The Investigation of AMF on the Resistance of Betula alnoides Stem Rot

Betula alnoides is the most south species of Betulaceae. There are more than 8.0104hm2 of B. alnoides plantation in Dehong, Yunnan province. However, due to large areas of monoculture B. alnoides plantation, the stem rot of B. alnoides is becoming more and more serious. Three plots of B. alnoides plantations in Yingjiang County, Dehong, were selected as the sampling plots. The investigation was carried out by wet sieve precipitation method, AM colonization examination and disease incidence survey in three plots with different disease levels of B. alnoides stem rot of three piece. The AMF spore density, AM colonization rate, the disease rate and the disease index were determined. The statistics analysis was carried out by SPSS 11.5. Results showed that when AMF spore density and AM colonization rate is higher than 40.08 spores/g and 77.5%,the stem rot of B. alnoides incidence of disease and disease index were 12% and 3.When the AMF spore density and the AM colonization rate were below the 1.05 spores/g and 13%, the stem rot of B. alnoides incidence of disease and disease index were 100% and 80,respectively. Through correlation analysis, there was significant negative correlation (P0.01) between the AMF spore Shannon-Wiener diversity index and Margalef abundance index and the incidence of B.alnoides stem rot.Therefore, it can be concluded that there is significant relationship between the number and diversity of AMF in forest land and the stem rot of B. alnoides. AMF can effectively reduce the incidence of B. alnoides stem rot. It is suggested that adding AMF spore into the seedling container of B. alnoides may increase the resistance to B. alnoides stem rot.