CHARACTERIZATION OF DROUGHT TOLERANT PLANT GROWTH PROMOTING RHIZOBACTERIA AND THEIR EVALUATION ON STRAWBERRY (Fragaria × ananassa Duch.)
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Date
2022-11
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UHF,NAUNI
Abstract
ABSTRACT
Drought is the prime abiotic stress that rigorously influence plant growth, yield and quality attributes of the crops.
For sustainable agriculture, drought resistant plant growth promoting rhizobacteria are new encouraging prospects, which are
inexpensive and have no side effects as those of synthetic fertilizers. The present investigation was carried by isolation and
enumeration of soil samples from during rainfed areas of six sites of three districts of Himachal Pradesh. The maximum
bacterial count was recorded as 5.70×106 log cfu/g in Dhaula Kuan site of Sirmaur district. A total of 111 bacterial isolates
were isolated from the collected soil samples. The isolates were screened for osmotic stress (-0.05MPa, -0.15MPa,-0.30MPa,
-0.49MPa, -0.73MPa) attained with PEG concertation. The 41 isolates were selected after stress of -0.73 MPa with PEG 25
percent concentration. These 41 isolates were screened for ACC deaminase, EPS production, Proline, Total and free amino
acids and 33 isolates were selected as drought tolerant isolates. These 33 were then screened for growth promoting traits.
Among these 33 isolates 84.8 per cent isolates were P- solubilizers, 63.6 per cent were N-fixer, 93.9 per cent were Ammonia
producers, 57.6 per cent were HCN producers and 60.6 per cent were siderophore producers. Out of 33 isolates quantitative
estimation of 27 isolates selected and further tested for quantitative estimation of growth promoting traits The isolates SDK8
and SBU4 showed maximum potential for P- solubilization i.e., 92.86 μg/ml and 94.57 μg/ml, siderophore production of
63.12 %SU and 52.14 %SU, IAA production of 72.64 μg/ml and 74.63 μg/ml. The isolates SDK8 and SBU4 were able to
grow maximum at incubation period of 48 hours, pH 7.0 and temperature of 35°C. These two isolates were tested further for
their growth promoting and drought tolerating abilities in strawberry. The interactive effect of selected PGPR in strawberry
plants under water stress (3,5,7 and 10 days) was performed. The plants were able to tolerate water stress upto 3,5,7 days
only. Moreover, the significant increase in vegetative growth parameters with T1(PGPR1) and T2(PGPR2) alone and in
combination with consortium T3(PGPR1+PGPR2) was recorded. The consortia recorded highest increase in plant height,
number of leaves, leaf area, number of runners, shoot fresh and dry weight, root length, root fresh and dry weight and over
uninoculated control. Treatment T3 also showed significant increase in biochemical constituents (increased level of relative
leaf water content, total chlorophyll, protein and decreased level of phenol, antioxidant) in strawberry leaves. Interactive
effect of water stress and recovery with selected Plant Growth Promoting Rhizobacteria (PGPR) was observed on the
vegetative and fruiting characteristics of strawberry. The observations were recorded after 3, 5 and 7 days interval of water
stress and recovery. The plants were statistically at par with control with PGPR after water stress for 3, 5 and 7 days and
recovery. The application of PGPR showed significant increase in vegetative growth parameters with T1(PGPR1) and
T2(PGPR2) alone and was highest with treatment of consortia T3(PGPR1+PGPR2) over uninoculated control. It was also
found that fruit yield parameters viz. number of flowers (19.33), fruit weight (8.59g) and fruit quality the treatment viz. total
soluble sugars (11.09%), titrable acidity (0.54), anthocyanin (45.89mg/100g), ascorbic acid content (42.92 mg/100g), sugar
content showed maximum increase with treatment of consortia T3(PGPR1+PGPR2) compared to uninoculated control.
Thus, outcome of this comparative investigation indicates that Pseudomonas fluorescens (SBU4) and Pseudomonas glycinae
(SDK8) are drought tolerant and possess the multiple beneficial properties of growth promotion. Therefore, these two
isolates could be utilized as bioinoculant in strawberry to improve yield and quality even under short term drought stress
conditions.