Effects of Seed Priming with Plant Growth Promoting Bacteria on Some Physiological and Biochemical Characteristics of Okra (Abelmoschus esculentus L.) Seedlings under Low Temperature Stress

In this study an experiment was conducted based on completely randomized design in research greenhouse of Mohaghegh Ardabili University in 2014. Treatments consisted of inoculated seeds by Pseudomonas putida strains 1, 10, 19 and 150, Pseudomonas fluorescence strains 69 and 159, combination of strain 19 from Pseudomonas putida and strain 69 from Pseudomonas fluorescence and control (without inoculation). Plants were kept in greenhouse until six-leaf stage then exposed to low temperature stress (8 ºC temperature for 270 minutes during five consecutive days). After exposing plants to low temperature stress, traits such as seedling height and dry weight, photosynthetetic pigments, total carbohydrates, proline, membrane integrity, protein amount, catalase, peroxidase and poly phenol oxidase enzymes were measured. Results indicated that primingof okra seeds with plant growth promoting bacteria increased seedling height and dry weight, physiological and biochemical characteristics. Pseudomonas putida and Pseudomonas fluorescence increased cell membrane integrity via increase in leaf proline content, total soluble carbohydrates and antioxidant enzymes. The greatest promotion of seedling growth under low temperature was obtained by priming of seeds with Pseudomonas putida strain 150 and of Pseudomonas fluorescence strain 69.