Evaluation of methylotrophs for plant growth promotion of mungbean (Vigna radiata (L.) Wilczek) and urdbean (Vigna mungo (L.) hepper)
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Date
2017
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CCSHAU
Abstract
Mungbean and Urdbean are two important pulses grown in India and they play an important
role in human nutrition. Methylotrophic bacteria exert several beneficial effects on host plant such as
stimulation of plant growth, nitrogen fixation and induction of resistance to plant pathogen. The use of
methylotrophs offers an attractive way to replace chemical fertilizers, pesticides and supplements. In
the present study, samples were collected from farm area of pulses section, Genetics and Plant
Breeding, COA, CCS HAU, Hisar in summer and kharif season to isolate the methylotrophs. In total,
60 methylotrophs were isolated using ammonium mineral salt medium. After isolation, all the
methylotrophic isolates were characterized for plant growth promoting traits: Indole acetic acid
production, phosphate solubilization, siderophore production, ACC utilization, temperature tolerance
(up to 450C) and salt (NaCl) tolerance (up to 5%). The majority of the methylotrophic isolates were
found to be IAA producers, though the production varied in the range of 01.09-29.99μg/ml and the
isolate MP12 produced maximum IAA (29.99 μg/ml) after 5 days incubation at 300C.P-solubilization
index (P-S.I.) varied from 0.60 to 2.96 after four days of incubation at 30ºC and maximum P-SI was
recorded in the isolate PP1(2.96). Siderophore production was detected by CAS (Chrome azurol S)
assay and it was observed that out of 60 isolates only 9 methylotrophic isolates were siderophore
producers. Overall 18% of methylotrophic isolates showed significant ACC utilization on minimal
medium plates. Four promising methylotrophic isolates, namely MP12, MP15, UP4 and PP1 which
showed maximum number of plant growth promoting traits were selected for plant growth evaluation
of mungbean and urdbean under pot house conditions. Among various treatments, coinoculation of
methylotrophic isolate MP12 along withRhizobium (MB703) and phosphate solubiliser (P36) was the
best treatment with respect to nodulation, plant growth and yield attributes under pot house as well as
field conditions. On the basis of morphological, biochemical characterization and 16S rDNA
sequencing isolate MP12, PP1 and UP4 were identified to be Methylobacterium oryzae UALW_217,
Ochrobactrum intermedium UALW_217 and Microbacterium ginsengisoli UALW_217.
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