Abstract:
Coastal sand dunes are nutrient deficient and experience severe stresses. Yet, sand dune plants or psammophytes adapt to the prevailing stress conditions and are able to proliferate in these dunes. Plant communities in sand dunes are controlled by the interaction between biotic and physicochemical components of the sand matrix. Interactions with microbes appear crucial in obtaining inorganic nutrients or growth-influencing substances. A large number of bacteria are associated with rhizosphere and with vegetation as endophytes growing on coastal sand dunes. The distribution of activities among the different genera in this study reflected that most of the predominant isolates belong to Bacillus, Brevibacterium, Brochothrix, Cellulomonas, Kocuria, and Microbacterium genera. Among the sand dune isolates, four, highly promising eubacteria, were selected to reveal their plant-growth-promoting traits. Interestingly, Bacillus subtilis, Kocuria rosea, and Microbacterium arborescens were found to have a significant effect on plant growth promotion of Solanum melongena (eggplant), an important agricultural crop. This study has also shown the production of two exopolymers from M. arborescens that aggregate sand particles directly supporting plant growth. Plant-growth-promoting rhizobacteria (PGPR) from sand dunes, therefore, present an alternative to the use of chemicals for enhancement of growth. This work has demonstrated that sand dune rhizobacteria could have an important role in agriculture and horticulture in improving crop productivity.
