Arbuscular Mycorrhiza and Plant Growth-promoting Bacteria Alleviate Drought Stress in Walnut

Abstract

Additional index word. Azotobacter chroococcum, Glomus etunicatum, nutrient acquisition, peroxidase activity, proline, symbiotic bacteria Abstract. Drought stress is one of the main constraints limiting worldwide crop production. Arbuscular mycorrhizae (AM) and plant growth-promoting bacteria (PGPB) such as Azotobacter chroococcum and Azospirillium lipofrum have been shown to alleviate drought stress effects. Therefore, the interaction effect of AM fungi [Glomus mosseae, G. etunicatum, and a mix of these (G. mix), and PGPB bacteria (Azotobacter chroococcum + Azospirillium lipofrum)] was investigated in 1-year-old walnut seedlings (cv. Chandler) under normal and drought stress conditions. Drought stress reduced growth (plant height, root length, number of leaves, and fresh weight) and leaf nutrient content (N, P, and Zn) significantly of walnut plants. In contrast, proline, total soluble sugar, starch peroxidase enzyme activity, and total phenolic content of walnut leaves increased under this stress. Application of fungi or bacteria, and especially their simultaneous use, alleviated the negative effects of drought stress on walnut seedlings. AM fungi and PGPB increased significantly the content of some metabolites, including total phenolic content, proline level, peroxidase activity, total soluble sugar, and starch content as well as peroxidase enzyme activity. This led to an increase in walnut plant growth under the drought stress condition. Among AM fungi, G. etunicatum was more effective in reducing drought stress symptoms than either G. mosseae or the G. mix of fungi. In conclusion, use of G. etunicatum, along with PGPB, can reduce negative effects of drought stress on walnut seedlings.

Effects of Arbuscular Mycorrhizal Fungi on Growth and Physiological Performance of Catalpa bungei C.A.Mey. under Drought Stress

“…Nutrient distribution and accumulation are results of the interaction between plant and environmental factors and reflect not only the adaptability of plants to environmental factors, but also the impact of the environment on plants [89]. Previous studies suggested that the promotion of nutrient uptake by AMF is an important physiological mechanism of the mycorrhiza-induced drought resistance of the host plant [2,7]. Yang et al [8] discovered that black locust seedlings inoculated with F. mosseae and R. intraradices had enhanced leaf C, N, and P concentrations under both WW and drought stress conditions.…”

“…Drought is one of the most important factors affecting plant growth in terrestrial ecosystems [1]. Climate change increases the odds of severe drought conditions around the world [2,3]. Drought stress can change plant water status, and has obvious effects on seed germination, plant morphological structure, biomass distribution, soil nutrient availability, photosynthesis, and metabolism, thereby seriously restricting the normal growth, development, survival, and productivity of plants [3][4][5][6].…”

Effects of Nitroxin and arbuscular mycorrhizal fungi on the agro-physiological traits and grain yield of sorghum (Sorghum bicolor L.) under drought stress conditions

“…Compared with a single inoculation treatment, dual inoculation with AMF and Nitroxin resulted in a higher N content. Several studies have shown that improving the uptake of nutrients using AMF and rhizobacteria is a basic mechanism for improving the adverse effects of drought stress in plant development [20,63].…”

Exploring mycorrhizal fungi in walnut with a focus on physiological roles

“…The walnut tree has a high-water demand, so its production and tree growth can be influenced by soil drought stress (Vahdati et al, 2009). Behrooz et al (2019) tried to use G. mosseae, G. etunicatum, and a mixture of both inoculated into one-year-old J. regia cv. 'Chandler' seedlings, and found that these AMF species significantly improved the contents of some metabolites under drought stress, such as total phenolic, proline, total soluble sugar, and starch, and also enhanced activities of peroxidase.…”

“…The stimulated nutrient acquisition also was found in drought-stressed walnut plants after AMF inoculation. G. mosseae, G. etunicatum, and the mix of both collectively increased leaf N, P, and Zn contents of walnut under normal water and drought stress conditions (Behrooz et al, 2019). In Juglans regia L. Liaohe 1, Huang et al (2020) used five AMF species (A. scrobiculata, D. spurca, G. etunicatum, G. mosseae, and G. versiforme) and found that the AMF inoculations could improve plant growth performance, dependent on AMF species.…”