Effects of Exogenous Nitric Oxide on Physiological Metabolism Indexes of Zizyphus jujube Seedlings Under Cadmium Stress

In order to understand the effects of exogenous nitric oxide on the main appearance and physiological metabolic indexes of Zizyphus jujube seedlings under cadmium stress, hydroponic method was used to study the effects of different concentrations of sodium nitroprusside, nitric oxide scavenger, NaNO_x and sodium ferrous cyanide on the growth, photosynthetic characteristics, active oxygen metabolism and mineral nutrient contents of Z.jujube were studied under cadmium stress. The results show that cadmium stress inhibits the growth potential of Z.jujube seedlings. Different concentrations of nitric oxide could promote the increase of leaf length, leaf width, plant height, basal diameter and biomass of Z.jujube seedlings under cadmium stress, and increase the net photosynthetic rate and stomata of leaves, tomatal conductance, transpiration rate, superoxide dismutase, catalase, ascorbic acid oxidase, peroxidase activity and proline content in leaves and roots, and decrease concentration of intercellular carbon dioxide, the activity of peroxidase in roots, MDA in leaves and roots, the level of reactive oxygen species and the accumulation of cadmium. At the same time, exogenous application of nitric oxide could restore the activity of proton pump and calcium pump of plasma membrane to normal level, and increase the content of mineral elements in plant. 100 μmol/L sodium nitroprusside has the best effect on relieving stress. NaNO_x and sodium ferrocyanide do not play the same role, so the remission reaction is nitric oxide specific.