Influence of rice-legumes intercropping on native vesicular-arbuscular mycorrhizal association in rice

Rice is one of the major food grain crops of the rainfed upland farmers, practicing mostly subsistence farming. Drought and consequent poor nutrients uptake are the major constraints for low rice productivity in this fragile ecosystem. The symbiotic association of Vesicular-arbuscular mycorrhiza (VAM) is known to facilitate water and nutrients uptake in plants. Water and nutrient uptake in mycorrhizal plants are improved predominantly by increasing effective root surface area of plants through extramatrical mycelial network of VAM fungi leading to greater exploration of soil beyond root hairs (1). The soils of the target ecosystem were found to harbor VAM fungi (Glomus being predominant genus) and upland ricewas observed to be colonized by native VAMF (6).VAM dependency of upland rice for phosphorus acquisition had also been reported (7). Thus, enhancing native VAM association in upland rice could partially mitigate drought and improve nutrientsacquisition. The preliminary study revealed that, colonization of native VAMF in upland rice was enhanced when intercropped with legumes (6). Having this information, systematic efforts were made in the present study to investigate the possible role of rice - legumes intercropping systems to enhance native VAM association in upland rice and also to evaluate different rice legumes intercropping systems for identifying suitable systems that would induce higher VAM association in upland rice.