CUT-ROSE PERFORMANCE: RESULT OF A TOUCHY BALANCE

Cut roses in plain water under our conditions vary widely in performance; nonetheless, their corollas always show considerable import of dry matter and reach dry weights similar to that of intact ones. This means that there is a close relationship between final percentage of corolla dry matter on the one hand, and evolution of fresh weight and visual appearance of flower and foliage on the other.

Water-treated cut roses can be made to perform better by a variety of experimental procedures: cooling the cut surface to 0°C; short exposure of the cut surface to silver; substituting lateral water uptake, via bark-stripped lengths of stem, for cut-end uptake.

Conclusions:

• Cut 'Sonia' in water in principle is capable of good performance.
• Even then, water turnover decreases considerably.
• Water-uptake capacity diminishes through processes at the stem cut-surface (microbial and/or wound reactions).
• Transpiration rate is the result of conflicting stomatal responses: opening by the light stimulus, closure by developing water stress.
• Cut-rose performance depends on a delicate balance of diminishing uptake capacity and actual transpiration.
• A slight disturbance of balance irreversibly triggers a chain reaction in the wrong direction.
• Sugar in preservative formulas plays a multiple role.

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