STUDIES ON PLANT GROWTH PROMOTING RHIZOBACTERIA ASSOCIATED WITH SEABUCKTHORN (Hippophae rhamnoides)
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Date
2013
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Abstract
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 medicinal plant.
Therefore, the present study was aimed to explore the diversity of P-solubilizing bacterial communities colonizing
the rhizosphere soil and roots of medicinal plant seabuckthorn grown in natural conditions for the plant growth
promoting activity towards the development of microbial inoculants for different crops grown in normal and stressed
region. One hundred and six phosphate solubilizing bacteria were isolated by using culture dependent procedure
from rhizosphere soil and endorhizosphere of seabuckthorn of two locations viz., Lahaul & Spiti of Himachal
Pradesh. All the PSB isolates were screened for plant growth promoting traits (PGPT), including IAA production,
siderophore, HCN, ability to grow on nitrogen free medium and antifungal activity. IAA production was detected in
74.52%, siderophore synthesis in 26.42%, HCN in 43.39%, nitrogen fixing ability in 65.85% isolates. Inhibition
against A. solani was detected in 46.22% isolates and 25.47% of isolates had ability to inhibit the growth F.
oxysporum. Out of total P-solubilizing bacterial isolates, fourteen isolates were selected on the basis of dendrogram
derived from similarity coefficient among PGP traits. Isolates LU45* accumulate maximum phosphorus 239.24
μg/ml among selected 14 isolates along with other PGP traits (IAA, Siderophore, HCN, antifungal and lytic enzyme
activity), therefore, selected for identification and characterization of different culture conditions for in vitro TCP
solubilization. However, isolate T2R was morphologically different among all other isolates with a unique ability to
produce red pigment, showed maximum PSI (5.0) and therefore, isolate T2R was also characterized phenotypically,
biochemically and molecular based characterization. For net house studies, six isolates with PGPT were evaluated
for their effect on early growth of tomato seedlings. Isolate T76* showed maximum per cent increase in root length,
shoot length, root & shoot dry weight and vigour index and was also selected for identification. On the basis of
results obtained from 16S rDNA analysis, isolate LU45*, T2R, T76* was identified as Bacillus subtilis CKS1, Serratia
sp. AS2, Bacillus sp. AS3 respectively. Present study first time reported Serratia sp. from rhizosphere of
seabuckthorn. Thus, the ability of performing multifarious plant growth promoting activities in tandem suggest PSB
isolates for plant growth promotion and has significance to develop a cost-effective ecofriendly multifunctional
biofertilizer.
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Keywords
oilseed cakes, biological phenomena, proteins, oilseeds, biological development, research methods, animal husbandry, aromatic compounds, animal products, soybeans, seabuckthorn ,rhizosphere soil ,plant growth