Effect of Seasonal Variation on Mycorrhizal Fungi Associated with Medicinal Plants in Central Himalayan Region of India

摘要

This research paper assesses the effect of seasonal variation on mycorrhizal fungi. Based on the richness of medicinal plants in Himalayan region, this research work considered three medicinal plants i.e. Catharanthus roseus Linn., Ocimum spp. and Asparagus racemosus Willd. The study was conducted at five districts of Uttarakhand state of India viz. Pauri Garhwal, Haridwar, Dehradun, Udham Singh Nagar and Almora. To account for seasonal variations, soil and root samples were collected in months of Jan-Feb, May-June and Sep-Oct from year 2006 to 2008. Furthermore, the study was directed to collect information about the distribution of VAM fungi in the medicinal plants in relation to spore population. This research work evaluated and analyzed the effect of temperature, altitude and seasonal conditions. The undisturbed natural vegetations revealed maximum spore numbers followed by cultivated and non-cultivated regions. Similarly, root colonization by VAM fungi was observed at higher levels in natural vegetations and cultivated sites in comparison to non-cultivated lands. The monthly and seasonal temperature varied and had considerable effect on VAM fungal population. The data obtained in the present study undoubtedly indicate that the sea-sonal variation in VAM fungi is significant with few exceptions. VAM fungi in medicinal plants differ in the manner and extent with which root colonization rate occurs and also differ in their capacity to form propagules. Most of the study reveals that host plant had much more effect on spore population. Number of spores also varied with the growing season of the host plant. During the present study most of the sites showed a general increase in spore number from Sep-Oct to Jan-Feb.