Crop Science and Agriculture

Plant Growth Promoting Rhizo microorganisms (PGPRs) are more commonly known as benefi cial microbial inoculants that can improve soil fertility and crop productivity. Now-a- days, the application of the liquid plant growth promoting microbial consortia in the vegetable production is gaining lot of importance because of their cost eff ectiveness and eco-friendliness. Diff erent liquid plant growth promoting rhizo microbial consortia like Azospirillum, Azotobacter, phosphorus and potash solubilizing bacteria etc., are used in the fi eld of vegetable production for increasing the yield and to reduce diseases and also to maintain the soil health for sustainable production. In the present study, attempts were made to isolate, characterize and screen native nitrogen fi xing, phosphorus and potassium solubilizing bacteria from the diff erent weed rhizosphere soils of Malnad region of Karnataka (India). Further, attempts were also made to develop and evaluate the eff ective liquid PGPR consortia on

growth and yield of radish under greenhouse conditions. Out of 11 diff erent weed rhizosphere soils collected, as many as 7 Azotobacter, 6 phosphate solubilizing and 8 potassium solubilizing isolates were obtained. In the in vitro screening studies, the Azoto-7, PSB-2 and KSB-8 showed high effi ciency in nitrogen fi xation, phosphorus and potassium solubilization, respectively and all the effi cient isolates were tentatively characterized as Azotobacter, phosphate solubilizing Bacillus megaterium and potassium solubilizing Bacillus mucilaginosus based on morphological and biochemical characters. Further, the effi cient liquid plant growth formulation were developed and evaluated on Radish under greenhouse condition using varied levels of Recommended Dose of Fertilizers (RDF). Out of 16 treatments imposed, the treatment receiving 75% of RDF+FYM+efficient liquid PGPR formulation showed statistically highest germination percentage (100%) and number of leaves (15.70, 18.60 and 20.20 numbers of leaves at 15, 30 and 45 days aft er sowing). Similarly, the same treatment showed high chlorophyll content of 2.90 mg/g of tissue, fresh and dry weight of 141.10 and 29.90 g, respectively followed by the treatment receiving 100% of RDF+FYM+efficient liquid PGPR formulation. However, the same trend of observation was recorded with respect to tuber girth, tuber length and also showed the maximum accumulation of NPK content both in plant and soil at the time of harvest. Scale up studies further required evaluating the native PGPR formulations for diff erent crops in combination with different bio-control agents for increased vegetable production.