Responses of Castanopsis tribuloides and Pinus kesiya seedlings to mycelial inoculation of Russula alboareolata and Amanita princeps

Castanopsis tribuloides and Pinus kesiya are ectomycorrhizal (ECM) host plants. They are used for reforestation in degraded forestlands in northern Thailand. Objective of this research was to compare the effects of mycelial inoculation of Russula alboareolata and Amanita princeps, edible ECM mushrooms, on C. tribuloides and P. kesiya seedlings by evaluating ECM formation, growth response and nutrient accumulation. The study period was from 2018 to 2020. Two-month old seedlings of C. tribuloides and P. kesiya were inoculated with mycelium slurries of R. alboareolata and A. princeps. The effects of the ECM fungi on the host plants were evaluated at six months after inoculation. ECM roots of C. tribuloides associated with R. alboareolata and A. princeps were irregularly pinnate, whereas ECM roots of P. kesiya inoculated with the fungi were dichotomous branching patterns. Survivals of C. tribuloides seedlings in the uninoculated, R. alboareolata and A. princeps treatments were 66.7, 76.7 and 97.2% respectively. Survivals of P. kesiya seedlings in both the uninoculated and inoculated treatments were about 95%. Inoculation with the ECM fungi significantly increased the growth and nutrient accumulations of C. tribuloides and P. kesiya seedlings. The increase in dry weight was greater for inoculated plants of C. tribuloides than for those of P. kesiya. For C. tribuloides, the increase was significantly greater for plants inoculated with R. alboareolata than for those inoculated with A. princeps. For P. kesiya, there was no difference in the increase in dry weight between plants inoculated with each of the fungal species. Seedlings of C. tribuloides and P. kesiya associated with the edible ECM fungi may be beneficial for reforestation.