EFFECTS OF SUCROSE ON WATER RELATIONS OF CUT, SENESCING, CARNATION FLOWERS

Carnation flower stems were stood in water or sucrose solution and changes in water content, water and osmotic potential, turgor pressure and solutes (sugars, nitrogen, phosphorus, potassium) of petals were measured throughout the flower life. In both treatments the petals had a higher specific water content at incipient wilting than when the flowers were first cut. In water, turgor pressure decreased rapidly after the seventh day because of a decrease in tissue solute content. In sucrose solution, loss, of solutes was delayed probably because the sugar provided a respiratory substrate to maintain cell membrane integrity. In these cells, sugars and water accumulated causing decreases in water potential and osmotic potential. Solutes and water were lost at about day 15 and turgor pressure decreased. There was some evidence that from about day 11 cells were so gorged with sugars that they burst when they were placed in water during the adjustment of water content prior to water potential measurements.Most of the initial petal osmotic energy content could be accounted for 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 the osmotic energy; with stems in sucrose, the endogenous sugar content (reducing sugars plus sucrose) contributed an increasing proportion of the total osmotic energy. © 1979, Annals of Botany Company.