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 feller@igzev.de Theodor-Echtermeyer-Weg 1, D 14979 Großbeeren, Germany

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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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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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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

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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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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