| Based on the low survival rate and slow seedling growth of afforestation in poor nutrition soil in Shangnan County of Shaanxi Province, using mycorrhizal biotechnology, the four plants, which named Pinus tabulaeformis, Cunninghamia lanceolata, chaenomeles speciosa and Eucommia ulmoides respectively, was inoculated with arbuscular mycorrhizal and ectomycorrhizal fungi for afforestation in situ in the wild mountains. The effects of mycorrhizal on physiological and biochemical substances and resistance in the seedling was determined. And the impact of mycorrhizal on the survival rate of afforestation and forestation seedling growth was also researched. The main conclusions are as follows:1 Three kinds of ectomycorrhizal fungi, named Suillus bovines, Suillus luteus, Boletusl luridus, strongly infected Pinus tabulaeformis, Cunninghamia lanceolata. Comparing with the control plant, mycorrhizal plant significantly improved the survival rate above 9% and 24%, promoted seedling height 4.85 cm, 0.68 cm, and caliper 0.99 mm, 0.60 mm of seedlings of Cunninghamia lanceolata and Pinus tabulaeformis, repectively. It also changed physiological and biochemical material content in the seedling. The mycorrhizal colonization had increased 0.42 mg/g, 0.32 mg/g and 0.09mg/g, 5.23mg/g of tree proline and chlorophyll content of seedling of Cunninghamia lanceolata and Pinus tabulaeformis, repectively. However, it lowered the seedlings membrane lipiding peroxidation about 0.083mmol/g, 0.005mmol/g for the two kinds of plants. Therefore the mycorrhizal seedlings improved the ability to live in adverse environmental resilience. The seedlings inoculated Suillus bovines, Boletus luridus for afforestation were more effective than the seedlings inoculate Suillus luteus.(2) And the effect of reforestation was better in sunny shadow slope than slope. The seedling height and caliper were 0.95 mm and 4.64 cm higher in sunny slope than in shadow slope for Cunninghamia lanceolata. And the mycorrhizal infection and free proline content were 12.84% and 1.79 mg/g higher in sunny slope than in shadow slope for Pinus tabulaeformis. The seelings grew better in second year than in the first year. The mycorrhizal infection, chlorophyll and free proline content were 15%, 0.33 mg/g, 4.47 mg/g higher in second year than in the first year for Cunninghamia lanceolata. However, the caliper chlorophyll and free proline content were 0.12 mm, 0.10 mg/g, 6.16 mg/g higher in second year than in the first year for Pinus tabulaeformis. (3) The chaenomeles speciosa and Eucommia ulmoides seedings was inoculated with the arbuscular mycorrhizal fungi coming from chaenomeles speciosa rhizosphere soil separation. The fungi had strong ability to infection on two host plant. The infection rate was 95% and 99% respectively. And the mycorrhizal seedlings increased the survival rate 25% and 31%, promoted seedling height 5.19cm, 6.75 cm and caliper 0.67 mm, 0.61 mm with chaenomeles speciosa, Eucommia ulmoides respectively. It also increased 67.52 mg/g, 56.8 mg/g of chlorophyll content, lowered 10.43 mmol/g, 2.01 mmol/g of membrane lipiding peroxidation in the seedlings of the two plants. Therefore the mycorrhizal seedlings improved the ability to against adverse environmental resilience.The results showed that mycorrhizal colonization was able to greatly improve the survival rate of afforestation, promotion of seedling growth, enhance seedling resistance. So it was a new alternative afforestation technology.
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