DIVERSITY AND FUNCTIONS OF PHOSPHATE SOLUBILIZING RHIZOBACTERIA ASSOCIATED WITH APPLE SEEDLINGS
KrishiKosh
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Title |
DIVERSITY AND FUNCTIONS OF PHOSPHATE SOLUBILIZING RHIZOBACTERIA ASSOCIATED WITH APPLE SEEDLINGS
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Creator |
MEHTA, PREETI
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Contributor |
SHIRKOT, C.K.
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Subject |
bacteria, inorganic acid salts, planting, vegetative propagation, biological development, productivity, sampling, acidity, growth promoters, apples
apple, bacteria for increasing plant yields. |
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Description |
ABSTRACT The ability of a few soil microorganisms to convert insoluble forms of phosphorus to an accessible form is an important trait in plant growth-promoting bacteria for increasing plant yields. Little is known about the composition of phosphate solubilizing bacterial (PSB) diversity associated with rhizosphere of apple trees. Therefore, the objective of the present study was to investigate the diversity of PSB population associated with rhizosphere of soil and roots of apple and characterize them for multifarious plant growth promoting traits and to test the hypothesis, whether root exudates of apple trees exert a selective pressure on the proliferation of similar or different phosphate solubilizing plant growth promoting rhizobacterial population. Two hundred and six phosphate solubilizing bacteria were isolated by using culture dependent procedure from rhizosphere soil and endorhizosphere of apple trees of four locations viz., Chamba, Shimla, Kinnaur and Kullu of Himachal Pradesh. All the PSB isolates were screened for plant growth promoting traits (PGPT), including IAA production, siderophore, HCN, chitinase synthesis ability and antifungal activity against D. necatrix. IAA production was detected in 50 isolates (24.2%), siderophore synthesis in 53 isolates (25.7%), HCN in 40 isolates (19.4%), chitinase synthesis ability in 61 isolates (29.6%) and percent growth inhibition against D. necatrix in 61 isolates (29.6%). The diversity index (Shannnon-Weaver index) revealed that PGPT-possessing PSBs in rhizosphere soil were more diverse than root endosphere. Eighty five of total 206 PSB isolates possessed one or more than one plant growth promoting traits, hence these 85 PGPT- possessing PSBs were selected further for RAPD analysis. After RAPD- PCR analysis with primer RBa-4, 85 PSBs were divided in to five major groups. Sixteen representative PSB isolates from RAPD groups (3, 2, 8, 1, 2 isolates of Ist, 2nd, 3rd, 4th and 5th group, respectively.) were identified further by 16S rRNA analysis. The 16S rRNA analysis identified 16 PSBs as Bacillus subtilis, B. licheniformis, B. pumilus, B. altitudinis, B. methylotrophicus and B. firmus. Among 206 PSBs, a highly efficient P-solubilizing isolate was selected and presumptively identified as Bacillus subtilis CB8A. The isolate solubilized tri-calcium phosphate and produced substantial amount of soluble phosphorus (823 mg/l) in Pikovskaya’s (PVK) broth and exhibited the production of IAA (16.2 μg/ml), siderophore (85.21%) and growth inhibition against D. necatrix (56.67%). P- solubilization of B. subtilis CB8A was inversely correlated with pH (r = – 0.78) and positively correlated siderophore production (r = 0.81), IAA (r = 0.58) and antifungal antibiotic activity against D. necatrix (r = 0.63). Gluconic acid (1.43%) and citric acid (0.67%) were detected as the major organic acids with small percentages of 2- ketogluconic acid (0.34%), formic acid (0.15%), oxalic acid (0.10%) and fumaric acid (0.03%) during TCP solubilization by the B. subtilis CB8A. P- solubilization and nitrogen fixing abilities of the isolate CB8A were confirmed by amplification of gdh and nifH genes. Thus, the ability of performing multifarious plant growth promoting activities in tandem suggest B. subtilis CB8A a novel PSB isolate for plant growth promotion and has significance to develop a costeffective ecofriendly multifunctional biofertilizer for use in apple orchards, the most important cash crop in Himachal Pradesh. |
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Date |
2016-06-23T14:49:05Z
2016-06-23T14:49:05Z 2012 |
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Type |
Thesis
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Identifier |
http://krishikosh.egranth.ac.in/handle/1/67869
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Language |
en
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Format |
application/pdf
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