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Influence of different phosphorus concentrations was studied in four rice varieties (Akhanphou, MTU1010, RP BIO 226, and Swarna) differing in their tolerance to low phosphorus. There was an increase in shoot and root dry mass with the increase in phosphorus concentration. At the low phosphorus concentration at both tillering and reproductive stages, Swarna, followed by Akhanphou, recorded maximum biomass for both roots and shoots, while the minimum was observed in RP BIO 226. Reduction in photosynthetic rate, stomatal conductance, transpiration rate, and internal CO 2 concentration at low phosphorus concentrations were observed at both tillering and reproductive stages in all the genotypes. In low phosphorus, maximum photosynthetic rate was found in Swarna followed by Akhanphou. Phosphorus deficiency did not alter the maximum efficiency of PSII photochemistry, however, there was a reduction in effective PSII quantum yield, electron transport rate, and coefficient of photochemical quenching, while the coefficient of nonphotochemical quenching was higher in the low phosphorus-treated plants. Prolonged exposure to excessive energy and failure to utilize the energy in carbon-reduction cycle induced the generation of reactive oxygen species, which affected PSII as indicated by the fluorescence traits. The reduction was less severe in case of Swarna and Akhanphou. The activities of superoxide dismutase, peroxidase, and catalase increased in roots under low phosphorus concentration indicating that photoprotective mechanisms have been initiated in rice plants in response to phosphorus deficiency. Comparatively, Swarna and Akhanphou exhibited a higher biomass, higher photosynthetic rate, and better reactive oxygen species-scavenging ability which conferred tolerance under low phosphorus conditions.

Continuous use of fertilizers decreasing the biological activity of the soil. Fertile soils teem with microorganisms, which directly contribute to the biological fertility of the soil. Microorganisms are responsible for the availability of nutrients to the plants which are already exist in the soil. Hence, the present study focused on to investigate the effect of natural farming on soil microorganisms and enzymes activity of maize rhizospherein comparison with inorganic and organic farming during the autumn season of 2016-17 at Agricultural College, Jagtial. The results of the investigation revealed that the population of microbes (bacteria and fungi) at 30, 60 Days After Sowing (DAS) and harvest was unaffected by variety (Aswini) or hybrid (DHM 117). But, among the different farming methods, organic farming recorded higher bacterial (19, 29 and 22.5 x 10-7 CFU{Colony Forming Unit} g-1 dry soil) and fungi (8.25, 14.67 and 10.25 x 10-5 CFU g-1 dry soil) population at 30, 60 DAS and harvest stage respectively and significantly superior to inorganic and natural methods. The microbial population in inorganic method was inferior to that in absolute control similar to microbial population, highest urease activity was recorded in organic method at 30, 60 DAS and harvest (52.92, 68.33 and 33.25 µg NH4+ g-1 2 h-1, respectively) and it was superior to inorganic and natural farming which were at a par with each other. Significantly higher activity of dehydrogenase was observed with organic farming at 30, 60 DAS and harvest (1.65, 2.29 and 1.72 µg TPF g-1 day-1) compared to natural farming and inorganic farming. The activity of urease and dehydrogenase remained similar with DHM 117 or Aswini.

The effect of inorganic phosphorus, phosphate solubilising bacteria and vermicompost on yield of greengram and available nutrient status was studied during Kharif 2016 at Agricultural College, Polasa, Jagtial, Telangana state, India. The experiment was conducted with three levels of phosphorus (0, 75 and 100 % RDP), phosphate solubilising bacteria (0 and 2 kg ha -1 ) and vermicompost (0 and 5 t ha -1 ). The results revealed that grain and haulm yields were increased with increasing inorganic P levels and when the crop was supplemented with PSB and vermicompost. Significantly higher grain (1033.33 kg ha -1 ) and haulm yield (1625.66 kg ha -1 ) were recorded when the crop was integrated with 100 % RDP along with PSB and vermicompost. Results also indicated that there was a significant build-up in available N, P, K and S status with increasing inorganic P levels, seed inoculation with PSB and vermicompost application. Thus, it shows positive influence by the application of phosphatic fertilizers, organic manures and biofertilizers.