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POTENTIAL OF PLANT GROWTH PROMOTING RHIZOBACTERIA AND CHEMICAL FERTILIZERS ON SOIL ENZYMES AND PLANT GROWTH

ASIA NOSHEEN AND ASGHARI BANO^*

Abstract: The present investigation deals with the role of Plant Growth Promoting Rhizobacteria and chemical fertilizers alone or in combination on urease, invertase and phosphatase activities of rhizospheric soil and also on general impact on growth of safflower cvv. Thori and Saif-32. The PGPR (Azospirillum brasilense and Azotobacter vinelandii) were applied at 10⁶cells/mL as seed inoculation prior to sowing. Chemical fertilizers were applied at full (Urea 60 Kg ha^-1 and Diammonium phosphate (DAP) 30 Kg ha^-1), half (Urea 30 Kg ha^-1 and DAP 15 Kg ha^-1) and quarter doses (Urea 15 Kg ha^-1 and DAP 7.5 Kg ha^-1) during sowing. The chemical fertilizers and PGPR enhanced urease and invertase activities of soil. Presence of PGPR in combination with quarter and half doses of chemical fertilizers further augmented their effect on soil enzymes activities. The soil phosphatase activity was greater in Azospirillum and Azotobacter in combination with half dose of chemical fertilizers. Maximum increase in leaf melondialdehyde content was recorded in full dose of chemical fertilizers whereas coinoculation treatment exhibited significant reduction in cv. Thori. Half and quarter dose of chemical fertilizers increased the shoot length of safflower whereas maximum increase in leaf protein was recorded in Azotobacter in combination with full dose of chemical fertilizers. Root length was improved by Azospirillum and Azotobacter in combination with quarter dose of chemical fertilizers. Leaf area and chlorophyll contents were significantly improved by Azotobacter in combination with half dose of chemical fertilizers. It is inferred that PGPR can supplement 50 % chemical fertilizers for better plant growth and soil health.

Department of Plant Sciences, Quaid-i-Azam University, Islamabad, Pakistan

^*Corresponding author: banoasghari@gmail.com