PROCESSES AND XYLEM ANATOMICAL PROPERTIES INVOLVED IN REHYDRATION DYNAMICS OF CUT FLOWERS

Abstract

In cut flowers, which are harvested in air and transported dry, all cut xylem vessels in the basal part of the stem contain air instead of water. These air-emboli initially block water transport at the start of vase life, but usually (partly) disappear during the first hours of vase life, resulting in rehydration of the flower. However, in some cases flowers are not able to sufficiently remove these air blockages, resulting in a poor water status expressed by wilting. Differences in rehydration ability are present between cultivars, but also between different lots of flowers within one cultivar as result of growing conditions. Using chrysanthemum cut flowers, investigations are focussed on the dynamics of the flower water status during the first hours of vase life after air entrance in the xylem vessels via the cut surface. Role of xylem anatomy in the process related to the establishment of a good or bad rehydration are studied by means of cryo-SEM and other microscopic techniques, dynamic measurements of stem hydraulic resistance and 1H NMR imaging. Modeling techniques are use to explore theoretical concepts and to integrate experimental results obtained by the different experimental techniques.