WATER POTENTIAL OF ROSES IN A COMMERCIAL GREENHOUSE IN COLORADO

Water potential in the flowering stems of the rose cultivar ‘Bridal Pink’ was determined at hourly intervals from before sunrise to sunset, once monthly, from Jan. to June 1985, in a commercial, fiberglass-covered greenhouse.
Nearly simultaneous measurements included leaf and air temperature, irradiance and relative humidity.

The data did not show clear relationships with the exception of irradiance (W m^-2) and water potential (bars) from sunrise to noon (R=0.87). Potential varied from about -2 bar before sunrise to a maximum of -13 bar, although the average daily potential was -7.6 bar.
Relative humidity was not remarkable, mean daily values ranging from 68 to 81%. Leaf temperature, however, was almost invariably below the air temperature with mean values of 19.4 and 23.0 C respectively.
Leaf temperature by as much as 10°C.

On the basis of these measurements, it appeared that cultural practices such as ventilating, heating, misting and irrigation may have been sufficient to limit minimum potentials at radiant intensities much above 800 W m^-2. Or, the considerable variability in water potentials found at high intensities might have been symptomatic of physiological adjustment to stess.

I International Symposium of the Research and Cultivation of Roses

Joe J. Hanan

https://doi.org/10.17660/ActaHortic.1986.189.17