Seasonal variations of arbuscular mycorrhizal fungal association with Ipomoea pes-caprae of coastal sand dunes, Southern India.

Two years seasonal studies on arbuscular mycorrhizal (AM) fungi associated with Ipomoea pes-caprae established on the coastal sand dunes of the west c oast of India yielded 41 species belonging to six genera. The percent root colonization by the AM fungi was least during monsoon (28.7-64.6%) and high est during post-monsoon (80.6-93.6%), but the mean spore density in rhizosp here was least during post-monsoon (9.5-35/100 g) and highest during summer season (58.2-132.5/100 g). The species belonging to the genus Glomus were most common (51%). Colonization of roots was strongly correlated with the r hizosphere moisture, pH, organic carbon, calcium, sodium, potassium, nitrog en and phosphate (p > c.v.), whereas only organic carbon, calcium and phosp hate showed significant correlation (p > c.v.) with species richness and sp ore density. The high levels of colonization, spore density, species richne ss and correspondence of AM fungal phenology with host plant phenology migh t have increased the fitness of Ipomoea pes-caprae for successful establish ment on the sand dunes of west coast of India.