Low Storage Respiration Rates

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Low Storage Respiration Rates
Development of Sugarbeet Germplasms with Low Storage Respiration Rates L. G. Campbell
Nearly 75 percent of the sugarbeet (Beta vulgaris L.) crop
is stored in large exposed piles for up to 180 days. The
stored sugarbeet root is a living organism that obtains need­
ed energy from its own sucrose through normal respiration.
Respiration is responsible for 50 to 60 percent of the sucrose
loss during post-harvest storage (9). Losses during storage
frequently average 0.5 pounds sucrose per ton of beets per
day and may reach two pounds per ton under poor storage
conditions.
2.5
_
RESPIRA TION LOSS 2 .0
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1.5
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The actual amount of sucrose consumed by respiration is
influenced by a number of factors. Figure 1 shows the
general effect that temperature has on sucrose loss (7) and
provides justification for rather sophisticated attempts to
control storage pile temperatures (2,10). Respiration is a
heat-producing process and nondissipated heat will result in
increased respiration rates and the potential for rapid
development of storage rots. Respiration rates of sugarbeet
roots are also influenced by the level of mechanical damage
during harvest and piling . In general, respiration rates in­
crease each time the beets are subjected to a mechanical
operation (3). Scalping at harvest increases both respiration
rate and susceptibility to storage rotting organisms.
~o
°c
~.s
'­I/)
1.0
g
0. 5
Figure 1. Effect of temperature upon sucrose losses due to
respiration (7).
Varieties differ in storage respiration rate (1,6,8). Rapid
screening techniques have been developed and storage
respiration rate has been altered by selection (4). This article
describes the development of sugarbeet lines with low
storage respiration rates.
induced to flower, and produced seed for future selection
cycles. Initially, diverse sugarbeet germplasm sources were
evaluated for internal CO 2 concentration. The sources in­
cluded inbred lines from other USDA programs and the
USDA Beta vulgaris world collection. Lines selected for low
internal CO 2 concentration have been evaluated for vigor,
quality, and agronomic performance in replicated field trials.
SELECTION PROCEDURES
Selection for low respiration rate was accomplished by
measuring internal carbon dioxide (C0 2 ) levels of individual
sugarbeet roots (5) . Carbon dioxide (a by-product of
respiration) concentration increases as respiration rate in­
creases. Roots were grown under conditions similar to those
used in commercial production, manually harvested, wash­
ed, and stored at 40 0 F and high humidity for one month.
Individual roots were sampeld by removing a 3/ 8by 2lj2 inch
cylindrical core from a smooth surface of the root below the
crown (Fig. 2a) . The cavity was immediately sealed with a
rubber serum vial stopper (Fig. 2b) and the root was return­
ed to storage. After 48 hours an air sample was removed
with a needle and syringe (Fig. 2c). The CO 2 concentration
of the sample was measured with a differential infrared gas
analyzer. Roots with relatively low internal CO 2 concentra­
tions (low respiration rates) were planted in the greenhouse,
CHARACTERISTICS OF SELECTED LINES
Two germplasm lines with low storage respiration rates
have been jointly released by the USDA and the North
Dakota Agricultural Experiment Station. The lines have
been designated FI007 and F1008. They provide commer ­
cial breeders genetic material for incorporation of low
storage respiration rate into their breeding stocks.
F1007 is a multigerm, green hypocotylline selected from
a population formed by interpollinating low internal CO 2 in­
dividuals from 31 accessions of the world collection of Beta
vulgaris. Progeny of each selected plant were evaluated as a
family. Superior individuals from families with relatively low
Campbell is research ge neticist, Agricultural Research Service,
USDA, Fargo, North Dakota.
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•
PI 171515 and PI 176872. Both orinigated from Turkey. In­
ternal CO 2 concentrations of F1 007 were approximately 40
percent of those observed in the commercial hybrids KW
1132 and Beta 1230. Commercial hybrids d id not differ
greatly in internal CO 2 concentration.
F1008 is a multigerm, green hypocotyl line selected from
the same base population and in the same manner as
F1007. Internal CO 2 concentrations of F1 008 were usually
slightly higher than those of F1007 but still only about 50
percent of that observed in KW 1132 and Beta 1230. The
maternal parents of the selections used in the pair-cross that
resulted in F1008 were PI 1690 16 and PI 181716. PI
169016 originated from Turkey and PI 181716 from
Lebanon .
. Both lines have been evaluated in replicated trials for two
years at Fargo. Root yield of F1007 has been about equal to
adapted commercial hybrids; however, the sucrose concen­
tration was only about 70 percent of the hybrids. Purity per­
cent (the percentage of the total sucrose that can be ex­
tracted using standard factory methods) was about 4 percent
below the hybrids. F1008 yielded about 70 percent of the
check hybrids and was slightly lower than the commercial
checks for sucrose and purity percent. These lines are in­
tended to be used as pollinators for expe rimental hybrids. as
parents in genetic studies, and as genetic sources for the
development of parental lines with reduced sucrose loss due
to respiration. Low storage respiration rate is intended to
complement other methods of reducing storage losses such
as reducing injury to the roots and pile ventilatio n . Breeder
seed of F1007 and F1008 will be maintaine d by the USDA­
ARS sugarbeet research group at Fargo. Germpla sm quan­
tities may be obtained from the author.
REFERENCES
1. Akeso n, W.R. and J.N. Widner. 1981. Differences among
sugarbeet cultivars in sucrose loss during torage. J . Am .
Soc. Sugar Beet Techno!. 21:80-91.
2. Anon ymo us. 1985. Extending sugarbeet life through storage
facilit ies. Sugar Producer 11 (3): 10-11.
3. Cole, D.F. 1977. Effect of cultivar and mechanical damage
on respiration and storability of sugarbeet roots . J. Am.
Soc. Sugar Beet Techno!. 19:240-245.
4. Cole, D.F. 1980. Post-harvest respiration rates and int mal
CO 2 concentration in sugar beet roots. Can. J . Plant Sci.
60: 1489-1491.
5. Cole, D.F. 1986. Relationship between in te rn al CO 2 and respiration in selected Beta vulgariS L. genotypes. J. Am. Soc. Sugar Beet Techno!. 23: 116-120 . 6. Cole, D.F. and W.M. Bugbee. 1976. Genetic an d other fac ­
tors affecting internal CO 2 concentration in sugar beet roots .
Can. J. Plant Sci. 56:627-63l.
7. McG in nis, R.A. and D.L. Sunderland. 1971. Beet storage .
p. 91-1 06. In R.A. McGinnis (ed.) Beet- uga Techno logy.
2nd ed. Beet Sugar Development Fou ndation , Ft. Collins ,
CO.
8. Theurer , J. C ., R.E. Wyse, and D.L. Doney. 1978. Root
storage respiration rate in a diallel cross of sugarbeet. Crop
~
Sci. 18: 109-111.
9. Wyse R.E . and S.T. Dexter. 1971. Source of recoverable
sugar losses in several sugarbeet varieties during storage.
Am. Soc . Sugar Beet Techno!. 16:390 -398.
10. Wyse R.E . and R.M. Holdredge. 1982 . A comparison of
forced ventilation and natural convection as a means of
cooling sugarbeet storage piles in several geographic loca­
tions. J . Am. Soc. Sugar Beet Techno!. 21:235-246 .
Figure 2. Sampling technique for measuring relative storage
respiration rates (internal CO2 ); (a) core removed to form cavi­
ty, (b) cavity sealed with serum stopper, and (c) removal of air
sample with syringe.
internal CO 2 means were crosses in pairs. Three additional
cycles of selection within the lines formed by the pair crosses
followed. The mating procedure did not allow for determin­
ing if, or to what extent, selfing occurred during selection.
Concurrent with selection for low internal CO 2 concentra­
tion, visual selection was used to eliminate lines with the
tendency to produce sprangled or colored roots. The mater­
nal parents of the plants used in the original pair cross were
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