Correlation study on the diversity of the AM fungi and soil nutrients inthe rhizosphere of different kiwifruit cultivars

Abstract: 【Objective】The study was to explore the diversity and spatial distribution of arbuscular mycor⁃rhizal (AM) fungi, and the ecological function of soil nutrients in the rhizosphere of different kiwifruit culti⁃vars.【Methods】In July 2014, root and soil samples were collected from four cultivars of kiwifruit, includ⁃ing‘Hayward’(Actinidia deliciosa)[A. Chev.] C. F. Liang et A. R. Ferguson‘Hayward’),‘Hongyang’(A. chinensis Planch‘Hongyang’),‘Jinyan’(A. chinensis Planch‘Jinyan’) and‘Huangjinguo’(A. chinensis Planch‘Hort16A’). The soil samples were collected at three depths in the soil profile, i.e. 0-10, ＞10-20 and ＞20-40 cm. Root samples and rhizosphere soils were treated with alkali dissociation-acid fuchsinstaining method and wet-screened decanting-sucrose centrifugation. This study mainly determined therate of mycorrhizal infection and the spores density of AM fungi, identified AM fungi based on their mor⁃phological characteristics, and analyzed the infection characteristics, diversity of the AM fungi and its cor⁃relation with soil nutrients.【Results】Hyphae and vesicles were the main infection forms of AM fungi, butthe mycorrhizal infection rate was generally low with an infection level of 3. The highest infection rate wasin‘Hayward’, which was 34.3%; the lowest infection rate was in‘Huangjinguo’, which was 14.9%. 69species from 4 genera of AM fungi were isolated and identified in this study, 39 species belonging to Glo⁃mus, 24 to Acaulospora, 4 to Scutellospora, and 2 to Entrophospora. The two species of Entrophospora onlyappeared in the rhizosphere of‘Hongyang’and‘Jinyan’, and the other three genera were distributed inthe rhizosphere soils of the 4 cultivars. 9 dominant species were selected, namely Glomus liquidambaris,G. intraradices, G. claroideum, G. aggregatum, G. clarum, G. invermaium, Acaulospora rehmii, A. rugosaand Entrophospora colombiana. G. liquidambaris was the dominant species in the soil of the four cultivars.The spores of AM fungi were mainly distributed in the ＞10-20 cm soil layer, and the spore density of‘Hayward’at this soil layer was the highest (45.33/10 g soil), while the spore density of‘Huangjinguo’atthe 0-10 cm layer was the lowest (14.67/10 g soil). Spore density was significantly affected by the hostplants and soil depth. The distribution of species richness was similar to that of the spore density. The larg⁃est species richness of AM fungi was found in the ＞10-20 cm soil layer of‘Hayward’, which was 23.33;the smallest species richness of AM fungi was in the ＞20-40 cm soil layer of the‘Hayward’, which was8.33. The diversity index of AM fungi was the same as species richness. The highest diversity index wasfound in the ＞10-20 cm soil layer of‘Hayward’(H=2.92). The average diversity index of AM fungi atthe 0-20 cm soil layer was the highest. The highest content of total nitrogen was in the ＞10-40 cm soillayer of‘Huangjinguo’; the lowest was in the ＞10-20 cm soil layer of‘Hayward’. The highest content ofhydrolyzable nitrogen was in the 0-10 cm soil layer of‘Hongyang’while the lowest was in the ＞10-20cm soil layer of‘Jinyan’. The highest content of total phosphorus was in the ＞20-40 cm soil layer of‘Hayward’and the lowest was in the ＞20-40 cm soil layer of‘Jinyan’. The highest content of availablephosphorus was found in the ＞20-40 cm soil layer of‘Jinyan’while the lowest in the ＞10-20 cm soillayer of‘Hongyang’. The highest content of total potassium was 8 719.14 mg·kg^-1 and the lowest 3269.67 mg·kg^-1. The highest content of available potassium was 293.33 mg·kg^-1. The highest content of organic matter was 10.38% and the lowest was 3.78%. The pH values of soil samples ranged from 5.03 to6.68 and all of them were acid soil. The contents of total nitrogen, total potassium, available potassiumand organic matter were high in the rhizosphere soils of the four cultivars of kiwifruit, but the content ofavailable phosphorus was low. The correlation analysis showed that spore density had a significant positive correlations with soil layers and available phosphorus, and significantly negative correlations with total nitrogen and pH.【Conclusion】The roots of the 4 cultivars could be infected by AM fungi. The rhizo⁃sphere of different cultivars had rich resources of AM fungi. The species diversity of AM fungi had obvious spatial heterogeneity, and was closely related to the soil nutrient.