STUDY OF MYCORRHIZA HELPER BACTERIA AND THEIR UTILIZATION IN ENHANCING THE EFFICIENCY OF VAM FUNGI
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Date
2023-11-08
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Acharya N G Ranga Agricultural University
Abstract
Mycorrhiza Helper Bacteria (MHB) forms symbiotic association with ectomycorrhiza and Arbuscular Mycorrhiza (AM) and promotes root-fungus symbiosis. In the present study 40 MHB were isolated from the rhizosphere soils of different crops from different agroclimatic zones of Andhra Pradesh. Among the 40 MHB isolates, most of them were gram positive (+ve) character, rod shaped and few were motile and endodpore formers. 23 isolates were catalase positive, 18 isolates were positive for starch hydrolysis, 37 isolates were positive for MR test, 20 isolates were positive for VP test, 18 isolates were positive for casein hydrolysis, 12 isolates were positive for indole production and only one isolate was positive for H2S production. 55% of isolates were found to be positive for IAA production, maximum P solubilization was shown by the NDLCP2 with Solubilization Index (4.00) and highest potassium Solubilization Index was shown by the strain NDLCP3 (2.7) and among 40 bacterial isolates 38 bacterial isolates were positive for ammonia production.
Based on qualitative screening of MHB isolates for biochemical, physiological and PGPR activity, their influence on in vitro germination of VAM chlamydospores further, by spore production, root colonization and Infective Propagules. The two isolates AMTRG2 and AMTBG8 found efficient among all the 40 MHB isolates screened. These two isolates
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enhanced the quality of VAM by increasing the sporulation, root colonization and Infective propagules. These two isolates were identified as Priestia megaterium (AMTRG2) and Bacillus safensis strain (AMTBG8) by 16S rRNA gene sequencing.
Pot culture experiment was conducted with blackgram crop by application of efficient MHB and VAM fungi along with other bioinoculants. These MHB and VAM along with other bioinoculants increased the growth parameters like plant height (35.00 cm), number of branches per plant (14.50), number of pods per plant (26.75), number of seeds per pod (5.50), shoot and root biomass (5.44 g plant-1 and 0.75 g plant-1 respectively) and 100 seed weight and grain yield (5.42g and 2,665.25 kg ha-1 respectively) also increases.
Other physico chemical properties of soil like PH (7.5), EC (0.62 dS m-1), organic carbon(0.42%), soil aggregate stability(13.77%), bulk density (1.35 g cm-3) and enzymes like dehydrogenase activity (50.41μg TPF g-1 soil day-1), acid phosphatase (73.42 μg pNP g-1 soil h-1) and alkaline phosphatase (70.94 μg pNP g-1 soil h-1), N, P, K uptake in concentration in stover (1.28%, 0.48% and 3.05% respectively) available nitrogen, phosphorus and potassium content of the rhizosphere soil (267 kg ha-1 , 81.42 kg ha-1 and 632 kg ha-1) microbial population of rhizosphere soil, AMF spore load (67.75 spores per 10 g soil)and AMF per cent root colonization (92.57%) was highest in T5 (VAM with MHB(7) + Rhizobium +PSB +KRB). This study clearly showed that MHB strains and AMF along with other bioinoculants significantly increased the VAM spore load, VAM per cent root colonization i.e., increased the efficiency of AM fungi and improved the microbial population, available NPK in soil, nutrient uptake NPK in plant, soil enzyme activities and growth and yield of blackgram when compared to the uninoculated control. Thus these two efficient MHB isolates can be better utilized for crop production and AM inoculum production.