Effect of Drought Stress and Inoculation of Mycorrihizal Fungi and Pseudomonas Spp. On some Morpho-physiological Characteristics of Roselle (Hibiscus sabdaeiffa L.)

Abstract Background and Objective: Drought stress is one of the most important environmental stress and a limiting factor for plants production in most parts of the world. The aim of study was to investigate to the role of mycorrhiza and growth promoting bacteria, Pseudomonas spp. symbiosis in increasing drought tolerance of Roselle (Hibiscus sabdaeiffa L.). Materials & Methods: The experiment was performed as factorial based on completely randomized design with 3 replications in the greenhouse of Agricultural Faculty of Mohaghegh Ardabili University in 2016. first factor included 4 drought stress levels (drought stress at flowering, 50% flowering, 100% flowering and no stress), the second factor included two species of mycorrhizal fungi (Glomus mosseae and Glomus intraradices) plus control without inoculation and third factor included growth promoting rhizosphere bacteria (Pseudomonas p-169) plus control without inoculation. Results: The results showed that by applying drought stress, the plant growth properties of Roselle such as height, number of bolls per plant, stomatal conductance, dry weight of sepals, dry weight of grain, root dry weight and root volume, 1000-grain weight, chlorophyll of leave were significantly reduced. Application of mycorrhizal fungi and Pseudomonas spp . In drought stress increased relative water content, the highest amount of which (64.37%) was obtained by inoculation with fungi which showed a 32% increase compared to non-inoculated conditions. In response to drought stress, osmotic adjustment process in Roselle was provided and proline content (7.84 mg.g-1) and antioxidant enzymes such as polyphenol oxidase (1.56 μg.g-1) increased significantly under complete irrigation conditions. Conclusion: Bacteria improved the effects of drought stress.The biological fertilizers increased drought stress tolerance by increasing growth parameters and moderate in the physiological traits such as antioxidant enzymes activity and photosynthetic pigments.