イネの生育に伴なう葉のRuDPカルボキシラーゼ活性・葉緑素含量等の消長とそれらの相互関係について

抄録

Ribulose-1, 5-diphosphate (RuDP) carboxylase, catalase and acid phosphatase activitics, and chlorophyll and soluble protein contents expressed in term of unit leaf area were investigated at various stages of leaf growth in pots. The following results were obtained : (1) When the leaf blade was divided into three equal parts, RuDP carboxylase activity of each part of young leaf blade immediately after it had fully expanded showed the ranking order: middle≥top<base. The activity of the aged old leaf showed the ranking order: base<middle<top. But the mean activity in the whole leaf blade was considerably lower in older leaf than in expanded younger one. Changes in RuDP carboxylase activity also had a similar pattern to soluble protein content, but not to chlorophyll content in all leaf parts. (2) When RuDP carboxylase activity in different position of leaf blades was measured at various stages of leaf growth, the results were obtained that the mature top leaf which completely expanded had the highest activity and as the leaf positions dropped down, RuDP carboxylase activity of each leaf decreased drastically. RuDP carboxylase activity of developing immature leaf was as low as that of lower leaf position. Chlorophyll content of leaf blade attained its maximum at the lower leaf than the mature top leaf and their differences among various leaf positions were observed after young panicle formation stages, but not at early growing stages. (3) After heading date, RuDP carboxylase activity of flag leaf was maintained at relatively higher levels untill toward the yellowing stages. During these stages, soluble protein content, chlorophyll content, and catalase activity of each leaf changed parallel with RuDP carboxylase activity, respectively, but acid phosphatase activity increased with the ageing of expanded leaf blades. (4) The correlation evident between RuDP carboxylase activity and soluble protein content observed through the growing stages (table 3 and 4.) indicated that there was a parallel correlation between RuDP carboxylase activity and photosynthetic rate when we referd to the past some observations that protein-nitrogen content of rice leaf was closely correlated with the photosynthetic rate. Chlorophyll content also changed parallel with the RuDP carboxylase activity through growing stages except for the early stages. But the degree of the parallelism between the two was lower than that between RuDP carboxylase and soluble protein content.