Morphological and bio chemical characterization of Winged bean Rhizobium and its impact as seed Inoculant either singly or Combinedly with PGPR towards Yield Attributing Characters and Yield of Winged Bean (Psophocarpus tetragonolobus)”
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Date
2018
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Dr. Rajendra Prasad Central Agricultural University, Pusa, Samastipur
Abstract
A laboratory investigation for morphological and bio-chemical characterization
and physiological properties of winged bean Rhizobium with a purified culture; and a
field experiment consisting of four seed-inoculation treatments [No inoculation,
Rhizobium, PGPR(Bacillus) and Rhizobium+PGPR(Bacillus)] and three nitrogen levels
[0, 20 and 40 kg ha-1] in RBD (factorial) with three replications for evaluation of two
winged bean germplasm IC-17002 and DLN-9, during crop season in the year 2014-15
and with better-performing IC-17002 in 2015-16 to find out impact of the Rhizobium as
seed inoculant alone or in combinedly with PGPR on yield attributes and yield of
winged bean were conducted at Tirhut College of Agriculture, Dholi Farm of RPCAU,
Pusa (Bihar).
The pure-culture of winged bean Rhizobium isolate was Gram-negative
rod-shaped with a dimension of 0.59 μm x 1.81μm. The Rhizobium tested vis-à-vis (pea,
gram, lentil and moong-rhizobia) showed a wide diversity in tolerance for its growth at
different pH values, though neutral pH being the optimum. The winged bean-Rhizobium
isolate produced 64.6 μg mL-1 of IAA at 72h of incubation with antibiotic-resistance
and carbon-utilization test, the Rhizobium isolate was found to be resistant to
vancomycin (30μg) and utilized a wider group of carbon sources than other rhizobia.
The Fatty-Acid-Methyl-Ester (FAME) profiling confirmed that it belonged to
Rhizobium-miscellany group.
Seed inoculation and nitrogen levels greatly influenced nodule-parameters,
nitrogenase activity and yield attributes, value of which were the highest with the
combined inoculation of Rhizobium+PGPR (Bacillus), followed by seed inoculation of
Rhizobium alone, and differed significantly among themselves at both 60 and 120 days
after sowing (DAS). Nitrogen application @ 20 kg ha-1 recorded significantly higher
nodule parameters over the control. The inoculation x nitrogen interaction effect was
found to be significant with respect to nodule parameters. The combined inoculation of
Rhizobium+PGPR (Bacillus) at 20 kg N ha-1 appeared significantly superior to other
treatment combinations. S, Fe and Mo in the nodule recorded higher at 60 DAS than at
120 DAS. Rhizobium inoculation alone caused higher S and Mo content in nodule,
whereas combined application of Rhizobium and PGPR recorded the highest Fe content
at both growth stages. Nitrogen application @ 20 kg ha-1 increased Fe content
significantly over no-nitrogen application at 120 DAS. The highest nitrogen content in
pod was noted by combined inoculation of Rhizobium and PGPR treatment, followed by
Rhizobium alone. Nitrogen @ 20 kg ha-1 was found to be superior to the higher level of
N application. The combined inoculation of Rhizobium and PGPR at 20 kg N ha-1
proved better than the other treatments. The treatments recorded greater N and P content
of winged bean plant at 60, 120 DAS and at harvest. In seed, Rhizobium and PGPR
inoculation in combination recorded more N content than other treatments and was
found to be at par with Rhizobium inoculation alone. Nitrogen application @ 20 kg ha-1
recorded higher N, P and K in seed of winged bean in first year only. Protein content in
green edible pod, seed and tuber was significantly increased by combined inoculation of
Rhizobium and PGPR over the control and was at par with the treatment of Rhizobium
inoculation alone, whereas basal nitrogen @ 20 kg ha-1 favoured more protein content
than higher level of nitrogen. After harvest of winged bean, the highest available soilnitrogen
build-up was recorded with the treatment of Rhizobium inoculation alone.
Seed-oil content (33.76 %) recorded the highest in the treatment with seed inoculation
of PGPR at zero nitrogen application. The study proved the multiple-utilitarian potential
of winged bean including its role in soil fertility improvement which was best with seedinoculation
of Rhizobium-miscellany and PGPR either alone or in combination with
basal dose of 20 kg N ha-1.