Evaluation of phosphate solubilizing bacterial strains/mutants with improved phosphate solubilization and their effect on mustard crop
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Date
2005
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CCSHAU
Abstract
Sixty eight isolates of phosphate solubilizing bacteria (PSB)
from rhizosphere of mustard grown in different region of Haryana showed a
large variation in P-solubilization on solid as well as in liquid media. Most of
isolates fell in <50% class of P-solubilization while in liquid media in
50-100μg/ml. No correlation was recorded between P-solubilization on solid
media and liquid media. The selected isolates 15M, 22M and 25M showed
P-solubilization 273.0 μg/ml, 301.0 g/ml, and 276.0 g/ml in liquid PVK,
while in NBRIP 288.0 g/ml, 314.0 g/ml and 286.0 g/ml, and were used
for subsequent studies. These isolates were identified as Pseudomonas sp.
based on morphological and biochemical characteristic. The selected
isolates were mutagenesied with NTG (50g/ml) for high P-solubilization.
One hundered forty four mutants were selected based on killing rate
between 70-80%. These mutants were checked for P- solubilization in solid
and liquid PVK and NBRIP medium. The PSE of 15M mutants on solid
medium varied from18.2-98.6% on PVK and from 14.1-96.2% on NBRIP
media. While PSE of 22M mutants varied from 12.4-98.1% on PVK and from
18.4-100.2% on NBRIP media. The PSE mutant 25M varied from 12.1-77.1%
on PVK and 10.2-85.4% on NBRIP solid media. The pH of 15M mutants
varied from 3.6-6.0 in PVK in NBRIP it varied from 3.4-5.8, while pH of 22M
mutant in PVK varied from 2.9-5.8 in PVK, in NBRIP it ranged from 2.1-5.6.
The pH of 25M mutants varied from 2.5-5.9 in PVK and 2.3-5.8 in NBRIP.
The 15M mutants showed P-solubilization between 177.1-324.1 g/ml in
liquid PVK, while 176.4-336.4 g/ml in liquid NBRIP. 22M mutants showed
P-solubilization between 182.2-362.2 g/ml in liquid PVK from
201.3-380.1g/ml in NBRIP. 25M showed P-solubilization between
167.4-351.9 g/ml in liquid PVK, while 175.8-364.5 g/ml in NBRIP.
Strains (15M, 22M and 25M) and mutants (15M2, 15M6, 22M28, 22M29,
25M11, 25M30) were selected on basis of P-solubilization for pot culture
experiment on mustard cv. RH-30.
Total bacterial count in rhizosphere increased with URP at 30
and 45 DAS, while decrease was observed at 60 DAS. The number of these
bacteria improved with seed inoculation and was more with URP. The
number varied from 10-78, 27-91, and 13-37 at 30, 45, and 60 DAS
respectively. The maximum number was observed with 15M6 with URP
(50x105 cfu/g) followed by 22M28 with URP (78x105 cfu/g) at 30 DAS. At
45 DAS the maximum number was observed with 22M28 with URP (91 x
105 cfu/g) followed by 15MP with URP (85 x 105 cfu/g) and at 60 DASnumber was observed with 22M28 with URP (37 x 105 cfu/g) followed by
22M29 with URP (27 x 105 cfu/g).
The PSB count in the rhizosphere varied from 1-24, 2-20 and
1-11 at 30, 45 and 60 DAS, respectively. The maximum number was
observed with 22M28 (24 x 103 cfu/g) followed by 15M6 (19 x 103 cfu/g) at
30 DAS. At 45 DAS the maximum number was observed with 22M29 (20 x
103 cfu/g) followed by 22M29 with URP (19 x 103 cfu/g). The mustard
biomass was more with SSP and with URP compared to the control at 30, 45
and 60 DAS. There was increase at 30 and 45 DAS but a 60 DAS with SSP
marginal increase was observed. Almost all the mutants with URP showed
increase in biomass except 25M30. The maximum biomass was observed
with 22M28 (0.682 g/plant) followed by 22M29 (0.456 g/plant) at 30 DAS
while at 45 DAS in case of 22M28 with URP (2.114 g/plant) followed by
22M29 (1.651 g/plant). At 60 DAS the maximum plant dry biomass was
observed in 22M29 (3.161 g/plant) followed by 22M28 (2.927 g/plant).
Phosphate uptake was increased upto 21 and 11% with
application of SSP and URP at 30 DAS respectively but at 45 DAS increase
was 12% with SSP and 4% with URP. But at 60 DAS there was 53% increase
with SSP and 50% with URP. The maximum P-uptake was observed with
22M28 with URP (529%) followed by 22M29 is (429%). However, at 60 DAS
the maximum P-uptake was by 22M29 (31%) followed by 22M28 with URP
that was 308% it shows that mutants had significant effect on increase in
plant dry biomass and P-uptake under pot house conditions.