Diversity of Native Rhizosphere Pseudomonad of Jammu with Potential for Plant Growth Promoting Activity

Pseudomonas spp. from rhizosphere soils of different crops were isolated and characterized on the basis of production of antimicrobial and plant growth promoting compounds as well as biochemical indices. The isolates showed positive reactions for catalase production, indole production, phosphorus solubilization, arginine hydrolysis and gelatin liquefaction but negative for starch hydrolysis and urease activity. Assay of antimicrobial compounds production revealed that siderophore production was highest in isolate PS 1 (32.25 μg ml⁻¹). Isolates from PS 1 to PS 20 produced ferrate hydroxamate type of siderophores where as the siderophore production by the isolates from PS 21 to PS 30 may be of catecholate type. Growth promoting substances viz. Indole acetic acid (IAA) was highest in PS 7 isolate (583.63 μg ml⁻¹) whereas Gibberellic acid (GA) was maximum in PS 15 (652.07 μg ml⁻¹). Phosphorus solubilization estimated from broth cultures was maximum in PS 30 (358.25 μg ml⁻¹), respectively. Isolate Pseudomonas spp. (PS 10) was evaluated to determine its promoting effect on the germination of mustard seeds grown under in vitro conditions in bacterial suspension medium. The results showed that the seeds which were grown in bacterial suspension revealed on an average of 58.33 per cent germination. Thus, the isolates of P. fluorescens has promoting effect on the growth characteristics.