Effects of Sucrose on Water Relations of Cut, Senescing, Carnation Flowers

Carnation flower stems were stood in water or sucrose solutionand changes in water content, water and osmotic potential, turgorpressure and solutes (sugars, nitrogen, phosphorus, potassium)of petals were measured throughout the flower life. In bothtreatments the petals had a higher specific water content atincipient wilting than when the flowers were first cut. In water,turgor pressure decreased rapidly after the seventh day becauseof a decrease in tissue solute content. In sucrose solution,loss, of solutes was delayed probably because the sugar provideda respiratory substrate to maintain cell membrane integrity.In these cells, sugars and water accumulated causing decreasesin water potential and osmotic potential. Solutes and waterwere lost at about day 15 and turgor pressure decreased. Therewas some evidence that from about day 11 cells were so gorgedwith sugars that they burst when they were placed in water duringthe adjustment of water content prior to water potential measurements. Most of the initial petal osmotic energy content could be accountedfor by sugar, potassium, and anions associated with potassium,but in water, as the petals aged and sugar content decreased,so the potassium ions contributed a larger proportion of theosmotic energy; with stems in sucrose, the endogenous sugarcontent (reducing sugars plus sucrose) contributed an increasingproportion of the total osmotic energy. Dianthus caryophyllus, carnation, flowers, water relations, senescence