Biological Inoculant of Salt-tolerant Bacterial for Plant Growth Stimulation under Different Saline Soil Conditions.

Using salt-tolerant bacteria to protect plants from salt stress is a promising microbiological treatment strategy for saline-alkali soil improvement. This study conducted research on growth-promoting effect of Brevibacterium frigoritolerans on wheat under salt stress, which has rarely been addressed before. The synergistic effect of B. frigoritolerans combined with representative salt-tolerant bacteria, Bacillus velezensis and Bacillus thuringiensis, to promote the development of wheat under salt stress was further studied. Our approach involves two steps: the plant growth-promoting traits of each strain were investigated at six salt stress levels (0, 2, 4, 6, 8, and 10%); the effects of single strains or in combination inoculated on wheat were studied in different salt stress conditions (0, 50, 100, 200, 300, and 400 mM). The experiment of plant growth-promoting traits indicated that among three strains, B. frigoritolerans was the strain that had the most potential for promoting wheat parameters. For single inoculation, the wheat inoculated with B. frigoritolerans showed the best performance of plant growth promotion. Moreover, the pot experiment was certified that the plant growth-promoting potential of three strains co-inoculation on wheat is better than single inoculation under salt stress condition. Up to now, this is the first report suggesting that B. frigoritolerans has the potential of promoting wheat growth under salt stress, especially combined with B. velezensis and B. thuringiensis.