Identification of two Herbaspirillum strains and its growth-promoting effect on Vetiveria zizanioides L. under coal gangue stress

Abstract:

[Background] Combined plant-microbial remediation technology plays an important role in reducing environmental stress, enhancing plant resistance and improving mining landscape. Rhizosphere microorganisms can interact with plants which can promote plant growth and enhance the tolerance of plant on abiotic stress. [Objective] To identify two strains of rhizosphere bacteria isolated from copper tailings, in order to study the growth-promoting properties of the two strains and determine the influence of the two strains on V. zizanioides grown on coal gangue. [Methods] 16S rRNA gene sequence identification and scanning electron microscope observation were performed on P5-11 and P5-19, the growth-promoting properties of the strains were measured. The strains were inoculated into V. zizanioides grown in coal gangue covered with 5 cm soil and coal gangue mixed with 10% soil. After two months, the physical and chemical indexes and physiological indexes of V. zizanioides were measured. [Results] P5-11 and P5-19 were Herbaspirillum, which had the functions of nitrogen fixation, phosphate-dissolving, produced indole-3-acetic acid (IAA) and siderophore. Among them, the IAA production capacity of P5-19 was about twice that of P5-11, and it had better growth-promoting properties. Herbaspirillum inoculation could improve plant height, biomass, total nitrogen accumulation and the antioxidant enzyme activity, and reduce the malondialdehyde accumulation. [Conclusion] The two strains of Herbaspirillum had good growth-promoting properties, which could promote the growth of V. zizanioides under coal gangue stress, which not only provided excellent strains for the preparation of microbial fertilizer, but also provided reference value for the application of V. zizanioides in the ecological restoration of mining areas.