THE CONTRIBUTION OF CURRENT PHOTOSYNTHESIS TO GROWTH AND DEVELOPMENT IN THE TULIP DURING FLOWERING

Abstract

Leaves of tulip plants were treated with 14CO2 on three occasions during flowering, one week apart–at the bud stage, at early flowering and when flowers were fully opened. The amount of 14C fixation was examined 5 min after a pulse application of 14CO2 and the organic carbon and 14C contents of various organs were examined 24 h later. Total carbon in the mother‐bulb scales fell over 14 days to only 40% of the initial value, whilst that of all new organs increased by 71%. A negligible amount of 14C was recovered from scales or from roots. The 14C recovered from the flower and stem accounted for 83% of 14C exported from leaves at the early flowering stage. The total carbon content of the daughter bulbs increased uniformly with time but the 14C recovered from the daughter bulbs was initially smail but increased to 59% of the exported 14C when the flower was fully opened. The imported 14C in flower and stem was mainly recovered from the soluble and residual (non‐starch, insoluble) fractions, whilst that in daughter bulbs was from the soluble and starch fractions. The amount of 14C lost by respiration fell from 20% to 10% of initial 14C uptake over the 3‐week period. Copyright © 1977, Wiley Blackwell. All rights reserved