Abstract

Sunlayanuban, P. (1991)

Effects of Mycorrhizae on Germination and Seedling Growth Rate of Native Tree Species.

Previous attempts to germinate the seeds of native trees often resulted in low germination rate or slow rate of seedling growth. In this experiment the hypothesis that this was caused by lack of infection of the seed or seedling roots by mycorrhizal fungi was investigated. Mature seeds from 13 tree species in Doi Suthep-Pui National Park were collected, together with soil containing rootlets of the adult tree, and any mycorrhizae present. Half the soil was sterilized by autoclaving to kill mycorrhizae. The germination rate and seedling growth rate were compared between seeds sown in sterilized soil and those sown in non-sterilized soil. Only five species germinated i.e. Nyssa javanica, Sapindus rarak, Spondias axilaris, Antidesma bunius and Sapium baccatum. Only Nyssa javanica seedlings in non-sterilized soil had a greater mycorrhizae infection rate, more leaves and grew taller than those in sterilized soil but there were no significant differences in seedling dry weight. For Sapindus rarak there were no significant differences between sterilized and non-sterilized treatments in germination rate, number of leaves and average seedling height or weight, but the seedlings in non-sterilized soil had greater mycorrhizae infection rate than those in sterilized soil. Overall, this study failed to demonstrate that mycorrhizae have a significant effect on seed germination or seedling growth rate for the tree species studied.