The Study Of Arbuscular Mycorrizal Resources In The Rhizosphere Of Fengjie Navel Orange (Citrus Sinensis Osbeck)

The mycorrhiza is a symbiont with fungus and root. Arbuscular Mycorrhiza( AM) is famous for the cauliflower shape structure named "arbuscule" in the cortex cells of roots. The AM fungus widely exists in the nature, about 90% land plants lived in the world can form the symbiont. AM fungus can improve the ability of plant to take up water and the nutrient. So, the abilities of the plant uptaking water from soil and withstanding aridity and arid are improved. The plant growth is stimulated. Plant production and quality are improved. AM fungus ecology compatible, except massively distributes in agricultural and the forest soil, the desert, the coral reef, the coastal shallow seas and tidelands, the salina, the barren soil and some industry pollution areas, in the waste mining area soil, the corroded soil all has the distribution. In recent years, AM fungus's resources investigation and the ecology research in the adverse circumstance are more and more valued by people.The Arbuscular fungus had formed the symbiont with the ancient land lower plants before the appearance of the higher plant. AM fungi lived with the land plants and evolved and developed together which played a vital role in the land plant evolution. They are maintaining continuously symbiosis life style with the apparatus of the plant root. The soil is not suitable for the plant growth when the plants moved from aquatic environment to the land. But those plants with the mycorrhizal fungus symbiosis can survive in the rock matrix or the slit. Thus the role of AM fungi palyed may be more bigger in the immature soil development habitat. The species richness of AM fungi is also bigger than that of in the mature soil.At present the resources investigation of arbuscular mycorrihzal fungi in China involves these special habitats of the salina , the delta, the river valley as well as the islands scattered in 19 provinces and cities. But the AM fungus resources investigation in Three Gorges Reservoir Area until is not reported yet now; Generally speaking, new species or new record species of AM fungus may be discoved in a new habitat where has not been investigated yet. Fengjie County is situated at the east of the southwest China, the Yangtze River middle and reaches Three Gorges Reservoir Area district intimate region. Its geological construction shape mark mainly is drape. The stratum all is the sedimetary rock, from the Silurian to the quaternary system, and all the mountins appear except the mountins of the tertiary and the Cretaceous. The carbonate rocks class approximately composes 50.4% of the county-wide breadth area, the broken stone rocks class accounts for 49.6%. So many kind of the soil within the boundaries is regosol (carbonate rocks and purple rocks). The growth of agriculture soil is not deep.