Rihab Djebaili
Abstract
The excessive use of chemicals in agriculture has deleterious effects on soils, with negative consequences on crop productivity. New biological approaches are required to improve agricultural productivity without altering the environment and living organisms. Plant-growth- promoting rhizobacteria (PGPR) can be a valid tool to achieve these goals. The aim of the present study was to evaluate the capability of some actinomycete isolates to colonize roots and stimulate plant growth and development of tomato (Solanum lycopersicum L.). Sixty actinomycete strains were isolated from two saline soils of northeast region of Algeria - Ezzemoul sebkha and Djendli sebkha. Strains were first characterized in vitro for their capability to solubilize phosphate, produce indole acetic acid, hydrocyanic acid, and ammonia, and for the presence of different enzymatic activities. Then, strains that obtained best in vitro results were investigated for their root colonization ability by scanning electron microscopy and utilized in a greenhouse experiment to assess inoculation biostimulant effects on tomato plants. Among sixty isolates, fourteen PGPR were selected based on their plant-growth promoting traits. These strains, belonging to Streptomyces sp. and Nocardiopsis sp. genera, showed good association capability with tomato plants in vitro. Greenhouse experiment results showed that tomato plants were positively influenced by actinomycete inoculation. Inoculated plants showed better growth and morpho-physiological characteristics with respect to the control. Results obtained suggest that these actinomycetal strains could be used as biofertilizers. The investigation and the development of these products should be encouraged to reduce the use of chemical fertilizers to improve environment quality and preserve living organism’s health.