MAXIMIZING THE SHELF LIFE OF MONOXENICALLY PRODUCED CARRIER-BASED AM FUNGAL BIO-INOCULA FOR MAINTAINING ITS LONG-TERM VIABILITY

Arbuscular mycorrhizal (AM) fungi are often applied as bio-inoculants due to their plant growth promoting benefits. The objectives of the present work were to maximize the shelf life of monoxenically produced carrier-based AM fungal bio-inocula of Rhizoglomus intraradices and Funneliformis mosseae. Shelf life of in vitro produced inoculum was studied by assessing the infectivity potential of in vitro produced inocula in an optimum carrier formulation (vermiculite: cow dung powder: wood powder: wood ash in the ratio of 20:8:2:1) during storage at three different temperatures viz., 4 °C, 25 °C and room temperature (RT). The re-germination potential of in vitro produced spores from carrier-based inocula to in vitro conditions was also examined. The in vitro produced inocula stored at 25 °C remained viable up to 6 mo in the organic carrier formulation. 100 % germination was recorded when the spores of both AM species were cultured back to in vitro conditions indicating high viability, and efficiency of the carrier formulation in maintaining vigour of in vitro produced propagules

Organic amendment increases arbuscular mycorrhizal fungal diversity in primary coastal dunes

Plastic pots were inserted beneath seedlings of a shallow-rooted C4 grass species, Ischaemum indicum, with and without a root-impenetrable nylon sachet filled with organic matter (OM) amendment, at seven stations along an interrupted belt transect in which plant community and soil chemistry had been previously surveyed. The transect was perpendicular to mean high-water mark (MH-WM) across a primary coastal dune system in Goa, India, where summer monsoon is the predominant weather feature. The Quadrat survey of plant frequency was made in stations when the above-ground biomass was estimated to be highest. Arbuscular mycorrhiza fungal (AMF) spore density and diversity were determined morphologically in amended and control pots soils, and in OM sachet residues, after host-plant desiccation when monsoon rains had ceased. Twenty-seven AM fungal spore morphotypes were isolated from the pots containing OM amended rhizosphere soils, 19 from controls and 14 from OM residues in the sachets. Gigaspora margarita proved to be the dominant spore in all treatments. Eight morphotypes recovered from amended pots were not recovered from the controls. There was an increasing trend in species diversity in amended pots away from MH-WM. Spore recovery from the three regimes showed variable distribution that indicated differing AMF species strategies

ARBUSCULAR MYCORRHIZAL FUNGI ASSOCIATED WITH VARIETIES OF Carica papaya L. IN TROPICAL AGRO-BASED ECOSYSTEM OF GOA, INDIA.

The occurrence of arbuscular mycorrhizal (AM) fungi was investigated in six varieties of Carica papaya L in tropical agrobased ecosystem of Goa, India. All the varieties selected for the survey viz., CO-1, Coorg honeydew, CO-2, Sunrise solo, Washington and Local were colonized with arbuscular mycorrhizal fungi. The root colonization ranged from 26 % to 77 %, while the spore density ranged from 100 spores/100g rhizosphere soil to 236 spores/100g rhizosphere soil. Analysis of variance revealed that total nitrogen, available potassium and organic carbon content of the rhizosphere soil along with root colonization and spore density of arbuscular mycorrhizal varied significantly in different varieties of Carica papaya L. Macronutrients like available phosphorus and available potassium recorded significant negative correlation with spore density of arbuscular mycorrhizal fungi. However organic carbon, available phosphorus and total nitrogen recorded significant positive correlation with root colonization of arbuscular mycorrhizal fungi. Thirteen species of arbuscular mycorrhizal fungi belonging to four genera viz., Acaulospora, Glomus, Gigaspora and Scutellospora were found to be associated with six varieties of Carica papaya L. studied

APPLICATIONS OF ARBUSCULAR MYCORRHIZAL FUNGI IN AGROECOSYSTEMS

Arbuscular mycorrhizal fungi belong to phylum Glomeromycota, which are main component of the soil microbiota in most agroecosystems and form symbiotic association with most of the plants. By forming an extended, intricate hyphal network, AM fungi can efficiently absorb mineral nutrients from the soil and deliver them to their host plants in exchange for carbohydrates. They facilitate nutrient uptake, particularly with respect to immobile nutrients, such as phosphorus and enhance tolerance to drought, disease resistance, building up a macroporous structure of soil that allows penetration of water and air and prevents erosion, enhance photosynthesis and reduce stresses during micropropagation. Thus the present review focuses on nutritional and non-nutritional benefits of arbuscular mycorrhizal fungi in agroecosystems

Organic amendment increases arbuscular mycorrhizal fungal diversity in primary coastal dunes

Plastic pots were inserted beneath seedlings of a shallow-rooted C4 grass species, Ischaemum indicum, with and without a root-impenetrable nylon sachet filled with organic matter (OM) amendment, at seven stations along an interrupted belt transect in which plant community and soil chemistry had been previously surveyed. The transect was perpendicular to mean high-water mark (MH-WM) across a primary coastal dune system in Goa, India, where summer monsoon is the predominant weather feature. The Quadrat survey of plant frequency was made in stations when the above-ground biomass was estimated to be highest. Arbuscular mycorrhiza fungal (AMF) spore density and diversity were determined morphologically in amended and control pots soils, and in OM sachet residues, after host-plant desiccation when monsoon rains had ceased. Twenty-seven AM fungal spore morphotypes were isolated from the pots containing OM amended rhizosphere soils, 19 from controls and 14 from OM residues in the sachets. Gigaspora margarita proved to be the dominant spore in all treatments. Eight morphotypes recovered from amended pots were not recovered from the controls. There was an increasing trend in species diversity in amended pots away from MH-WM. Spore recovery from the three regimes showed variable distribution that indicated differing AMF species strategies