PLANT WATER STATUS AND CO2 FIXATION OF ROSES AS AFFECTED BY SEASON, IRRIGATION AND CANOPY WETTING

Z. Plaut, N. Zieslin
A diurnal pattern of shoot water potential (psi) of greenhouse roses was obtained regardless of season, irrigation regime and canopy wetting. Water potential decreased gradually from the early morning until 10.00–11.00 hours and remained at minimal values throughout midday, followed by an increase in the afternoon. The minimal (psi) values of roses grown under a very frequent irrigation regime were in the summer only 1–2 bars, lower than in the winter. Less frequent irrigation reduced midday (psi) values by 2–6 bars. Canopy wetting increased water potential only slightly, mainly in the spring.

A decrease in CO2 fixation rate was obtained during midday hours when radiation flux density was maximal, and this was mainly attributed to the increased plant water stress. This decrease was not prevented by canopy wetting in spite of its effect on the reduction of plant surface temperature.

It is suggested that the reduction of CO2 fixation rate under impaired plant water status was due to both increased stomatal resistance under stress conditions.

Plaut, Z. and Zieslin, N. (1979). PLANT WATER STATUS AND CO2 FIXATION OF ROSES AS AFFECTED BY SEASON, IRRIGATION AND CANOPY WETTING. Acta Hortic. 89, 123-124
DOI: 10.17660/ActaHortic.1979.89.20
https://doi.org/10.17660/ActaHortic.1979.89.20

Acta Horticulturae