Indole Acetic Acid (IAA) Mediated Plant Growth Promotion Activity of Fluorescent Pseudomonads and Bacillus spp.
Kahkashan Arzoo
Department of Plant Pathology, Bihar Agricultural University, Sabour, Bhagalpur, Bihar, India.
Rekha Balodi
ICAR National Research Centre for Integrated Pest Management, New Delhi, India.
Erayya *
Department of Plant Pathology, Bihar Agricultural University, Sabour, Bhagalpur, Bihar, India.
Kalmesh, M
Department of Entomology, Bihar Agricultural University, Sabour, Bhagalpur, Bihar, India.
J. Kumar
Department of Plant Pathology, G B Pant University of Agriculture and Technology, Pantnagar, UK.
*Author to whom correspondence should be addressed.
Abstract
This investigation was made to study the involvement of IAA in plant growth promotion and vigor of wheat plants induced with plant growth promoting rhizobacteria. Nineteen isolates of fluorescent pseudomonads and 11 isolates of Bacillus spp. were subjected to germination percentage and seedling vigor index test. These parameters were determined according to recommended methods by ISTA (1985). The IAA production from selected bacterial isolates, which were showing the potential function of plant growth promotion were further subjected to quantitative analysis using Salkowski’s reagent (2% of 0.5 M FeCl3 in 34% HClO4) for Colorimetric detection. The vigor index and plant growth were significantly increased in Pfa-65 (43.36%) followed by B-18 (42.58%), Pfa-77 (40.83%), B-24 (40.68), Pfa-37(38.82%) and B-38 (38.52). The maximum concentration of IAA was detected in the isolate B-24(36.66 µg/ml) followed by Pfa-65(36.16 µg/ml), B-18(35.98 µg/ml) and Pfa-77(35.72 µg/ml). A positive correlation was observed between concentration of IAA produced and germination percentage with PGPR treatments (correlation coefficient was 0.94). The correlation coefficient was 0.96 between IAA produced and percent increase in vigor index with the treatments. Our data suggests that IAA, a growth promoting hormone, might be the key factor to promote the plant growth directed by the rhizobacteria
Keywords: Bacillus spp, fluorescent pseudomonads, germination percentage, Indole-3-Acetic Acid (IAA), Plant Growth Promoting Rhizobacteria (PGPR), vigor index