关键词: 黄土高原北部, 紫花苜蓿, 人工草地, 群落演替, 植物多样性, 森林草原带

Abstract: Taking  60-day-old Pinus tabulaeformis seedlings as test objects, a pot culture experiment under laboratory condition was conducted to investigate whether the inoculation with Rhizopogon luteolus could infect P. tabulaeformis and form ectomycorrhiza as well as the effectiveness of this infection on the growth of P. tabulaeformis. After two months of inoculation, the ectomycorrhiza formed, and the mycorrhizal colonization rate was over 80%. In terms of branching characteristics, the binary ectomycorrhiza accounted for 80%, and the rod-shaped one shared 20%. The mantle was white in color, quite distinct, and 90 μm in thickness. The diameter of the ectomycorrhizal branch was 0.4-0.6 mm, and the length of the branch was 1.5-2.5 mm. The extraradical hyphae were white and villous, and many of them were twisted as rhizomorphae, with a length of 3.5-5.5 mm. The ectomycorrhiza had prominent promotion effect on the growth of P. tabulaeformis roots. The root-shoot ratio of the mycorrhizal seedlings was 2.7 times of the control. After the formation of
ectomycorrhiza, the phosphorus absorption by P. tabulaeformi from the environment increased significantly.

Key words: North Loess Plateau, Alfalfa (Medicago sativa), Artificial grassland, Community succession, Plant diversity, Forest-steppe ecotone