Physiological studies of in vivo and in vitro water requirements and water relations of Chrysanthemum morifolium Ramat

Greenhouse grown Chrysanthemum morifolium Ramat. showed a significant reduction in plant water status under both sunny and cloudy conditions in response to depriving them of water. Water potential, osmotic potential, and pressure potential proved appropriate parameters for indicating plant water status. Diurnal changes in water status indicated more variable levels during the day than at night. The most stable and representative water status occurred just before sunrise. The pressure chamber and vapor pressure osmometer appeared to provide valid characterization of tissue water status. Measurements made on midage leaves appeared more representative and more consistent than those on young or older leaves.Net photosynthesis and stomatal conductance responded positively the first 2 days of water deprivation but were severely reduced with prolonged deprivation. Intercellular CO$\sb2$ concentration apparently did not change in response to water deprivation whereas expansion growth showed a rapid and significant decline with advancement of water deprivation and decrease in water potential. Microcomputerized video image analysis proved an effective method of measuring leaf expansion growth.Chrysanthemum did not survive more than 7 days of water deprivation under the experimental conditions, indicating their relatively high sensitivitity to water stress.In vitro grown Chrysanthemum proved an accurate indicator of plant response to water deficit. Stress was induced by incorporating sucrose (0.078 to 0.216 M), sorbitol (0.0 to 0.4 M) and mannitol (0.0 to 0.4 M) into the media. This osmotic stress tremendously regulated cell osmotic adjustment. Shoot length, weighted density, and shoot area all declined with the water stress induced by sorbitol and mannitol, while an inconsistent response was observed with sucrose. The change in tissue osmolarity was not retained when the cultures were transferred back to a normal media (non-stress media). Rooting proved to be metabolically rather than osmotically affected.U of I OnlyETDs are only available to UIUC Users without author permissio