizer and properly decrease the application of available phosphorus and quick acting potassium fertilizer. |
