Genetic assessment for weed suppressive ability and Vesicular Arbuscular Mycorrhiza VAM association of rice Oryza sativa L cultivars in organic culture condition

Abstract

Rice cultivation in direct seeded condition encounter a lot weed pressure as newlinecompared to wet condition leading to considerable yield loss. Organic direct seeded newlinerice face two major constraints in the early growth stage viz. profound weed newlinecompetition and poor soil nutrient availability due to non-application of inorganic newlinefertilizers. This makes the situation challenging because of lower production. newlineDevelopment of a weed suppressive variety coupled with higher Vesicular Arbuscular newlineMycorrhiza (VAM) colonization in the root might be a wholesome approach to newlinemitigate the overall weed problem, water scarcity and poor nutritional status of direct newlineseeded organic production system. An effort was made in the present investigation to newlinestudy the genetic variability with respect to weed suppressive ability and VAM newlinecolonization rate among 50 rice genotypes grown by the farmers in the north eastern newlineIndia. The genotypes comprised of Jhum, Ahu and Sali cultivars (including joha, bora newlineand bao rice). Attempt was also made to elucidate the inter relationships among newlinedifferent morphological traits contributing to weed suppressive ability and VAM newlinecolonization. Path coefficient analysis was used to study the direct and indirect effects newlineof different morphological characters on weed suppressive ability and VAM newlinecolonization. Half diallel analysis was carried out to study the gene effects of the two newlinecharacters and identification of parental genotypes having good combining ability and newlinesuitable cross combinations. To assess the weed suppressive ability and VAM response, newlineexperiments were carried out in the field condition (in Weedy and weed-free newlineenvironments) and pots (in VAM inoculated soil and control environments) newlinerespectively. newlineThe yield loss of the genotypes due to weed infestation ranged from 15.08% newline(cultivar Inglongkiri) to 73.03% (cultivar Jhummalati). The decline in harvest index newlinedue to weed pressure was also observed in some genotypes though there was no newlinecoherence in harvest index decline and loss in yield. Marked variation was obser...