Without rigorous and cumbersome precautions, air will be sucked into the water conducting channels when a plant stem is cut while in a state of tension, which is the normal state during the day time.
The resulting 'air embolism' may seriously interfere with the severed part's subsequent water uptake.
For this reason 'recutting under water' is a generally recommended measure in cut-flower handling (Rogers, 1973). While for all practical purposes this measure may be quite satisfactory, in more critical work, however, there remains some uncertainty concerning its real efficacy, e.g. in relation to the length of stem that should be cut off to exclude all air-filled xylem vessels (this depending on the free vessel lengths).
In our own studies on the water balance of cut and intact roses we could circumvent complications of air embolism by using hydropondically-grown single-stem rose plants: De Stigter 1980. Nonetheless, it would still be desirable to have a workable method for cutting embolism-free parts from branched plants growing in soil.
The method to be described here meets the various requirements implied, and is carried out in two steps.
In the first step, a small water reservoir is fitted around the part of stem selected for cutting: Fig. 1. In the second step, the stem plus water reservoir are cut with a special pruning tool modified from a commercially available 'blade-and-anvil' type: Fig. 2. On the 'anvil' an aluminium platelet is welded, at right angles and flush with the cutting face.
On the cutting blade a hollowed-out block is cemented, precisely parallel to the anvil plate, so that the cutting edge protrudes ca. 2 mm.
On the anvil plate, opposite the inner faces of the cutting-blade block, are glued pads of closed-cell foam rubber, the thickness of which should be such that they can be compressed to less than the width of the protruding cutting edge.
When operated, the parts described together form a leak-proof well which will hold the water pouring out from the cut reservoir surrounding the stem.
The water actually starts pouring out during the instant when the blade has already passed through the reservoir wall and is about to cut its way through the stem's bark and wood.
So from the very beginning the cut is bathed in water which effectively eliminates the possibility of air being sucked into the xylem vessels.