Water relations and keeping-quality of cut Gerbera flowers. II. Water balance of ageing flowers

Abstract

Time course of fresh weight (F.W.), water content as percentage of dry weight of petals (W.C.), maximal water content after saturation of petals (W.C. max), relative water content of petals (R.W.C.), absorption rate (abs.), transpiration rate, water potential of petals (ψ), stem flow resistance (R stem) and flower developmental stage of cut Gerbera flowers in solutions with chemicals were determined. In a solution with silver nitrate, an increase of R stem was evident after 4 days, resulting in a decrease of abs., F.W., W.C., R.W.C. and ψ. A constant pH of the vase water of 3.5 could prevent this increase in R stem. The pH of the vase water was influenced by the flower itself. When the increase of R stem was prevented, the absorption rate was higher than the transpiration rate during the first 5 days after cutting, which resulted in an increase of F.W., W.C. and R.W.C. After day 5, absorption was lower than transpiration, the F.W., W.C., W.C. max and R.W.C. decreased, while ψ remained steady. It is suggested that the water deficit-water potential relationships of the petals change with age, resulting in a lower water-holding capacity of the petals.