Effects Of Cadmium On The Growth And Development Of Lotus (Nelumbo Nucifera Gaertn)

Lotus (Nelumbo nucifera Gaertn.) is planted widely in China. It has been the most important water vegetable. The effects of cadmium on the growth of lotus are investigated in this paper. "No.2 of Whzhi" is adopted in this experiment. Lotus were planted in cement pools with different Cd content(0, 0.2, 0.4, 0.8, 1.2, 1.6mg/kg).The background accords with National Class I standard. The main results obtained as bellow:1. Cd affects the growth of leaves significantly. Contrasted with the control, leaf amount and height are increased under low Cd concentrations (Cd<1.2mg/kg) and decreased in the treatment of 1.6mg/kg. With the rising of Cd concentration, the leaf area is decreased significantly.2. Cd affects the photosynthesis characteristic of leaves significantly. The analysis of leaves in different growth period showed that the chlorophyll content, chlorophyll a/b, and photosynthesis rate decrease while intercellular CO₂ concentration increase with the rising of Cd concentration. Transpiration rate and stomata conductance of leaves either increases (Cd<0.8mg/kg) or decrease (Cd>0.8mg/kg). Changes of the photosynthesis characteristic of leaves have correlation with leaf age.3. Cd affects the activity of antioxidant enzymes in lotus significantly. The analysis of leaves in different growth period showed that Cd either stimulates (<0.4mg/kg) or inhibits (>0.8mg/kg) activity of SOD and POD. With the rising of Cd concentration, soluble protein content decreases while Pro and MDA increase. Changes in lotus root are the same as those in leaves.4. Cd affects the yield of lotus root significantly. The results suggested that promotion of growth appear when Cd concentrations in culture are below 0.8mg/kg.5. Cd treatments affected the quality of lotus root significantly. Vc content either increased (Cd<0.8mg/kg) or decreased (Cd>0.8mg/kg). With the rising of Cd concentration, amylum and soluble protein content decrease when Cd concentrations are below 0.8mg/kg. The analysis of roots in different parts showed that all of these indexes vary in different parts of lotus root under different Cd treatments.6. The accumulation of Cd varies in different organs. Roots have higher Cd content than leaves do. Either in leaves or in roots, Cd content increased with ages adding. Cd inhibits the absorption of Ca and Mg in lotus.