Study On The Effects Of Potato’s Different Intercropping Patterns On Soil Microorganisms Diversity

Potato was a superior crop in the Southern Mountainous Area of Ningxia. For limitation of land resources and the potato’s market demand, potato continuous cropping was widespread in the local area. The genetic diversity of soil microorganism was studied by using T-RFLP technique, ITS gene library, BOXAIR-PCR were used to detect the rhizosphere soil bacteria community characteristics and diversity of intercropping potato. Three intercropping cultivation models (intercropping of potato with maize, potato with fababean and intercropping of different potato cultivars) were researched to explore an effective intercropping cultivation model.Based on the ecological view, the study provided the theoretical basis to alleviate obstacles of potato continuous cropping and the results were as follows:(1)The total number of T-RFs of bacteria in rhizosphere soil of potato plants in all treatments was increased. The Shannon-Wiener index of bacteria in rhizosphere soil of intercropping potato was all higher than those of continuous cropping potato, and the highest index was demonstrated in the treatment of 4:1,3:2 (proportion of rows of potato and maize) among the intercropping potato and maize patterns and intercropping of three different potato cultivars.Potato rhizosphere soil bacteria community composition were distinctly improved by intercropping with the increased numbers of the phylum and class of rhizosphere soil bacteria. Oscillatoriophycideae, Deinococci, Chlorobia, Fusobacteriales, Nitrospira and Aquificae were found after intercropping. The highest class was demonstrated in the treatment of intercropping of potato with maize.The proportion of some genus of probiotics rised including Bacillus and Geobacillus and some new probiotics appeared such as Brevibacillus and Halobacillus, while the counts of pathogens decreased or even disappeared. The treatment of potato and maize intercropping could improve microenvironment of rhizospheric soil of potato plants and alleviate obstacles of potato continuous cropping.(2)The total number of operational taxonomic units (OTU) and Shannon-Wiener index of fungi in rhizosphere soil of potato plants were all lower than those of continuous cropping potato. The lowest Shannon-Wiener index was demonstrated in the treatment of 4:1,3:2 (proportion of rows of potato and maize) among the intercropping potato and maize patterns and the treatment of 4:1,3:2 (proportion of rows of potato and fababean) among the intercropping potato and fababean.Intercropping distinctly improved potato rhizosphere soil fungi community composition with the numbers of the phylum and class of rhizosphere soil fungi decreased significantly in the flowering period. Fungi inlvolved 17 class and 47 order were deteced by ITS gene library. Fungi inlvolved 12 class and 20 order were deteced by T-RFLP technology. Different dominant orders Glomerellales and Capnodiales were detected using the two methods respectively. The beneficial fungi including Glomerales and Diversisporales appeared after intercropping.(3)Cultivable actinomycetes diversity analysis showed that the bacterial diversity in rhizosphere soil of intercropping potato was all higher than those of continuous cropping potato using BOXAIR-PCR. UPGMA clustering results showed that the rhizosphere soil actinomycetes community composition in the treatment of 4:1 (proportion of rows of potato and maize) among the intercropping potato and maize patterns, the treatment of 3:2 (proportion of rows of potato and fababean) among the intercropping potato and fababean patterns and the intercropping of A and B potato cultivars had a bigger difference with that of continuous cropping.(4)To a certain extent, the treatment of 3:2 (proportion of rows of potato and maize) among the intercropping potato and maize patterns increased bacterial diversity, decreased fungal diversity and improved potato rhizosphere soil microbial community composition as well as stabilized community function. Thus, it was being an ideal cultivation pattern to alleviate obstacles of potato continuous cropping.