Effects of Plant Growth-promoting Rhizobacteria on Growth and Physiological Characteristics of Zizyphus jujuba Seedlings Under Drought-stress

The effects of inoculated with plant growth-promoting rhizobacteria (PGPR) of T₁ (Pseudomonas koreensis), T₂ (Bacillus filamentosus) and mixtures (T₁∶T₂, 1∶1) on growth and physiological characteristics of Zizyphus jujuba seedlings under different water deficit conditions were evaluated by pot experiment. The results showed that inoculation with the 3 bacterial inoculants significantly increased the plant height, dry weight, net photosynthetic rate, and chlorophyll content (P<0.05) under any water conditions. The contents of malondialdehyde (MDA) and abscisic acid (ABA) in the leaves reduced in different levels. Antioxidant enzyme activities showed the opposite trends. The inoculation effects were better with the aggravation of drought stress. Under serious drought stress conditions, the MDA and ABA contents in inoculated plants decreased by 25.2%, 20.9%, 43.1% and 14.5%, 12.2%, 27.1%, respectively. The activities of peroxidase (POD), superoxide dismutase (SOD), proline (Pro), and heteroauxing (IAA) contents increased by 22.0%-39.4%, 19.5%-30.5%, 14.0%-17.7%, and 59.7%-104.8% (P<0.05). In conclusion, inoculation with the 3 bacterial inoculants could enhance drought tolerance of jujube seedlings by regulating photosynthesis, antioxidant enzyme activities, and decreasing the accumulation of lipid peroxidation products. The best inoculation effects were observed in mixed inoculations. P. koreensis and B. filamentosus have promotion patent and broad applied foreground in arid regions.