Water relations and keeping-quality of cut Gerbera flowers. I. The cause of stem break

Abstract

Experiments were performed to find out the cause of stem break in some Gerbera cultivars. In cut flowers fresh weight decreased sharply 3 days before stem break occurred, and this was accompanied by a decline in absorption of water by the flowers. The petal water potential (ω) decreased in these flowers whereas it remained constant in flowers without stem break. Stem break could be prevented by pretreatment of the stems with sodium hypochlorite or silver nitrate, by adding silver nitrate or dichlorophen to the vase water, and by handling the stems in such a way that water could enter into the cavity of the stem. In 1 of the 4 cultivars used, the percentage of stem break varied strongly between summer- and winter-grown flowers. It is suggested that there are 2 different pathways for water uptake: a direct one through the xylem vessels at the cut surface and an indirect one through the cavity in stem. Only the direct water uptake is strongly inhibited by growth of bacteria in the vase water. Stem break occurs when the direct water uptake is inhibited by bacterial activity and the indirect uptake is hampered.