The Effect of Root Pruning and 6-Benzylaminopurine on the Chlorophyll Content,14CO2Fixation and the Shoot/Root Ratio in Seedlings of Pisum sativum L

Pruning the roots of light-grown pea seedlings every 4 days accelerated senescence of older leaves and reduced their rate of fixation of14CO2. Application of 6-benzylaminopurine to the shoot largely compensated for root removal and increased the shoot/root ratio of both pruned and intact plants. It is suggested that the supply of cytokinins from root to shoot may affect leaves by delaying senescence and maintaining their capacity for photosynthesis; it may also alter the distribution of dry matter within the plant by influencing the proportion of assimilates and other metabolites retained by the shoot.