Carbohydrate movement in pea plants in relation to axillary bud growth and vascular development

Abstract

The dormant bud in the axil of leaf 4 of pea plants (Pisum sativum cv. Alaska) began to elongate within 4 h of removal of the shoot apex. Within 24 h after decapitation there was an increase in the uptake of 14C-labeled assimilates by the bud, following the assimilation of 14CO2 by the lamina of leaf 4, and an increase in total sugar per bud. Starch was present in the inhibited bud and also increased within 24 h of decapitation. Complete vascular differentiation and the formation of additional xylem elements was not evident until 48 h after decapitation. The localization of soluble sugars in the bud trace, determined by microautoradiographic techniques, suggested that differentiation of the phloem did not greatly precede that of the xylem. This sequence suggests that apical dominance was not acting through inadequate development of the bud vascular system.