Two-year-old Scots pine (Pinus sylvstris var.mongolica) seedlings were treated with Pt mycorrhiza powder, ABT root-growing powder, HRC water-absorbing agent and high-yield powder, and planted on the sandy land in Balinyouqi, Inner Mongolia (180°12′13″E and 43°13′05″N). The effect and function of these biological agents on survival rate of seedlings were tested and analyzed by measuring the fine root growth and gross root growth. The results showed that the survival rates of the seedlings treated with Pt3, ABT, and HRC biological agents increased by 29.3%, 23.6%, and 16%, respectively. The regression analysis revealed that the length of fine roots (<2 mm) was positively correlated with seedling survival rate, which means that the Pt3 powder, ABT foot-growing powder and HRC water-absorbing powder increased the survival rates of the seedlings by promoting the growth of fine roots. Keywords Biological agents - Pinus sylvstris var.mongolica - Sandy soil - Roots - Survival rate CLC number S723.1 - S791.253 Document code A Foundation item: This article was supported by the National Natural Science Foundation of China (No. 39970627).Biography: TANG Feng-de (1967-), male, Ph. Doctor in Institute of Applied Ecology. Chinese Academy of Sciences, Shenyang 110016, P. R. China.Responsible editor: Zhu Hong
