Rhizosphere colonization of phosphate solubilizing bacteria and their effect on chickpea (Cicer arietinum L.) growth and nutrient uptake
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Date
2005
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CCSHAU
Abstract
Seventy six isolates of phosphate solubilizing bacteria from rhizosphere
of chickpea were evaluated for solubilization of tricalcium phosphate (TCP)
and Udaipur rock phosphate (URP). Solubilization efficiency (PSE) of various
isolates varied from 6.0 to 118.3 per cent on solid medium. Sixty nine isolates
showed < 50 per cent PSE and only 2 isolates showed PSE more than 100 per
cent. P solubilization by all the isolates varied from 22.7 to 247.7 g/ml.
Seven isolate showed >200 g/ml solubilization in liquid medium. Phosphate
from rock phosphate was poorly solubilized which varied from 0.001 to 0.258
g/ml. No relationship between P solubilization and change in pH was
observed. Only fifteen isolates have complementary antibiotic resistance with
donor strain of E. coli. Morphological and biochemical characteristics of
selected isolates based on P solubilization efficiency (18C, 42C, 43C and 76C)
showed that they belong to genus Pseudomonas. The various transconjugants
showed -galactosidase activity varying from 0.96 to 2.02 Miller’s Unit and
showed blue colour on X-gal medium plates. The transconjugants (42CT and
76CT) were able to survive in chickpea rhizosphere under pot house
conditions, which appeared as blue colonies on X-gal plates with a population
of ~103/gram soil, upto 120 DAS. The PSB and their transconjugants showed
an increase in dry shoot weight and nutrients uptake by chickpea. Dry matter
yield of 61.81, 82.91 and 110.75 g/pot was recorded by the application of 30
kg SSP with PSB at 60, 90 and 120 DAS respectively. N and P uptake
increased with the inoculation of PSB and their transconjugants. Significantly
higher N uptake 31.54 and 66.31 per cent was recorded by the inoculation of
SSP with 42C and SSP (60 kg/ha) at 90 and 120 DAS, respectively than
control. At 90 and 120 DAS, maximum P uptake 92.56 and 114.0 per cent,
respectively, was recorded by the inoculation of SSP with 42C than control.