Distribution of Arbuscular Mycorrhizae Associated with Coconut and Arecanut Based Cropping Systems

Abstract

Mycorrhizal fungi are widespread in agricultural systems and are especially relevant for organic agriculture. A study was conducted to assess diversity in the arbuscular mycorrhizal (AM) fungi associated with coconut and arecanut intercropping systems of Kasaragod and Thiruvananthapuram districts of Kerala. Mycorrhizal parameters like spore density, root colonization, species richness, and relative occurrence of species were recorded. Coconut cropping system was found to be densely vegetated with diverse AM fungi, Glomus spp., Gigaspora spp., and Acaulospora spp. The diversity of fungal species was found to be maximum in the high density multiple species cropping system plot of CPCRI, Kasaragod with coconut as the main crop and banana, pepper as intercrops and least in farmers’ plot of Mogral Puthur, Kasaragod with arecanut as main crop and banana as the intercrop. A total of fourteen AM fungi were identified from coconut and arecanut intercropping systems. Glomusaggregatum, Funneliformis mosseae, and Rhizophagus fasiculatum were observed in both the cropping systems studied. Among the six edaphic factors analysed, an inverse relationship of mycorrhizal population with soil pH and soil phosphorous was observed. An abundance of P-solubilizers, fluorescent Pseudomonas spp., N-fixers, Bacillus spp., and Trichoderma spp. were observed in the rhizosphere, with Bacillus spp. showing the maximum association with AM fungi. The higher AMF colonization in coconut cropping system imply that the AM fungi colonization is primarily dependent on the host plant rather than the climatic/edaphic components of an area.