CHARACTERIZATION OF MULTI-TRAIT PLANT GROWTH PROMOTING RHIZOBACTERIA AND EVALUATING THEIR POTENTIAL AS BIOINOCULANT FOR ENHANCED GROWTH AND YIELD OF TOMATO
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Date
2016
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ABSTRACT
The present investigation entitled “Characterization of multi-trait plant growth promoting rhizobacteria and evaluating their potential as bioinoculant for enhanced growth and yield of tomato” was carried out in the Department of Basic Sciences, Dr Y. S. Parmar University of Horticulture & Forestry Nauni, Solan (HP) during 2013-2015. The application of PGPR based bio-inoculants on vegetable crops production is gaining importance as it is a widely accepted fact that PGPR play a key role in plant health and nutrition. Keeping this in view, present study aimed at characterization of bacterial isolates from different crops rhizosphere for multiple plant growth promoting traits and their co-inoculation efficiency along with variable doses of chemical fertilizers for enhanced growth and yield of tomato. A total of 20 bacterial isolates from rhizosphere of different crops were screened for multifarious plant growth promoting activities viz., production of IAA, Psolubilization, siderophore production, growth on nitrogen free medium, in vitro antibiosis against Fusarium oxysporum f.sp. lycopersici (FOL), Phytophthora capsici, Pythium aphanidermatum and lytic enzymes activities. Six most efficient PGPR (S21, S25, B6, A10, MK5 and PM9) showing significant PGP traits, were identified by 16S rDNA sequencing and were identified as B. subtilis T1, B. subtilis CKTR, B. licheniformis CKA1, B. safensis A10, B. pumilus MK5 and B. subtilis PM9 respectively. Sole application of selected six Bacillus strains under field conditions resulted in significant increase in various plant growth and yield parameters over control. B. subtilis T1 resulted in highest increase in tomato yield (79.81%) over untreated control. The most efficient Bacillus strains, B. subtilis T1 and B. licheniformis CKA1 showed remarkable tricalcium phosphate solubilization under in vitro and in planta conditions and were further evaluated under field conditions along with variable doses of chemical fertilizers for enhanced growth and yield of tomato. Field studies revealed that conjoint application of 75% NPK + B. subtilis T1 increased tomato yield by 38.23% over recommended dose of chemical fertilizers besides saving 25 per cent chemical fertilizers. Evaluation of biocontrol potential under net house conditions revealed that liquid based culture of B. subtilis T1 reduced the disease incidence of FOL by 86.67% and B. subtilis CKTR achieved a biocontrol efficacy of 83.33% against P. capsici. Detection of various lipopeptides like iturin, fengycin and surfactin in strains T1 and CKTR explains the possible mechanism of biocontrol by these strains. Diversity analysis of culturable bacterial population associated with tomato rhizosphere revealed significant variations in viable bacterial population and number of morphotypes in the rhizosphere and roots of tomato collected from UHF-Nauni, Solan and Dharja, Solan respectively. Genetic diversity study on the basis of ARDRA analysis divided all the isolates into 9 phylotypes at 80% similarity level. The representative PGPR from each phylotype were identified by 16S rDNA sequencing and were belonged to different species of genus Bacillus viz., tequilensis, amyloliquifaciens, subtilis, rhizosphaerae, methylotrophicus, axerguiensis, sonorensis, flexus and two isolates of genus Brevibacterium were obtained. Overall, present study conclude that, in view of environmental pollution due to excessive use of agricultural chemicals and high cost of the production of chemical fertilizers, B. subtilis T1 may well be used to achieve more sustainable and environment friendly tomato production under mid hill regions of Himachal Pradesh
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bacteria, planting, biological development, vegetative propagation, vegetables, inorganic acid salts, productivity, growth promoters, selection, enzymes, Tomatoes,rhizobacteria