Abstract:

Soil salinization is a global ecological problem restricting agricultural production, and its bioremediation technology has attracted much attention. In this study, salt-tolerant strains were isolated from saline-alkaline soil in Tianjin, and the salt-promoting ability of the strains on maize seedlings was assessed by NaCl medium screening, 16S rRNA gene identification, and sand culture test. Three salt-promoting strains (WQ-08, WQ-26, and BH-39) were isolated and identified as Bacillus subtilis, Priestia megaterium, and B. pumilus, respectively. Under 100 mmol/L NaCl salt stress, when strains WQ-08, WQ-26 and BH-39 were respectively added for co-cultivation with maize seedlings, the growth inhibition of maize seedling MC812 was significantly alleviated: the plant height, stem-leaf dry weight and root dry weight in the WQ-08 treatment group increased significantly by 33.32%, 37.04% and 36.84% respectively compared with other treatments, while the root length, stem-leaf fresh weight and root fresh weight in the BH-39 treatment group increased significantly by 27.33%, 29.35% and 30.55% respectively compared with other treatments. Physiological indexes showed that the antioxidant enzyme activity of maize seedlings in each treatment group decreased significantly. In the strains WQ-08, WQ-26, and BH-39 treatment groups, the SOD activity of maize seedlings decreased by 9.77%, 5.60% and 7.71%, the POD activity by 20.44%, 22.24% and 25.27%, and the CAT activity by 34.46%, 31.27% and 23.28% (P<0.05). The study demonstrated that the three strains possessed both salt tolerance and growth-promoting abilities, which effectively alleviated the salt stress damage to maize seedlings and provided potential microbial resources for crop improvement in saline and alkaline areas.

Key words: salinization, microbial remediation, improvement of saline-alkali land, corn, salt stress, salt tolerance and growth promotion, Tianjin