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Pak. J. Bot., 45(6): 1955-1962, 2013.

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SALT-TOLERANT PGPR STRAIN PLANOCOCCUS RIFIETOENSIS PROMOTES  THE GROWTH AND YIELD OF WHEAT (TRITICUM AESTIVUM L.) CULTIVATED IN SALINE SOIL

LUBNA RAJPUT¹, ASMA IMRAN¹, FATHIA MUBEEN¹ AND FAUZIA Y. HAFEEZ^{1, 2*}

Abstract: Rhizobacteria improve plant growth employing a variety of growth promoting mechanisms including nutrient up-take, root growth, proliferation and biocontrol activities. Present study characterizes a salt-tolerant, IAA producing, phosphate solubilizing bacterial strain SAL-15 containing ACC-deaminase activity and evaluates its potential for enhancing growth and yield of wheat (Triticum aestivum L. var. TJ-83) under salinity stress In vitro and In vivo. The bacterium was identified as Planococcus rifietoensis based on 16S rRNA sequence analysis. It was catalase/oxidase positive, Gram-positive, rod-shaped, orange colored alkaliphilic bacterium, able to grow up to 65 g/L NaCl salinity in the medium. The bacterium produced 264.2 µg/mL IAA in the tryptophan-supplemented medium, released 16.7 µg/mL phosphorus from inorganic-tricalcium phosphate in the Pikoviskaya’s medium and utilized ACC as nitrogen source at 100 as well as 300 mM NaCl concentration in respective media. Salinity severely reduced various growth and yield parameters of wheat (up to 60%) both in pot and field experiments. However, SAL-15 inoculation enhanced growth and yield by alleviating the toxic effects of salinity. Inoculation of SAL-15 resulted in 37% increase in overall plant growth under salt stress, 63% in the presence of inorganic tri-calcium phosphate and >60% in the presence of ACC.  Based on the results, we conclude that bacterial isolate SAL-15 can be used as potent bacterial inoculum for yield improvement of wheat under salinity stress.

¹National Institute for Biotechnology and Genetic Engineering (NIBGE), P.O. Box 577-Jhang Road, 38000 Faisalabad, Pakistan

²Department of Biosciences, COMSATS Institute of Information Technology, Chak Shahzad Campus, Park Road, Islamabad, Pakistan

^*Corresponding author e-mail: fauzia_y@yahoo.com