Phosphate solubilization potential of fluorescent Pseudomonas spp. isolated from diverse agro-ecosystems of india

Abstract

Phosphorus is one of the major nutrients limiting plant growth. The solubilization of P in the rhizosphere is the most common mode of action implicated in PGPR that increase nutrient availability to host plants. About 75 isolates of Pseudomonas spp. were obtained by plating the rhizosphere soil samples from different agro-ecosystem locations of India. All the isolates were initially screened for tri calcium phosphate (TCP) solubilization under in vitro conditions on Pikovskaya's agar medium and followed by in liquid medium. A total of 10 promising isolates were further checked for their ability to solubilize rock phosphate in liquid medium. Results showed that the amount of P solubilized by different isolates ranged between 2.11 and 15.19 mg L-1. Highest P solubilization was observed with strain P17 (15.19 mg L-1) that showed spent medium pH of 3.36. The fall in pH corresponded with the solubilization of insoluble P. Maximum rock phosphate solubilization of 12.9 mg L-1 was observed with P29 followed by P17 which solubilized 12 mg L-1. The P29 which showed highest rock phosphate solubilization recorded lowest pH of 3.7. From this study it is evident that, most of the strains solubilizing rock phosphate were isolated from semi-arid, deep alfisols of Deccan Plateau agro-ecological sub region of India suggesting that these strains are potential phosphate solubilizers. And strains like PI7 and P29 could be viable, cost-effective alternatives of chemical fertilizers for management of plant nutrition. © 2014 Academic Journals Inc.