- THE FLORICULTURE VEGETATIVE CUTTING INDUSTRY 145
to the typical positive correlation of carbohydrates and rooting to the
idea that carbohydrates in that experiment were not low enough to be a
limiting factor, but nitrogen may have been. They also noted that high
light levels used during the rooting period may have allowed rapid
photosynthesis to overcome initial carbohydrate levels. Regardless of
the initial carbohydrate levels, storage of cuttings reduced carbohydrate
levels.
- Cultivar Variation.Various cultivars within a species are typically
known as good or poor ‘shippers.’ For chrysanthemum, ‘Anna’ and
‘Debonair’ cuttings tolerated cold storage for 4–6 weeks, whereas
‘Emily’ and Naomi’ cuttings were negatively affected by only 1 week
of storage (Rajapakse and Kelly 1995). The difference in storability was
linked to soluble sugar levels, which were more depleted in ‘Emily’
and ‘Naomi’ after storage than in ‘Anna’ and ‘Debonair.’ Arteca et al.
(1996) were unable to relate photosynthesis, respiration, carbohydrate,
starch, or protein content to shipping ability of various geranium
cultivars. However, for good and moderate shippers, ethylene levels
increased 3 d after the end of storage, while for the poor shippers,
ethylene rate increased only 1 d after end of storage, indicating that
ethylene may play a role in the potential storage longevity of different
cultivars.
B. Harvest
Time of harvest is an important factor influencing cutting postharvest
longevity and rooting, as noted in Section II. For most herbaceous flori-
culture crop species, stem tip or terminal cuttings are used, consisting
of an apical meristem and one or more subtending leaves. Typically, the
cutting should have at least one mature leaf acting as a photosynthate
source and one to several immature leaves. Some companies prefer to
harvest and/or use small cuttings and others larger cuttings, which can
reduce the amount of time to produce a finished plant. Cuttings are usu-
ally counted and bagged in the greenhouse or field and then placed in
a cooler, from which orders are sorted and packaged.
C. Storage Methods
Vacuum cooling or forced-air cooling is often performed to remove the
field heat from the packages of cuttings (Faust et al. 2006). However,
there has been limited work on various storage methods for unrooted
cuttings. Eisenberg et al. (1978) noted that low-pressure storage (5 kPa)