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

Leaves of tulip plants were treated with [SUP14]CO[SUB2] on three occasions during flowering, one week apart--at the bud stage, at early flowering and when flowers were fully opened. The amount of [SUP14]C fixation was examined 5 min after a pulse application of [SUP14]CO[SUB2] and the organic carbon and [SUP14]C 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 [SUP14]C was recovered from scales or from roots. The [SUP14]C recovered from the flower and stem accounted for 83% of [SUP14]C exported from leaves at the early flowering stage. The total carbon content of the daughter bulbs increased uniformly with time but the [SUP14]C recovered from the daughter bulbs was initially small but increased to 59% of the exported [SUP14]C when the flower was fully opened. The imported [SUP14]C 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 [SUP14]C lost by respiration fell from 20% to 10% of initial [SUP14]C uptake over the 3-week period. [ABSTRACT FROM AUTHOR]