Characterisation of rhizobacteria for growth and yield enhancement of kharif mung bean (Vigna radiata)
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Date
2018
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Punjab Agricultural University, Ludhiana
Abstract
Forty rhizobacterial isolates were evaluated for their PGP traits at 30˚and 40°C however, it was found that rhizobacteria were better acclimatized to 30°C as compared to 40˚C. 16S rDNA sequencing that two most potent isolates belonged to genera Enterobacter and Pseudomonas. IAA production at 30°C ranging from 9.6-38.8μg/ml decreased to 5.08- 29.01μg/ml at 40°C. IAA production was confirmed by HPLC analysis by MO1, MO32 and MO33 (16.1, 9.4 and 14.8 μg/ml respectively). The isolates were potent P and Zn solubilizers with P-solubilisation index ranging from 6-48mm and Zn solubilisation index ranging from 0.5 – 46 mm at 30°C. Surprisingly, the P and Zn solubilisation index at 40°C was at par with index range at 30 °C with MO1 and MO33 showing highest rate of P (48 and 48.5 mm) and Zn (46.6 and 44.5 mm) solubilisation. The gibberellic acid production ranged from 6-150μg/ml at 30°C and 3-90μg/ml at 40°C with MO1 (150 μg/ml) being the highest gibberellic acid producer. Isolates MO1, MO32 and MO33 were HCN and ammonia producers as well. The biocidal effect of the rhizobacterial allelochemicals against F.oxysporum and R.solani was studied using the standard techniques and it was established by the SEM studies. MO1, MO32 and MO33 proved to be strong antagonistic agents bringing about substantial inhibition of the phytopathogens (22.2 – 33.3%). The study carried out showed that isolates MO1, MO32 and MO33 exhibited growth and functionality traits both at 30˚ and 40˚C which were at par, hence, enabled their selection for field trials. The field experiment conducted revealed that co-inoculation of Rhizobium and MO33 proved to be the most efficient, resulting in the improvement of both symbiotic traits viz nodule number per plant (71), nodule dry weight (21.2 mg/plant), root (1.84 g/plant) and shoot (13.10 g/plant) dry weight and the yield (1174 kg/ha) of mung bean (ML2056) as compared to the control or Rhizobium treatment alone.
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