Preliminary Investigation On The Community Structure And Function Of Arbuscular Mycorrhizal Fungi In The Soil Of Commercial Greenhouse

As an important environmental and functional fungi, arbuscular mycorrhizal (AM) fungi widely distribute in terrestrial ecosystems. They make great contributions in sustainable agriculture and forestry, and play a vital role in maintaining and enhancing biological diversity, and ecosystem productivity. Under natural conditions, AM fungi play various of physiological, biochemical and ecological roles directly and indirectly according to its unique community structure and function. AM fungi have huge potential for both soil bioremediation and biological control of soil borne diseases. Soil is a heterogeneous system including many microorganism strains, so it is more significant to study the composition effectiveness of multiple strains from the perspective of community. However, we know little about AM fungal community structure and Physiological functions in commercial greenhouse at present. In this paper, the community structure of arbuscular mycorrhizal fungi in commercial greenhouse soil at three locations in China (Daxing in Beijing, Changle and Laiyang in Shandong) was investigated using both morphological identification and denaturing gradient gel electrophoresis. Based on AM fungal community structure analysis in farmland soil, we designed different AM fungal community composition. The contribution to plant health, the soil quality, the ecosystems productivity in protected cultivation field caused by AM fungal community was examined.as few studies were carried out to determine the effects of AM fungal community on plant growth and soil quality. It will be helpful for providing an important theoretical basis and reference value for the environmental restoration and exploitation and application of AM fungal agents with high efficiency in the soil of commercial greenhouse. The main results showed that:1. Horizontal structure showed that: Glomus was a dominant genus in the sampling sites, G.etunicatum was the dominant species in 5-year replanting soil of Daxing and Changle, G.claroideum was the dominant species in 5-year and 10-year replanting soil of Changle and Laiyang, A.lacunosa was the dominant species in 10-year replanting soil of Daxing, the dominant species in 15-year and 20-year replanting soil was not obvious. G.claroideum was present in replanting soil at all sites. The Sorenson's similarity coefficients of AM fungal community composition ranged from 0.67 to 0.84 in 5-year replanting soil, and 0.29 to 0.33 in 10-year replanting soil. Vertical structure showed that: the spore abundance, species richness and Shannon index were highest in the topsoils (0-10 cm), and decreased with soil depth in all soils investigated. Time structure showed that: the spore density, species richness and Shannon index were greatest in June and October. Species richness and Shannon index were lower in August and December.2. PCR-DGGE analytical results suggested that Shannon indice was first declined and then tending to mitigate. Species richness and Shannon index were lower in the soil of commercial greenhouse, species richness decreased with the increasing of replanting years The canonical correspondence analysis (CCA) showed that the two first axes, indicators of closely relationship between the soil properties and AM fungal community, explained 67.6% of the total variance. Available P and replanting years were main factors contributing to the variance of the AM fungal community composition.3 The greenhouse experiments showed that water-stable aggregate fractions in 2-5,1-2,1-0.5 and 0.5-0.25 mm were generally improved in the tested degraded soil when treated with AM fungal communities, and soil salt ion concentration and soil EC were decreased as well. No significant changes were found in soil pH. Inoculation with AM fungal communities increased the number of bacteria and actinomycetes, but reduced the number of fungi. AM fungal communities apparently increased plant growth and dry mass, the soluble sugar content, Chlorophyll content and root activity of cucumber plants when compared to non-mycorrhizal or single-inoculation treatments. Among all inoculation treatments, AM fungal community F (Glomus etunicatum + G. mosseae + Gigaspora margarita + Acaulospora lacunose) and AM fungal community G (G. aggregatum + G. etunicatum + G. mosseae + G. versiforme + Gi. margarita+A. lacunose) showed greater contribution to the improvement of soil quality and plant growth, indicating that inoculation with AM fungal community had more beneficial effects than with single or double species.We studyed the community structure and function of arbuscular mycorrhizal fungi in the soil of commercial greenhouse at home and abroad for the first time, proved that AM fungal community had a function of soil bioremediation. This paper provided an important theoretical basis and reference value for the exploitation and application of AM fungal agents in the soil of commercial greenhouse.