136 J.E. FAUST, J.M. DOLE, AND R.G. LOPEZ
production. Pinching technique impacts stock-plant branching
(Wilkins 1988) and the vegetative/reproductive nature of the stock
plant (Faust and Grimes 2005). With nemesia, for example, when a lat-
eral shoot emerges from an axillary bud, the position of that bud affects
how vegetative or reproductive the lateral shoot may be. Specifically, a
desirable vegetative shoot may produce eight nodes before a flower is
initiated, which makes it easier to harvest a cutting prior to that shoot
being reproductive, that is, the cutting will not possess flower buds that
will develop in the propagation environment. In contrast, if a lateral
shoot produces just two or three nodes prior to initiating a flower,
then any cutting removed from these shoots will flower prematurely in
propagation. The vegetative/reproductive nature of the stock plant can
be altered based on the position on the plant from which the lateral
shoots emerge. Shoots that emerge from lower node positions, toward
the base of the stock plant, will be more vegetative, that is, will have
a higher node number prior to flowering. Shoots that emerge from the
upper node positions, toward the top of the stock-plant canopy, will
be more reproductive, that is, will have a lower node number prior to
flowering. Thus, stock-plant growers can pinch shoots in the canopy
in such a manner as to stimulate the lower nodes in the canopy. This
is done by performing “hard” pinches that remove the majority of the
most immature nodes toward the top of the shoot. In contrast, “soft”
pinches remove just the top node or two, leaving the upper nodes on
the stock plant, which will form flowers quickly after the later shoots
develop.
Weekly removal of mature leaves within a stock-plant canopy is
essential for species that produce compact internodes, such as gera-
nium. Mature leaves intercept light that would otherwise be delivered
to the developing shoots within the stock-plant canopy. This is a labo-
rious and expensive cultural procedure but also a necessary one for
high-quality cutting production, since shoots that receive direct sun-
light form more compact stems, petioles, and leaves, which are all com-
mercially desirable traits for unrooted cuttings.
- Time of Harvest.The time of day at which the cutting is removed,
or harvested, from the stock-plant impacts the postharvest longevity
of some plant species. Historically, stock-plant growers try to harvest
cuttings as early as possible in the day in order to avoid harvesting dur-
ing the hottest portion of the day. However, at sunrise the plants are at
their lowest carbohydrate content of the entire day due to the respira-
tion that has been occurring throughout the night. Carbohydrate con-
centration starts increasing as the light intensity increases during the