Plant growth promotion of Vigna unguiculata in arid sandy soil using bacterial species from coastal sand dune

Abstract

The coastal sand dune (CSD) ecosystem exhibits various stresses where organisms are exposed to dry, nutrient-deficient, intense UV rays, tidal effects, fluctuating pH, temperature and salinity conditions. Hence, it is considered unsuitable for agricultural practices. Despite this, microorganisms inhabiting CSD not only survive these but also support plant growth. From 13 different sand samples of CSD of Goa-India, 250 isolates were obtained on 7 distinct media. These isolates were screened for various plant growth-promoting (PGP) attributes in vitro. Five bacterial isolates exhibiting maximum PGP factors were selected for further screening for ACC deaminase production, antifungal activity and hydrolytic enzyme production. These isolates were subjected to the production of Indole acetic acid and exopolysaccharide in submerged cultivation. These 5 isolates were identified as Pantoea sp. K8AcR2AY004, Chitinophaga eiseniae K4NRBAY001, Pantoea dispersa K4NRR2AY011, Bacillus marisflavi K7SpZMAO002 and Bacillus wiedmannii K3AsBAP008 using biochemical and molecular characterization. These strains were studied for their abilities to promote cowpea growth in vitro and using sand-filled pots. Cowpea seeds treated with C. eiseniae K4NRBAY001, P. dispersa K4NRR2AY011 and B. marisflavi K7SpZMAO002 in sand exhibited higher germination rate, vigor index and growth parameters than uninoculated seeds. The present study demonstrates that bacterial strains from CSD have the potential to stimulate cowpea growth and could be exploited as bio-fertilizers in arid sandy soils.