FORMULATION OF LIQUID RHIZOBIAL BIOFERTILIZER AND ITS VALIDATION
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Date
2018
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AAU, Jorhat
Abstract
The present study on “Formulation of liquid rhizobial biofertilizer and its validation” was carried out in the laboratory of the Biofertilizer Production Unit, Department of Soil Science, Assam Agricultural University, Jorhat during 2017-18. The objective of this investigation was to determine the shelf-life of the liquid formulation, to study the nodulation pattern and establishment of added rhizobia in specific host legumes and to ascertain the validation of the effective liquid formulation on pea, green gram and black gram. The experiment was laid in a Completely Randomised Block Design. The individual strains of greengram(Rhiz-10) and blackgram(Rhiz-13) was diluted to different formulations of 25, 50, 75 and 100 per cent and shelf-life was examined in comparision with a solid substrate at 0, 30, 60, 90 and 120 days of incubation. Results showed that viable population of rhizobia could be maintained with different formulations even upto 120 days. Whereas, in solid substrate the viable population started decreasing more, as days of incubation increased irrespective of pulse crops . The colony forming unit in 100 per cent liquid formulation ranged from 1.2 to 3.2x108 cfu/ml in greengram and 1.7 to 2.4x108 cfu/ml in blackgram from 0 to 60 days of incubation. Nodulation pattern was studied in terms of infectivity test for three crops viz. pea, greengram and blackgram under sterile condition using Gibson tube method. The three rhizobial strains (Rhiz-25, Rhiz-10 and Rhiz-13) of different concentrations of 25, 50, 75 and 100 per cent was prepared and inoculated in tubes and some tubes were kept as control. At 20th day of inoculation, nodule number, nodule dry weight and establishment (cfu/nodule) was found to be highest for all the three crops on application of 100 per cent liquid formulation. The establishment of rhizobia per nodule at 100 per cent liquid formulation for pea, green gram and blackgram was recorded to be 5.6, 7.3 and 5.0x103 cfu/nodule respectively. For validation, a pot culture study was conducted using pulses like pea, greengram and blackgram under unsterile condition with respective rhizobial formulation of 50 and 100 per cent concentration. The replicated plants were grown for 60 days and thereafter harvested. The results showed that nodulation pattern (nodule number and dry weight), and yield parameters increased significantly over uninoculated control at 50 and 100 per cent formulation. Rhizobia got well established in treated pots. Further, enzyme activities of the soil with respect to inoculated crops also increased indicating enhanced rhizobial activity. The numerical data on yield recorded for pea, greeengram and blackgram were 25, 18 and 12 pods per plant at 100 per cent rhizobial formulation. Similarly, enzyme activities also increased from 26.66 to 35.52 μg TPF g-1 24 h-1 DHA, 1.63 to 2.57 μg fluorescein g-1 30 mins-1 FDA and 12.12 to 16.58 μg p-nitrophenol/gm/hr PMEase for soil grown with pea at 100 per cent rhizobial formulation and similar trend of result also showed in soil planted with greengram and blackgram.