Contribution of Pink Pigmented Facultative Methylotrophic Bacteria in Promoting Antioxidant Enzymes, Growth and Yield of Snap Bean

摘要

Two field experiments were carried out during the seasons of 2013 and 2014 to investigate the effectof pink pigmented facultative methylotrophic (PPFM) bacteria on the antioxidant enzymes, growth and yieldof snap bean plants. The PPFM were isolated from different plants: cotton, datura, snap bean, castor oil andpeanut plants. Isolates were compared based on their productivity of indol-acetic acid and cytokinins.Isolate No. 27 was selected due to its high production of both growth hormones and used for plant treatment.The treatments included control (distilled water), foliar application of PPFM, methanol (MeOH) at 5% and thecombination of PPFM + MeOH at 5%. Results indicated that spraying the plants with PPFM individually orcombined with methanol changed the level of antioxidant enzymes including polyphenol oxidase (PPO),peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD). Also, the lipidperoxidation as indicated by malondialdehyde (MDA) and morphological studies by scanning electronmicroscope (SEM) were examined. The PPFM individually achieved the highest significant increases in thenumber of leaves per plant, average leaf area, haulm fresh weight, leaf chlorophyll, pod number and yield perplant and Feddan in the two seasons compared to the other studied treatments. Moreover, PPFM individuallyimproved the pods quality by increasing their concentrations from amino acids, protein, total sugars andascorbic acid. Correlation analysis indicated that APX followed by POD as affected by the treatment of PPFMindividually related positively to snap bean yield plant 1 while, catalase followed PPO affected inversely thistrait in both seasons. The SOD was unstable and may not be related to the quantity of yield.