Effects of Nitrogen Application Rates on Rhizosphere Microbial Community Functional Diversity in Maize and Potato Intercropping

Abstract

Field trials were carried out to investigate the effects of different nitrogen application rates N0(0 kg·hm-2), N1(125 kg·hm-2), N2(250 kg·hm-2)and N3(375 kg·hm-2)on the rhizosphere microbial population and metabolic function diversity of maize and potato under intercropping using plate culture method and BIOLOG technique. The results indicated that nitrogen(N1, N2 and N3) application in-creased the amounts of bacteria, actinomyces and total microbes, but decreased the quantities of fungi significantly in rhizosphere soil of maize and potato in intercropping, and the highest increment was with N2 treatment. In comparison with N0, nitrogen fertilizer application could increase significantly the diversities of soil microbial community, the utilization rate of carbon source, richness of soil microbial community. And the AWCD value, Shannon-Wiener index(H), Simpson index(D), Evenness index(E)and Richness index(S)in rhizosphere soil of maize under intercropping were the highest at N3 treatment, while that of potato were the highest at N2 treatment, but the effects of different N application rates on the ability of rhizospheric microbes in utilizing six types of carbon sources were different. Principal component analysis(PCA)and cluster analysis showed that there were differences in carbon substrate utilization patterns and metabolic characteristics of the soil microbes in maize and potato intercropping with different N application rates. It suggested that applying N could regulate the rhizosphere soil microbial communities and promote the functional diversity of crop intercropping.