142 J.E. FAUST, J.M. DOLE, AND R.G. LOPEZ
products depends on the air coming into contact with the absorbent, and
if the air is not passing over the absorbent at a sufficient rate, ethylene
typically will not be reduced enough to prevent damage. Absorbents
come in small packages, which can be included in a packed box or can
be used as air filters in cold storage or other facilities. While these prod-
ucts can reduce ethylene concentrations, it is not always enough of a
reduction to prevent damage (J.M. Dole, unpublished).
The negative effects of ethylene can be alleviated with the use of
anti-ethylene agents. The inclusion of 1-methylcyclopropene (MCP)
during cutting storage at 18–26◦C for 72 h reduced poinsettia leaf
abscission to one-fourth that of the control (Faust and Lewis 2005b);
however, during a warm postharvest treatment (26◦C) the presence of
MCP resulted in much higher ethylene levels (2.1 ppm) than in the con-
trol (0.5 ppm), an observation that was also confirmed by Leatherwood
et al. (2016). A similar pattern of high ethylene production after MCP
treatment occurred with lantana, New Guinea impatiens, ivy geranium
(Pelargonium peltatum), petunia, and zonal geranium cuttings (Kadner
and Druege 2004; Rapaka et al. 2007b, 2008; Leatherwood et al. 2016).
Increased ethylene production of MCP-treated cuttings is thought to
occur because MCP binds to ethylene receptor binding sites, disrupting
the autocatalytic feedback mechanism resulting in increased ethylene
biosynthesis (Blankenship and Dole 2003). It should be noted that
cold storage at 10◦C also prevented ethylene production (0 ppm) by
poinsettia cuttings in both the control and MCP-treated cuttings. The
preharvest application of silver thiosulfate (STS) and silver nitrate also
increased ethylene production by cuttings, but not as much as with
MCP, and prevented symptoms of ethylene damage (Paton and Schwabe
1987; Kadner and Druege 2004). However, STS and silver nitrate can
cause phytotoxicity, which can negate the positive effects of the anti-
ethylene agents (Muller et al. 1997; Kadner and Druege 2004). TDZ,
which is known to prevent leaf yellowing in geranium, also increased
ethylene levels (Mutui 2005).
Both MCP and STS prevented the loss in quality when croton,
Epipremnum, hibiscus, and geranium cuttings were stored (Purer and
Mayak 1988; 1989; Muller et al. 1997, 1998; Serek et al. 1998; Rapaka
et al. 2008). MCP also reduced leaf abscission, cutting decay, and api-
cal blackening of lantana and portulaca due to low carbohydrate levels
after storage (Rapaka et al. 2007a, 2007b). However, both MCP and STS
reduced subsequent rooting of croton, chrysanthemum, and hibiscus
(Muller et al. 1998; Serek et al. 1998). For sweet potato, MCP reduced
rooting of unstored ‘Beauregard’ cuttings, but had no effect on ‘Evan-
geline’ cuttings, and the difference was attributed to higher ethylene