Production of Indole Acetic Acid and Plant Growth Promotion by Rhizobacteria from a Less Studied Marine Ecosystem

M. Jayaprakashvel^1,3, V. Kiran Kumar², Jainul Abideen², Swarnakala¹, M. Venkatramani¹ and A. Jaffar Hussain^1,3

¹Department of Marine Biotechnology, AMET University (u/s 3 of UGC Act 1956) 135, East Coast Road, Kanathur, Chennai-603112, India ²Department of Environmental Sciences, Sri Venkateswara University Tirupati, Andhra Pradesh-517 502, India. ³Centre for Marine Bioprospecting, AMET University (u/s 3 of UGC Act 1956) 135, East Coast Road, Kanathur, Chennai-603112, India

DOI : http://dx.doi.org/10.13005/bbra/1408

ABSTRACT: Coastal sand dunes are one of the less explored marine ecosystems. The environmental conditions prevailing in these ecosystems make the microorganisms and other living forms more competent and may have good potential. So, bioprospecting of coastal sand dune microorganisms is a worthy one. In this paper, we report the ability of coastal sand dune rhizobacteria to produce indole acetic acid and their potential to increase the seedling growth of crop plants. A total of 47 rhizobacterial strains were isolated from 5 rhizosphere samples collected from the coastal sand dunes in Uthandi Beach, Chennai. Among the 47, 22 rhizobacteria were found to be fluorescent pseudomonads. Among 47, 7 were found to be gram positive and remaining were gram negative bacteria. 11 among these 47 rhizobacteria were found to produce plant growth hormone indole acetic acid (IAA) extra-cellularly. Quantitative tests resulted in short listing strains AMET9318, AMET9323 and AMET9345 as highest IAA producers. All these three IAA producing strains were demonstrated for their remarkable ability to increase seedling length and seedling weight of wheat, green gram, mustard, black gram and kidney bean through seedling growth chamber studies. Thus, the present study concludes the plant growth promotion potentials of coastal sand dune rhizobacteria which can be used as biofertilizers in coastal saline soils.

KEYWORDS: coastal sand dunes; rhizobacteria; indole acetic acid; plant growth promotion; Biofertilizers

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