Objective: The inoculants mainly nitrogen fixers and phosphate solubilizing microbes had the influence on plant growth attributes. The current study was done to assess the fertilizing activity of A. chroocaccum, B. megathirium strains on growth, yield parameters and nutrient uptake for Sorghum bicolor. Methods: Isolation, identification of the nitrogen fixing bacterium- A. chroocaccum and Phosphate solubilizing microbe- B. megathirium and the growth and yield parameters of Sorghum bicolor as well as NPK uptake levels were studied. Results: A. chroocaccum and B. megathirium exhibited proliferation of microbial-population in soil by synergistic interaction with plants and the application increases the availability of NPK in the soil after harvest of crop. These beneficial inoculants are also known to help in the uptake of some other nutrients. The maximum plant beneficial aspects were noticed in the plants inoculated with 100% recommended dose of fertilizer (RDF)+A. chroocaccum+ B. megathirium and least was noticed in the control plants at all growth stages and at the time of harvest. Conclusion: From the study, it can be concluded that the beneficial effect of A. chroocaccum and B. megathirium is visualized in sorghum crop with improved yield and nutrient uptake. So this species can be used extensively for future inoculation of the Sorghum crop for better growth and development and for good returns in an ecological way.

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The present study is focused on improving the growth and phosphate uptake of leafy vegetables by supplying phosphate bioinoculants. For the study of plant growth and phosphate uptake in leafy vegetables, a total of 41 PSF were isolated, from the 50 rhizosphere soil samples through a serial dilution method using Pikovskaya’s medium. Among them, 6 PSF were selected with maximum solubilization index (3.08 to 3.86) and further evaluated their phosphate solubilization ability under laboratory and field conditions. The selected 6 PSF showed good results in decreased pH (4.0 to 3.1 from initial pH of 6.89), titrable acidity (30.16g/L to 38.08g/L), and concentration of phosphate in culture broth was (60µg to 25µg). With these results, the PSF bio inoculants were prepared and treated with selected seeds of methi and palak under field trials. Among the selected six PSF, PSF 39 (Penicillium oxalicum) showed maximum plant growth and yield in methi, the parameters including plant height and number of leaves (7.8cm, 15 leaves at 15 days after sowing and 10.1cm, 21 leaves at harvest), root length (5.5cm), biomass (2.11g of fresh weight and 1.01g of dry weight) and yield of leafy vegetable (2.01g). The maximum plant phosphorus uptake was recorded in plants (0.393%) and maximum P (Kg/ha) available in the rhizosphere soil was recorded (346.96Kg/ha). PSF 38 (Aspergillus japonicus) showed maximum plant growth and yield in palak, the parameters including plant height and number of leaves (15.7cm, 8 leaves at 15 days after sowing and 30.6cm, 11 leaves at harvest), root length (10.9cm), biomass (11.23g of fresh weight and 3.82g of dry weight) and yield of leafy vegetable (10.32g). The maximum plant phosphorus uptake was recorded in plants (0.369%) and maximum P (Kg/ha) available in the rhizosphere soil was recorded (346.29 Kg/ha).

In the present study, the phosphate-solubilizing fungus was isolated and identified as Aspergillus niger. Its 18S rRNA gene sequence was deposited at GenBank, NCBI (MN904862). For the study of the Phosphate solubilization capacity of the fungus, different rhizosphere soil samples were collected from medicinal plants. 40 fungal colonies were isolated after serial dilution and one fungal colony with high phosphate solubilization zone was selected and further tested. The fungus showed good results in different phosphate solubilization tests, SI (3.91), SE (290), and pH of the culture filtrate after the growth of the fungus decreased from 6.89 to 3.13 due to the production of organic acids. The colour changed from blue to yellow on the agar plate and red to yellow in the broth due to the acidic condition of the media during the growth of the fungus. Titrable acidity was measured at 32.8g/L and 420µg of P was estimated in culture broth by the Vanadomolybdate method. The fungus showed a positive result for siderophore production. 20µg of Indole Acetic Acid (IAA) was produced by the fungus and was estimated by the Salkowaski reagent method using a standard calibration curve. Due to the phosphate solubilization capacity and production of plant growth promoters of A. niger, can be recommended as a Phosphate solubilizer in an agricultural field.