Indole acetic acid production from pseudomonas fluorescens and its effect on root elongation of vigna radiata

Rhizospheric soil samples were collected from in different garden samples in Chidambaram. Among 7 isolates 1 strain was developed deep pink colour, which was selected as potential strain for further study. It was showed highest OD value at 530nm. It was identified as Pseudomonas fluorescens was found to produce IAA 2.5µg/ml. The maximum production of 3.7µg/ml was observed at pH 7 and minimum at pH 10 (1.9µg/ml). Maximum production of 3.3µg/ml was observed at 30°C which seemed to be the most favorable and minimum was observed at 40°C (1.5µg/ml). The effect of Nacl on the IAA production maximum 2.9µg/ml (0.2%) and minimum 0.8µg/ml (1.0%), different carbon sources maximum 3.9µg/ml in glucose and minimum fructose (2.3µg/ml), different nitrogen sources on IAA maximum 3.8µg/ml in yeast extract and minimum potassium nitrate were observed. Influence of tryptophan on the IAA production maximum 3.5µg/ml at 1.0% and minimum at 3.0% (2.1µg/ml) were noted. Pseudomonas fluorescens in mass scale with optimized parameters, produced the highest IAA at 8th day of incubation (4.6µg/ml) On further incubation the amount of IAA was found to be reduced. The TLC done for the crude IAA compound showed a Rf-value of 0.88. The purified and standard showed same Rf values. The seed germination test revealed 100% germination in IAA treated seeds and only 76% germination was observed in control seeds. In the present observation the average Vigna radiata root length developed in 50 seedlings was estimated in both IAA treated and control seedlings. The average root length was 42mm in IAA treated seedlings where as it was only 28mm in control seedlings.