The effects of sucrose uptake from a vase medium on the starch metabolism of senescing Gladiolus inflorescences

Abstract

Commercially mature Gladiolus inflorescences (var. Commando) were treated with sucrose solutions of different concentrations after picking. The vase life, general appearance, fresh mass and volume of medium uptake of the inflorescences improved with sucrose treatment. A concentration of 30 g sucrose/dm3 appeared to be the most effective treatment. Sucrose uptake from the vase solution replenishes intracellular respirable carbohydrates, allowing a sustained high respiration rate and a prolonged vase life. When 30 g sucrose/dm3 was added to the vase solution, the activities of α- and β-amylase, responsible for the noticeable decline in the starch concentration immediately after harvest, were lower during the final stages of senescence. Application of [U-14C] sucrose showed a higher accumulation of radio-activity in the less developed terminal florets compared with the more developed basal ones, thus promoting development of the terminal florets. This investigation emphasized the importance of sufficient intracellular carbohydrate reserves to ensure an optimum vase life of Gladiolus inflorescences. Kommersieel volwasse Gladiolus-bloeiwyses (var. Commando) is met verskillende konsentrasies sukrose in die vaasmedium behandel. Behandeling met sukrose het die vaasleeftyd, algemene voorkoms, vars massa en volume mediumopname verbeter. ’n Oplossing met 30 g sukrose/dm3 word as die optimum konsentrasie aanbeveel. Intrasellulêre respireerbare koolhidrate word deur sukrose via die vaasmedium aangevul en dit veroorsaak ’n hoër respirasietempo en ’n verlengde vaasleeftyd. Die aktiwiteit van α- en β-amilase wat vir die merkbare afname in die styselkonsentrasie onmiddellik na pluk verantwoordelik is, was laer tydens die finale stadia van veroudering met die behandeling van 30 g sukrose/dm3. Daar was ’n groter akkumulasie van radio-aktiwiteit in die minder ontwikkelde terminale as in die meer ontwikkelde basale blomme met toediening van [U-14C] sukrose in die vaasmedium. Sukrose in die vaasmedium bevorder die ontwikkeling van die terminale blomme en beklemtoon dus die noodsaaklikheid van genoegsame intrasellulêre koolhidraatreserwes vir blomontwikkeling en ’n optimum vaasleeftyd.