Effects Of Cadmium Levels On Growth And Development And Physiological Metabolism In Balsam Pear

Six levels of cadmium(0, 20, 40, 80, 160, 320 mg/L),using sand culture experiment,were given to study the effects of cadmium on the growth ,development and physiological metabolism in balsam pear (Momordica charantia Taiwanbiyu).The main results were submitted as fellows:1) Under the stress of cadmium,the normal growth,development of balsam pear were affected.ln the concentration of Cd²⁺<80 mg/L,the effect to balsam pear growth was not significant;but in the concentration of Cd²⁺>80 mg/L,the normal growth,development of balsam pear were affected significantly,and the effects were intense along with further cadmium stress.Cadmium stress did not affect balsam pear seedling notably;but after seedling ,high concentration of cadmium stress badly affected the growth ,development of balsam pear,and with Cd further stress,the effect of Cd was increasing.2) Under the stress of cadmium,the growth of balsam pear shoots and roots were dramatically inhibitet. Cd inhibited the shoot growth of balsam pear ,such as plant height,stem diameter,the length of stem section,the number of leaves on main vine ,the size of leaf ,the cumulation of shoot dry weight ;it also inhibited the normal growth and dry weight of balsam pear root.3) Under the stress of ca dmium,the normal period of balsam pear bearing time was significantly affected .In the concentration of Cd²⁺ 40 mg/L,balsam pear's normal bearing time was affected,such as the number of side vine,flower,female flower,fruiting;and in the concentration of Cd²⁺>80 mg/L,balsam pear's normal bearing time was completely inhibited.4) Under the stress of cadmium,the content of balsam pear leaf pigments was affected.and then affected the biological outputs.5) Under the stress of cadmium,the activity of balsam pear leaf nitrate reductase(NR) fell.The content of protein fell too.Except that under the stress of Cd²⁺20 mg/L,the content of balsam pear leaf' protein was higher than the CK.6) Under the concentration of Cd²⁺20 mg/L,balsam pear leaf's superoxide dismutase (SOD),catalase (CAT)activities were stimulated.But with Cd futher stress ,the activites of SOD,CAT were inhibited.7) Under the stress of cadmium,balsam pear clear up superfluous active oxygen by dint of GSH-AsA cycle.Under the stress of cadmium ,balsam pear leaf's ascorbate peroxidase(APX) activity was active ,and it protected the balsam pear .In some concentration of cadmium,the activities of balsam pear leaf's dehydroascorbate reductase(DR),Glutathione Reductase(GR) enhanced,but the activites were inhibited beyond the some concentration of cadmium.8) Under the stress of cadmium ,balsam pear leaf's cell membrane and the content of MDA enhanced,it wasindicated that balsam pear was damaged by the stress of cadmium.9) Under the stress of cadmium, the content of free proline in balsam pear leaves was cumulated,and it protectedbalsam pear.But the increase was lower in the high concentration and further stress of Cd.10) The generation of O₂^-and H₂O₂ content increased under Cd stress. And the generation of O₂^-increased athigh level in Cd²⁺160 mg/L, then declined.lt showed that the leaf of balsam pear was damaged in thehigh-concentration Cd.