Ontogenetic changes in the contents of ribulose-1,5-bisphosphate carboxylase/oxygenase, phosphoenolpyruvate carboxylase, and chlorophyll in individual leaves of maize

Abstract

Abstract Contents of nitrogen, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEPC) and chlorophyll in individual leaves of maize were measured during growth, and the following results were obtained. 1. According to the changes in the nitrogen content, each leaf was subdivided into 3 classes: class I, 2nd to 6th leaf emerged at the early vegetative stage, class II, 8th to 12th leaf emerged during the reproductive growth stage, and class III, 14th to 18th leaf emerged during the booting stage. During the vegetative growth stage, class I leaves played an important role in nitrogen retranslocation as well as carbon assimilation because the ratio of the amounts of Rubisco-N, PEPC-N, and chlorophyll to the amount of nitrogen decreased rapidly after reaching a maximum value, indicating that photosynthetic components were decomposed preferentially for nitrogen retranslocation. During the maturation stage, class II leaves contributed mainly to the supply of nitrogen to...