Two biofertilizer agents, Azospirillum amazonense A10 and Bacillus megaterium P7, alone and in co... more Two biofertilizer agents, Azospirillum amazonense A10 and Bacillus megaterium P7, alone and in combination increased the grain yield of rice in autoclaved soil by 103-256% over control. Colonies of A, amazonense and B. megaterium were distinguished from the contaminant phosphate solubilizing bacteria (PSB) and Azospirilla colonies in the respective media based on colony morphology, colour and thickness of clearing zone, Population densities of A, amazonense and B. megaterium were found to be 2.6 x 10 8 and 2.9 x 10 8 CFUg .] soil, respectively at 48 day post transplanting. Protein and antibiotic resistance profiles of the inoculated and reisolated A. amazonense, B. megaterium and the contaminant colonies with the pure cultures indicated that the isolates were able to establish in the rice rhizosphere with the resultant enhancement of plant growth and yield.
A Crop coefficient (k c) was determined for Capsicum annumm L. (hot pepper) with the help of UMS-... more A Crop coefficient (k c) was determined for Capsicum annumm L. (hot pepper) with the help of UMS-GmBH cylindrical field lysimeter of 30 cm diameter and 120 cm deep and Penman-Monteith FAO-56 model. Penman-Monteith model is the universally adopted standard model for estimation of reference evapo-transpiration (ET 0) based on local weather parameters. Eight other models viz. Modified Penman Method, Hargreaves equation, Samini Hargreaves equation, Thorthwaite equation, Solar Radiation Method, Net Radiation Method, Blaney-Criddle Method and Radiation Method were also used for estimation of ET 0 and compared with Penman-Monteith model to find out the accuracy of prediction with limited weather parameters. Scatter plot and paired t-test were used for comparison. Out of all these models, Blaney-Criddle Method was found to yield similar results as given by Penman-Monteith model. The values of crop evapo-transpiration (ET c) were varying from 1.11 mm d-1 to 3.12 mm d-1. k c is the ratio of ET c to ET 0. The highest kc value was obtained during the maximum vegetative growth in 8th week after transplantation. The crop-coefficients for three growth stages viz. initial, mid and maturity were found to be 0.33, 0.64 and 0.30, respectively.
Properties of the effluent of Nagaon paper mill at Jagiroad, Assam and typical acid soils receivi... more Properties of the effluent of Nagaon paper mill at Jagiroad, Assam and typical acid soils receiving either this effluent or shallow tube well (STW) irrigation for 17 years were analyzed. The effluent was alkaline in reaction (pH 7.6, EC 2.5 dS m -1) and contained high levels of dissolved salts, bases and chloride. The pH of the effluent irrigated soil was observed to be 1.3 units higher due to effluent irrigation. Soil salinity (EC) was increased by more than three times. Similarly, CEC, base saturation, total and water soluble basic cations, ESP and SAR were significantly more in the effluent irrigated soil. The chloride concentration of the effluent irrigated soil was 197 mg kg -1 against 43 mg kg -1 observed in the STW irrigated soil. Although, rise in soil pH, CEC and base saturation are desirable for biological activity in acidic soils, the effluent irrigated soils showed rather very low value of microbial biomass carbon content. Overall, the effluent altered the soil character...
Organic farming is being proposed as a measure to restore sustainability of agriculture productio... more Organic farming is being proposed as a measure to restore sustainability of agriculture production, with an eye on maintaining environmental amenity at the same time. Although it has made remarkable progress in recent times, the scientific community stands rather skeptical about the ability of organic agriculture to produce enough food to feed the fast-growing population throughout the world. Despite being recognized to offer some health and environmental benefits, its low-yield potential with respect to conventional farming, and inadequate availability of organic inputs to meet the crop nutrient requirements are some constraints that put in jeopardy its future prospect as a universally acceptable alternative agriculture system. In view of these contrasting opinions, the present review attempts to explore the extent, distribution, merits and limitations of the organic agriculture. Possible impact of organic farming on soil health and India’s food security is also discussed.
Molecular and functional characteristics of seven azospirilla and five phosphorus solubilizing ba... more Molecular and functional characteristics of seven azospirilla and five phosphorus solubilizing bacteria (PSB) isolates of rice rhizosphere, growth promotion ability of two efficient strains, Azospirillum amazonense A10 (MTCC4716) and Bacillus megaterium P5 (MTCC4714) and their persistence based on streptomycin resistant derivatives (SRD), were determined. SDS-PAGE and isozyme banding patterns of the isolates were used to arbitrarily group the azospirilla into 4 and PSB into 3 clusters and as markers to ascertain their identity. The azospirilla produced 2.0 to 10.5 ppm of IAA like substances and showed nitrogenase activity of 0.02 to 3.55 nmole C2H4/hr/ml of pure culture. PSB isolates produced 7.8 to 15.0 ppm IAA like substances and 20 to 128 ppm soluble P. Induction of resistance to streptomycin resulted in changes of these properties. Co-inoculation of rice with SRD A10 and SRD P5 and their parental strains in separate treatments enhanced grain yield over control by 31 and 12.4%, r...
Three groups of rhizobacteria were isolated using three selective culture media from the rhizosph... more Three groups of rhizobacteria were isolated using three selective culture media from the rhizosphere of rice grown at fifteen locations in Assam. Four bacteria in each group were selected for taxonomic identification, characterization and also for screening the superior isolates to promote rice growth. The isolates of phosphate-solubilizing and fluorescent bacterial groups were found to be eight different species. The three isolates of azospirilla group were identified as Azospirillum brasilense and the fourth isolate was identified as Azospirillum amazonense. RAPD analysis of the Azospirillum isolates indicated that azospirilla were four distinct genotypes. These bacterial strains showed differences in growth pattern, IAA production level (2.0-21.6 μg/ml of culture supernatant), antibiotic resistance profile and nitrogenase activity (0.33-0.75 nmol C2H4 h-1 100-cc root volume) in the inoculated roots. A. amazonense A10 (MTCC 4716), Bacillus pantothenticus P4 (MTCC 4695) and Pseudom...
Two biofertilizer agents, Azospirillum amazonense A10 and Bacillus megaterium P7, alone and in co... more Two biofertilizer agents, Azospirillum amazonense A10 and Bacillus megaterium P7, alone and in combination increased the grain yield of rice in autoclaved soil by 103-256% over control. Colonies of A, amazonense and B. megaterium were distinguished from the contaminant phosphate solubilizing bacteria (PSB) and Azospirilla colonies in the respective media based on colony morphology, colour and thickness of clearing zone, Population densities of A, amazonense and B. megaterium were found to be 2.6 x 10 8 and 2.9 x 10 8 CFUg .] soil, respectively at 48 day post transplanting. Protein and antibiotic resistance profiles of the inoculated and reisolated A. amazonense, B. megaterium and the contaminant colonies with the pure cultures indicated that the isolates were able to establish in the rice rhizosphere with the resultant enhancement of plant growth and yield.
A Crop coefficient (k c) was determined for Capsicum annumm L. (hot pepper) with the help of UMS-... more A Crop coefficient (k c) was determined for Capsicum annumm L. (hot pepper) with the help of UMS-GmBH cylindrical field lysimeter of 30 cm diameter and 120 cm deep and Penman-Monteith FAO-56 model. Penman-Monteith model is the universally adopted standard model for estimation of reference evapo-transpiration (ET 0) based on local weather parameters. Eight other models viz. Modified Penman Method, Hargreaves equation, Samini Hargreaves equation, Thorthwaite equation, Solar Radiation Method, Net Radiation Method, Blaney-Criddle Method and Radiation Method were also used for estimation of ET 0 and compared with Penman-Monteith model to find out the accuracy of prediction with limited weather parameters. Scatter plot and paired t-test were used for comparison. Out of all these models, Blaney-Criddle Method was found to yield similar results as given by Penman-Monteith model. The values of crop evapo-transpiration (ET c) were varying from 1.11 mm d-1 to 3.12 mm d-1. k c is the ratio of ET c to ET 0. The highest kc value was obtained during the maximum vegetative growth in 8th week after transplantation. The crop-coefficients for three growth stages viz. initial, mid and maturity were found to be 0.33, 0.64 and 0.30, respectively.
Properties of the effluent of Nagaon paper mill at Jagiroad, Assam and typical acid soils receivi... more Properties of the effluent of Nagaon paper mill at Jagiroad, Assam and typical acid soils receiving either this effluent or shallow tube well (STW) irrigation for 17 years were analyzed. The effluent was alkaline in reaction (pH 7.6, EC 2.5 dS m -1) and contained high levels of dissolved salts, bases and chloride. The pH of the effluent irrigated soil was observed to be 1.3 units higher due to effluent irrigation. Soil salinity (EC) was increased by more than three times. Similarly, CEC, base saturation, total and water soluble basic cations, ESP and SAR were significantly more in the effluent irrigated soil. The chloride concentration of the effluent irrigated soil was 197 mg kg -1 against 43 mg kg -1 observed in the STW irrigated soil. Although, rise in soil pH, CEC and base saturation are desirable for biological activity in acidic soils, the effluent irrigated soils showed rather very low value of microbial biomass carbon content. Overall, the effluent altered the soil character...
Organic farming is being proposed as a measure to restore sustainability of agriculture productio... more Organic farming is being proposed as a measure to restore sustainability of agriculture production, with an eye on maintaining environmental amenity at the same time. Although it has made remarkable progress in recent times, the scientific community stands rather skeptical about the ability of organic agriculture to produce enough food to feed the fast-growing population throughout the world. Despite being recognized to offer some health and environmental benefits, its low-yield potential with respect to conventional farming, and inadequate availability of organic inputs to meet the crop nutrient requirements are some constraints that put in jeopardy its future prospect as a universally acceptable alternative agriculture system. In view of these contrasting opinions, the present review attempts to explore the extent, distribution, merits and limitations of the organic agriculture. Possible impact of organic farming on soil health and India’s food security is also discussed.
Molecular and functional characteristics of seven azospirilla and five phosphorus solubilizing ba... more Molecular and functional characteristics of seven azospirilla and five phosphorus solubilizing bacteria (PSB) isolates of rice rhizosphere, growth promotion ability of two efficient strains, Azospirillum amazonense A10 (MTCC4716) and Bacillus megaterium P5 (MTCC4714) and their persistence based on streptomycin resistant derivatives (SRD), were determined. SDS-PAGE and isozyme banding patterns of the isolates were used to arbitrarily group the azospirilla into 4 and PSB into 3 clusters and as markers to ascertain their identity. The azospirilla produced 2.0 to 10.5 ppm of IAA like substances and showed nitrogenase activity of 0.02 to 3.55 nmole C2H4/hr/ml of pure culture. PSB isolates produced 7.8 to 15.0 ppm IAA like substances and 20 to 128 ppm soluble P. Induction of resistance to streptomycin resulted in changes of these properties. Co-inoculation of rice with SRD A10 and SRD P5 and their parental strains in separate treatments enhanced grain yield over control by 31 and 12.4%, r...
Three groups of rhizobacteria were isolated using three selective culture media from the rhizosph... more Three groups of rhizobacteria were isolated using three selective culture media from the rhizosphere of rice grown at fifteen locations in Assam. Four bacteria in each group were selected for taxonomic identification, characterization and also for screening the superior isolates to promote rice growth. The isolates of phosphate-solubilizing and fluorescent bacterial groups were found to be eight different species. The three isolates of azospirilla group were identified as Azospirillum brasilense and the fourth isolate was identified as Azospirillum amazonense. RAPD analysis of the Azospirillum isolates indicated that azospirilla were four distinct genotypes. These bacterial strains showed differences in growth pattern, IAA production level (2.0-21.6 μg/ml of culture supernatant), antibiotic resistance profile and nitrogenase activity (0.33-0.75 nmol C2H4 h-1 100-cc root volume) in the inoculated roots. A. amazonense A10 (MTCC 4716), Bacillus pantothenticus P4 (MTCC 4695) and Pseudom...
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Papers by Dwipendra Thakuria