Conclusion
The continuous increase of carbohydrate content in the rhizome in all treatments
suggested that storage compounds are continuously translocated to different parts of the
rhizome until November, irrespective if the fern was removed early or not.
Since the total content of carbohydrates was not significantly reduced compared with the
non-treated control, it seems likely that early fern removal at the end of September might
not have a negative effect on the yield of the following year. The latter should be
confirmed in future experiments.
Distribution of carbohydrates in the rhizome of asparagus (Asparagus officinalis L.) during progressing fern senescence in autumn
This study investigated the distribution of carbohydrate fractions in storage roots and rhizome buds during progressing fern senescence of asparagus and how this would be affected by an early fern removal at end of September. The early removal of the fern would be advantagous for technical and plant health reasons.
Carmen Feller & Anja Müller; Leibniz-Institute of Vegetable and Ornamental Crops [email protected] Theodor-Echtermeyer-Weg 1, D 14979 Großbeeren, Germany
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25
30
35
40
45
50
55
60
22.08.16 05.09.16 19.09.16 03.10.16 17.10.16 31.10.16 14.11.16
Control treatment (without fern cut)
pre-senescene fern removel September 21th
Carbohydrate fractions in rhizome buds and storage roots during senescence
Irrespective of the date of fern removal, in rhizome buds the content of saccharose has
continously increased by 30% with progressing senescence until the complete die-back of
the fern, while the content of other measured carbohydrates remained stable (fig. 1). In
storage roots the relative proportion of the carbohydrate fractions to each other did not
change much (fig. 2), but Brix-value (data not shown) and the content of inulin (fig. 2)
were increased with progressing senescence. This trend was also measured in 2015,
irrespective of the date of fern removal. Since the content of carbohydrates was similar
for Gijnlim and Rhapsody, results are shown as means of both the cultivars (fig. 1-4).
Effect of early fern removal
The content of root dry matter was similar in all treatments (data not shown), the total
number of rhizome buds was by trend lower in treatments with early fern removal
(102±20) compared with the control (146±33). Subsequent to the removal of the fern
in September, the content of all measured carbohydrate fractions in the storage roots was
temporary decreased but increased thereafter up to a level similar as in the control
treatment (figs. 3 and 4).
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40
60
8th Sept. 27th Sept. 11th Oct. 25th Oct. 8th Nov. 21th Nov.
Rhizome with storage roots
Rhizome buds
Carbohydrate fractions in rhizome buds (g / 100 g dwt)
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35
40
45
50
55
60
22.08.15 05.09.15 19.09.15 03.10.15 17.10.15 31.10.15 14.11.15
Control treatment (without fern cut)pre-senescene fern removel September 21th
0
20
40
60
8th Sept. 27th Sept. 11th Oct. 25th Oct. 8th Nov. 21th Nov.
New fern
Spears (yield)
Following year
Fern
Results
Carbohydrate fractions in storage roots (g / 100 g dwt)
Material & methods
Seedlings of the cultivars Gijnlim and
Rhapsody were planted 2012 into a field in
Großbeeren with a soil classified as sandy
soil. The distance between rows was 2 m
and between plants within a row 33 cm (cv.
Gijnlim) or 20 cm (cv. Rhapsody). Each
treatment had 4 replicates (rows) with 4
plants each. In one treatment the still green
fern was removed early on 21st or 26th
September, while in another treatment the
fern remained at the plant until November.
During plant growth the carbohydrates
inulin, fructose, glucose and saccharose as
well as the Brix-value were measured at 14-
day-intervals from end of August until
November 2015 and 2016. By end of
November in both years the rhizomes
including rhizome buds and storage roots
were harvested, then storage roots were
separated and freeze dried before analysing
their content of carbohydrates. In 2016 the
analyses also included the rhizome buds.
8th 27th 11th 25th 8th 21th September October November
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16
Carbohydrate content in storage roots (mg g-1 dwt) 2015
8th 27th 11th 25th 8th 21th September October November
5th 19th 3th 17th 31st 14th September October November
5th 19th 3th 17th 31st 14th
Carbohydrate content in storage roots (mg g-1 dwt) 2016
September October November
Fern remained (control) Early fern removal at 21st September
Fern remained (control) Early fern removal at 26th September
Fig. 1
Fig. 2
Fig. 3
Fig. 4
Mea
n ±
SE
Inulin
Fructose Glucose
Saccharose