Abstract: A pot experiment was conducted to study the effects of applying four kinds of Larix gmelini rhizosphere and bulk concentration root exudates from a Juglans mandshuricaL. gmelini mixed plantation on the root activity and mycorrhizal infection incidence of J. mandshurica. In the treatments of applying rhizosphere concentration root exudates, 2,4-2 hydroxy benzoic acid and ferulic acid improved the J. mandshurica root activity and mycorrhizal infection incidence by 33.5% and 10.7%, and 6.8% and 5.7%, respectively, while the other treatments decreased the root activity and mycorrhizal infection incidence, as compared with the control. In the treatments of applying bulk concentration root exudates, the J. mandshurica root activity and mycorrhizal infection incidence had a greater change, being increased or decreased, as compared with the control. Both the rhizosphere and the bulk concentration 2,4-2 hydroxy benzoic acid promoted the growth of J. mandshurica. The correlation analysis showed that there existed significant correlations between J. mandshurica root activity, mycorrhizal infection incidence, and biomass, with the correlation coefficients being 0.897, 0.91 and 0.877, and 0.912, 0.894 and 0.917, respectively, indicating that higher root activity and mycorrhizal infection incidence promoted the growth of J. mandshurica.

Key words: winter wheat, maize straw, C, rotation, decomposition., N, P, K