Effects of Rhizobacteria Inoculation on Germination and Physiology Status of Tomato under Salt Stress

Abstract

The aim of this work is to explore the effect of inoculation with native
rhizobacteria strains isolated from steppe ecosystems on enhancing salt tolerance of
tomato (Solanum lycopersicum L.). For this purpose, various rhizobacteria strains have
been purified, identified, and then applied on tomato seeds, in vitro then in pots
to study their effects on the germination parameters and growth under salt stress.
Eight genera of rhizobacteria strains were identified; they displayed pertinent plant
growth promotion features such as phytohormones biosynthesis, fixation of atmospheric
nitrogen, and phosphate solubilization. The obtained results demonstrated that salinity
negatively affected seed germination and impaired plant growth. In response to salt
stress, uninoculated plants accumulated a significant amount of osmoregulators (proline
and glycine betaine), and recorded a decrease in their chlorophyll content, compared to
inoculated plants, where the salinity tolerance has been much better with a high seedling
growth as well as high chlorophyll and low osmolyte contents. Among the eight strains
used in this study, three (Agrobacterium, Citrobacter and Enterobacter) demonstrated their
effectiveness in enhancing salt tolerance of tomato plants. The use of native rhizobacteria
strains as biofertilizer could be a sustainable approach to improve plant growth in
salinity-impacted regions.