Oxygen limiting conditions are a common occurrence in root zones of most crop plants and can adversely affect nearly all aspects of plant growth and development including its survival. The objective of this study was to determine the effectiveness of a novel redox cycling agent, vitamin K 3 , and various peroxides including hydrogen peroxide, calcium peroxide and magnesium peroxide in alleviating the effects of hypoxia in bean seedlings grown in nutrient culture. All the anti-hypoxic agents including vitamin K 3 had a positive impact on the overall growth of bean seedlings under hypoxic conditions, but their responses were variable depending on the concentration. With regard to shoot growth, vitamin K 3 (5 μM) increased the leaf area significantly, by more than 58% over the hypoxic control plants and produced the highest stem fresh weight similar to calcium peroxide (20 μM) and magnesium peroxide (10 μM). In addition, the use of vitamin K 3 resulted in the highest accumulation of chlorophyll (chla + chlb) in the leaves, an increase of nearly two-fold over the hypoxic control plants. Furthermore under hypoxia, calcium peroxide (20 μM) and magnesium peroxide (10 μM) produced the highest leaf biomass (FW) followed by vitamin K 3 . Vitamin K 3 (1 μM) also favored root growth in bean seedlings under hypoxia; it produced the largest increase in root length and root biomass (DW) similar to calcium peroxide and magnesium peroxide. Based on the overall shoot and root growth response of bean seedlings to various anti-hypoxic substances under hypoxic conditions, calcium peroxide, magnesium peroxide and vitamin K 3 performed better than hydrogen peroxide. These findings show that vitamin K 3 and peroxide salts are * Corresponding author. C. B. Rajashekar et al. 3397 effective in alleviating hypoxic stress in bean seedlings and also, further highlight their potential for dealing with hypoxia in wide ranging situations.
