Agriculture Reference
In-Depth Information
12.5
10°C
10.0
1.7°C
7.2°C
7. 5
5.8°C
4.4°C
5.0
2.5
Nov
Dec
Jan eb
Mar
Apr
May
Time
Fig. 15.2.
A typical seasonal pattern for the respiration rate of Russet Burbank tubers stored from
November to May at five temperatures from 1.7°C to 10°C. (From Dwelle and Stalknecht, 1978;
reprinted with permission from Springer Science and Business Media.)
Factors influencing respiration rates
also indicates how the respiration rate is influ-
enced by storage temperature. Immature tubers
have very high respiration rates, and these de-
crease as tubers mature (Burton, 1964; Bethke
and Busse, 2010).
Respiration rates decline most rapidly dur-
ing the first 2 months after harvest, and reach a
minimum approximately 4 months after har-
vest. Tubers of Russet Burbank harvested in
early October have been shown to reach their
minimum respiration rate around
1
February
(Fig. 15.2
). Later in storage, respiration rates
gradually increase. This increase is observed re-
gardless of whether or not sprouting occurs, but
the magnitude of the increase is less in cases
where sprouting is prevented (Isherwood and
Burton, 1975).
The temperature for minimum tuber res-
piration is approximately
5-
7°C (Schippers,
1977a; Burton, 1978). Respiration rates in-
crease as temperature increases, and the dif-
ferences between tubers stored at 4.4, 5.8, 7.2,
and 10°C may increase as storage duration in-
creases (
Fig. 15.2
). Storage below approxi-
mately 4°C also results in an increase in tuber
respiration rate compared with those stored
warmer (
5-
7°C). In
Fig. 15.2,
a large difference
in respiration rate is apparent between tubers
stored at 1.7°C and 4.4°C, regardless of time in
storage. A similar dependence of respiration
rate on temperature has been observed for
many cultivars (Schippers, 1977a).
Harvest operations and harvest damage can
have a large effect on tuber respiration rate dur-
ing the first weeks of storage, and as such can
increase dramatically the need for cooling air
during the initial storage period
(Fig. 15.3
). Res-
piration rates for cultivar Katahdin were
measured
1
or 11 days after tubers were hand
harvested, or after they had experienced one or
more mechanical harvest operations. Tubers
that had been windrowed, picked up with a
mechanical harvester, and piled into storage
had respiration rates twice those of tubers that
had been hand harvested. Each step in the har-
vest operation was additive: each contributing
to the final respiration rate
(Fig. 15.3
). Bruising,
skinning, dropping, and other mechanical stress-
es increase tuber respiration rates, which persist
for days or weeks (Schippers, 1977a; Burton, 1978;
Pisarczyk, 1982; Bethke and Busse, 2010).
Infection with pathogenic organisms leads
to an increase in the net respiration of stored po-
tatoes (Gwinn
et al
., 1989; Fennir
et al
., 2005).
The increase in tuber respiration is likely due to
the production of ethylene, exacerbated by the
infection (Creech
et al
., 1973; Gwinn
et al
.,
1989). Ethylene is a volatile plant growth regu-
lator that at very low atmospheric concentrations
(0.15 µl l
-
1
or less) stimulates potato tuber respir-
ation (Huelin and Barker, 1939; Reid and Pratt,
1972). At higher concentrations, ethylene can
