Evaluation of bean and maize on interaction with lichen isolate bacteria under saline stress
Abstract
Soil salinization results from both natural and anthropogenic processes, including inadequate irrigation practices and the improper application of fertilizers. Different studies have demonstrated the beneficial role of phosphate-solubilizing bacteria (PSB), such as Bacillus sp. and Stutzerimonas sp., in improving the growth of plants under stress conditions. This study aimed to evaluate the development of maize (Zea mays) and bean (Phaseolus vulgaris) plants subjected to salt stress in a capillarity system, both in the absence and presence of seven different Bacillus sp. and Stutzerimonas sp. strains isolated from lichens collected in Guanajuato. Seeds were disinfected using chlorine gas and placed on bond paper inside cellophane bags (n = 6 per treatment). Inoculation was carried out with 0.02 mL aliquots of bacterial cultures. Salt stress was imposed by the addition of sodium chloride solutions (0.075 M and 0.1 M). Plants were maintained under a 16 h light/8 h dark photoperiod, and growth was monitored for two weeks. Evaluated parameters included the germination percentage and total plant and root length. Data were statistically analyzed using ANOVA and Tukey’s test. The results indicated that under salt stress, Stutzerimonas sp. strains 21_3 and 20_9 significantly promoted maize development across all evaluated NaCl concentrations. At 0.075 M NaCl, both strains maintained 100% germination; however, at 0.1 M NaCl, germination with strain 21_3 decreased to 83.33%, whereas strain 20_9 maintained 100%. Furthermore, root length analysis revealed that strain 20_9 stimulated root elongation beyond its water controls, while strain 21_3 maintained growth comparable to unstressed controls. In conclusion, Stutzerimonas sp. 20_9 functions as a highly effective halotolerant plant growthpromoting bacterium capable of mitigating salinity stress and stimulating root architecture development in maize. This study highlights the biotechnological significance of lichen-associated microbiota for agriculture, offering a strategy to enhance crop resilience and productivity in salinized agricultural soils.