Kidneybean (Phaseolus vulgaris L.) and buckwheat (Fagopyrum esculentum M¨onch) seedlings grown with Hoagland solution to a height of 7 to 10㎝ in the earthen pot containing sand were used for experimental plants. One group of the experimental plants was irrigated with Hoagland solution composed of various Pb-concentrations of 0 to 1000 ppm containing 30 ppm, and the other group was irrigated with Hoagland solution composed of various P-concentrations of 0 to 1,000 ppm containing 30 ppm Pb for a month during June and July in 1979. By Pb-surplus over 100 ppm, the margins fo buckwheat were curled down and turned into yellow-brown chlorosis, but the leaves of kidneybean were become dark-green at an early stage, and then developed chlorosis, finally shedded earlier than the control. Pb-toxicity was similar to the symptoms of P-deficiency. The ratio, 3/1 of chlorophyⅡ a/b at an early stage, was unaffected by Pb-surplus or P-deficiency, but at the later stage it was altered.
ATP content with Pb-surplus of 100 ppm was decreased by 69% in kidneybean leaves and by 38% in buckwheat leaves, and it with P-deficiency was decreased by 75% in kidneybean leaves and by 43% in buckwheat leaves. In the assay of ATP content of the leaves at intervals of three hours for one day of July in the year, the rhythms of ATP level were unaffected by light or temperature although the amplitude fo the level was modified. The rhythms of Pb-surplus and P-deficiency plants were observed at the lower range of ATP content than that of control.
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