EFFECT OF GROWTH REGULATORS CCC AND B9 ON PROTEIN AND TOTAL NITROGEN OF BEAN LEAVES (PHASEOLUS VULGARIS) DURING DEVELOPMENT

Total-N and protein-N were greatest in developing primary leaves of intact plants of Phaseolus vulgaris before the leaves were fully expanded. Treating plants with CCC or B9 delayed the time when total-N and protein-N diminished. Removing the growing point made nitrogen accumulate in the leaves and the total-N did not diminish until they were fully expanded. Treatment with CCC did not affect the amount of total-N or protein-N in decapitated plants. Apparently nitrogen moves more slowly from primary leaves of CCC-treated plants because the shoot grows more slowly and demands less nitrogen. Similarly, leaves of decapitated plants have more nitrogen because there is no shoot. When primary leaves were detached and rooted, protein continued to increase in them although they were fully expanded before they developed roots, again probably because the demand for nitrogen was small. Changes in protein were correlated with changes in chlorophyll during development.Maximum photosynthesis per leaf probably occurs before leaves are fully expanded, and the protein changes in the leaf may be closely related to the trend of photosynthesis during the life of a leaf. © 1968 OXFORD UNIVERSITY PRESS.