Effects Of Cu,Zn,Pb On The Growth Of Soybean Seedling And Photosynthetic Characteristics Of Cotyledon

Soybean(Glycogen max (L.) Merr) tender seedlings are cultured in solution culture to research the contents of chlorophyll a, b and carotenoid, photosynthetic rate and carbonic anhydrase activity in the physiology procedure of soybean cotyledon, and the effects of copper, zinc, lead on the growth of soybean seedlings and cotyledon photosynthetical system. All of these provide evidence for regarding the carbonic anhydrase activity as a biological index in the environmental inspection.According to the results of these experiments in the paper, the following conclusions can be drawn:(1) The photosynthetic pigment contents, carbonic anhydrase activity and photosynthetic rate change according to the physiological functions of cotyledon. At the beginning, they increase with the development of the cotyledon, and achieve the maximum on the seventh day, and descend gradually with the withering of the cotyledon.(2) when copper, zinc and lead directly interact with the carbonic anhydrase extracted from the soybean cotyledon, copper or zinc less than 0．0001mmol/L can improve the activity of carbonic anhydrase ex vivo, but that higher than 0．001mmol/L inhibits the carbonic anhydrase ex vivo. But lead inhibits the carbonic anhydrase ex vivo even when the concentration is very low. The inhibiting constants of copper, zinc and lead to CA from Nannong493-1 and Tongsul cotyledon are approximately: 0．75mol/Land0．65mol/L, 1．50mol/Land 1．40mol/L, 1．05mol/Land 1．10mol/L.(3) Copper or zinc less than 0．5mmol/L facilitates the growth of the soybean seedlings, increases the contents of photosynthetic pigment, and strengthens the photosynthetic rate of the soybean cotyledon and the cotyledon carbonic anhydrase activity. But copper or zinc of 5．0mmol/L inhibits the growth of tender seedlings and degrades the parameter value of photosynthetic characteristics of the soybean cotyledon. There are not obvious changes in the contents of photosynthetic pigment, photosynthetic rate and carbonic anhydrase activity when seedlings are treated with lead less than 0．005mmol/L,but lead higher than 0．05mmol/L inhibits the growth of tender seedlings, reduces the contents of photosynthetic pigment and photosynthetic rate and carbonic anhydrase activity. In the process of the complex experiments of copper, zinc, lead, there is antagonism between the metals.(4) Associativity between the carbonic anhydrase activity, photosynthetic pigment contents in the soybean cotyledon and net photosynthesis rate shows that whether the soybean tender seedlings grow in the normal circumstances or are affected by copper, zinc and lead respectively or together, the correlation is notably positive.