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ThesisItem Open Access Development of bacterial consortium to improve green manure degradation and nutrient availability in kharif maize(Punjab Agricultural University, Ludhiana, 2019) Jaspreet Kaur; Gosal, S.K.The present investigation was conducted to isolate cellulose degrading bacteria with plant growth promoting traits to enhance green manure (Crotolaria juncea) decomposition as well as nutrient mineralization in maize crop. A total of 75 different bacteria were isolated from soil samples collected from various locations. Only 20 isolates were selected on their ability to degrade cellulose. Cultural and morphological characterization showed that most of these bacterial isolates were gram positive, non-motile and non-endospore forming cocci. Biochemical characterization of the isolates revealed that most of these isolates were positive for oxidase, catalase, methyl red, starch and citrate utilization test. Only two bacterial isolates (CD4 and CD6) were urease positive, one (CD11) was indole positive and three (CD1, CD11 and CD15) were found to HCN positive. Functional characterization of these isolates showed that the isolates CD2 and CD9 had highest cellulase (27.543 mg/ml) and β-glucosidase activity (15.46 μg pNP released/ml), respectively. Highest IAA production (42.25 μg/ml), phosphorous solubilization index (1.80) and quantitative P- solubilization (25.39 μg/ml) were recorded for CD9 bacterial isolate. All the isolates were found to have nitrogen fixing ability. The maximum amount of ammonia (6.659 μM/ml) was excreted by isolate CD18 on N-free Jensen‟s medium. On the basis of functional characteristics, three best isolates (CD2, CD9 and CD14) were evaluated for green manure decomposition and nutrient mineralization studies, under pot conditions under different soil (sterilized and unsterilized) and moisture regimes (aerobic and flooded). The application of isolates as consortium was found best for increasing green manure decomposition, nutrient mineralization and soil biological activities relative to uninoculated control treatments. These effects of consortium inoculation were found more pronounced in aerobic conditions as compared to flooded conditions. A field experiment was conducted for two consecutive years (2016 and 2017). A significant decomposition of green manure was observed with application of CDBC biofertilizer within the period of seven days in field condition. A total of eight treatments having different combinations of biofertilizer (CDBC), green manure and inorganic nitrogen fertilizers (75% and 100%) were used to study their effect on soil microbial dynamics, soil chemical properties and yield of maize crops (var. PMH1 and var. PMH4). Microbial population (total bacteria, fungi, P-solubilizer, amylolytic and cellulolytic bacteria) and enzymatic activities (dehydrogenase, alkaline phosphatase, urease, cellulase, amylase and invertase) in maize rhizosphere significantly increased in treatments having integrated application of CDBC, green manure and 100% whereas, soil actinomycetes and diazotrophic population were found highest in treatments with sole application of inorganic nitrogen fertilizer. Higher soil microbial populations and enzymatic activities were observed during second year of field study relative to first year. Soil chemical properties viz., electrical conductivity, organic carbon, available nitrogen, available phosphorous and potassium content were found highest under integrated application of CDBC with green manure and recommended dose of nitrogen fertilizer whereas soil pH varied non-significantly among the treatments. Maximum plant height, yield attributes and yield were observed in same treatment. The results indicated that application of CDBC biofertilizer not only decreased the fallow period of green manure decomposition but also enhanced soil health, fertility and yield of maize crop. So, application of CDBC along with green manure and inorganic nitrogen fertilizer can serve as sustainable agricultural practice for maize cultivation.