Arbuscular mycorrhizal status of polycarpaea corymbosa (Caryophyllaceae) on sand dunes of West Coast of India

Mycorrhizal status of the species belonging to the family Caryophyllaceae is inconsistent. Therefore a survey was performed to understand arbuscular mycorrhizal (AM) fungal association and distribution of a seasonal plant species, Polycarpaea corymbosa on the coastal sand dunes of west coast of India. These plants are growing in mixed and pure stands at about 40 m away from the low tide level. The plant biomass was higher in mixed stands than in pure stands. Roots recovered from mixed stands revealed the presence of arbuscules and vesicles, but none of the roots of pure stands showed AM fungal colonization. Spores of 10 and eight species of AM fungi were encountered from the rhizosphere of mixed and pure stands respectively. The spore population and species numbers were high in the rhizosphere of mixed stands. Several rhizosphere edaphic features showed significant difference between mixed and pure stands. This study reveals that the distribution of P. corymbosa on coastal sand dunes is dependent on the soil phosphate. The AM colonization was found to be dependent on rhizosphere pH and moisture. The level of AM colonization was higher during the period of flowering (September). These plants are facultatively mycorrhizal and may acquire AM fungi in mixed stands in order to compete for nutrition with other sand dune plants.