菌根真菌多样性对西南亚高山针叶树种云杉幼苗生长及养分吸收机制的影响

Based on the influence of mycorrhizal fungal diversity in maintaining the diversity of forest ecosystem, contrapose forests are difficult to renew in subalpine coniferous forest of southwestern China due to single species of forests, this program will combine field investigation and Picea asperata seedling indoor-grown, Picea asperata seedlings inoculated with four different gradients of species communities of ectomycorrhizal fungi simultaneously and without mycorrhizas in axenic culture. (1) Mycorrhizal infection rates of roots, mycorrhizal root tips enzymes activity, and the absorption rates of nutrients for mycorrhizal roots and non-mycorrhizal roots will be monitored regularly for each treatment. (2) Combine with determination of the growth parameters, nitrogen, phosphorus contents of roots and stems as well as the underground and aboveground biomass, and also phosphorus, nitrate, ammonium and mineralization rate of soils for each treatment. (3) Compare the differences in contribution rate of mycorrhizal roots enzymes activity to soil enzymes activity and absorption rates of nutrients for mycorrhizal roots and non-mycorrhizal roots among different treatments. Thereby the relationship between growth characteristics of Picea asperata seedlings and mycorrhizal fungal diversity will be established through mycorrhizal root tips enzyme activity and absorption rates of nutrients for mycorrhizal roots. Then the influence of mycorrhizal fungal diversity on Picea asperata seedling growth and mechanism of nutrients uptake will be furtherly explained. The program will be expected to provide a theoretical basis for the reconstruction and restoration of southwest subalpine artificial coniferous forest, and also provide references for forward selection of mycorrhizal fungal type which can be applied in forest restoration in the future.

摘要:基于菌根真菌多样性在维持生态系统多样性中的影响力，针对西南亚高山人工针叶林由于物种单一使得森林难以更新等问题，本项目将结合野外调查实践与云杉幼苗室内培养，采用五种梯度多样性的菌根真菌接种的方法，定期监测（1）每种处理的菌根侵染率、菌根酶活性、菌根对营养离子流的吸收速率等指标；（2）同时结合云杉幼苗根茎生长参数、氮磷含量、地下和地上部分生物量，以及土壤磷、硝态氮、铵态氮等养分元素含量、矿化速率等参数的测定；（3）对比分析不同处理的菌根真菌酶活性对土壤酶活性的贡献率的差异，以及菌根对营养离子流吸收速率的差异，通过菌根酶活性和菌根对营养离子的吸收率两种途径建立起云杉幼苗生长特性与菌根多样性之间的相互关联性，进而深入阐述地下菌根真菌多样性对云杉幼苗生长发育及其对土壤养分吸收机制的影响。为西南亚高山人工针叶林的重建和恢复提供理论基础以及未来可应用到森林恢复中的菌根真菌种类的预选提供参考依据。

关于菌根真菌多样性的研究，多数都还集中于对其影响因子的研究，极少数研究聚焦于单个菌根真菌接种对宿主生长的影响，但对于不同梯度多样性的菌根真菌群落对植物生长的影响及机制的研究还很缺乏。本项目通过接种五种不同梯度多样性的外生菌根真菌群落于云杉幼苗，定期监测土壤物理生化性质、菌根真菌侵染率、与碳氮磷转化相关的土壤酶及菌根真菌酶活性、幼苗生长特征参数。结果表明不同处理土壤和根系亮氨酸氨基肽酶和酸性磷酸酶活性的差异主要受外生菌根多样性的驱动。根系β-葡萄糖苷酶、β-葡萄糖苷酶和酸性磷酸酶活性分别与土壤β-葡萄糖苷酶、β-葡萄糖醛酸酶和酸性磷酸酶活性显著相关。在碳代谢相关途径方面，外生菌根多样性主要通过增加根系和土壤总酶活性(β-葡萄糖苷酶、β-葡萄糖醛酸酶、过氧化物酶和酚氧化酶)来影响生物量的生长速率。在氮代谢途径上，土壤和全根系统中降解含氮化合物的酶(亮氨酸氨基肽酶和N-乙酰-β-D-氨基葡糖苷酶)以及植物总氮含量的变化是导致生物量增长速度加快的主要原因。总体表明植物外生菌根真菌群落的多样性通过物种间的功能互补促进了幼苗的潜在酶活性，进而促进了幼苗的生长。因此，我们的研究结果有助于更好地建立植物生长和外生菌根真菌多样性之间的机制联系，并可将其整合到森林生态系统中，以提高我们对碳 (C) 固存和土壤养分循环的理解。