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RHIZOBACTERIA CONTAINING ACC-DEAMINASE FOR IMPROVING GROWTH AND YIELD OF WHEAT UNDER FERTILIZED CONDITIONS

M. NAVEED, Z.A. ZAHIR*, M. KHALID, H.N. ASGHAR, M.J. AKHTAR AND M. ARSHAD

Abstract: Certain plant growth promoting rhizobacteria (PGPR) regulate the production of ethylene in plants and promote root elongation by hydrolyzing 1-aminocyclopropane-1-carboxylic acid, ACC (the immediate precursor of ethylene), through the action of ACC-deaminase. Rhizobacteria containing ACC-deaminase were isolated and screened for their growth promoting activity in wheat (Triticum aestivum L.) under axenic conditions. Three promising isolates (S5, S7 and S9) were selected on the basis of ACC-deaminase activity and growth promotion under axenic conditions. The performance of these selected PGPR isolates was evaluated with 50 and 75% of recommended (NPK: 120-100-60 kg ha-1) chemical fertilizers for promoting growth and yield of wheat. Inoculated seeds were sown in the field, fertilized with NPK according to the treatments. All the isolates exhibited a significant increase in all the yield-contributing parameters at 50 and 75% of recommended chemical fertilizers compared with untreated control. It was observed that PGPR isolate S7, along with 75% of recommended chemical fertilizers, showed statistically similar results with recommended chemical fertilizers alone and it increased plant height, number of tillers meter-2, spike length, number of spikelets spike-1, total biomass, grain yield and 1000-grain weight by 11, 63, 22, 28, 98, 96 and 31%, respectively, over untreated control. Other attributes like NPK uptake were also increased (141, 160 and 174%, respectively) over untreated control. The growth promoting activity exhibited by the rhizobacterial isolate S7 might be due to its high In vitro IAA production, chitinase activity, P-solubilition and more intensive root colonization, besides ACC-deaminase activity. Results suggested that plant growth promoting rhizobacteria containing ACC-deaminase activity could be used as successful inoculant for improving wheat yield by reducing dependence on chemical fertilizers and saving ~ 25% of recommended chemical fertilizers. However, some other characteristics of the rhizobacteria such as root colonization ability and chitinase activity could also be used as an effective tool for selection/screening of efficient PGPR strains.

Institute of Soil & Environmental Sciences, University of Agriculture Faisalabad-38040, Pakistan.

Corresponding author: E-mail: zazahir@yahoo.com Phone: 92 41 920 1092, Fax: 92 41 920 1221