Storage and mobilization of nonstructural carbohydrates and biomass development of beech seedlings (Fagus sylvatica L .) under different light regimes |
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Authors: | D Gansert Werner Sprick |
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Institution: | Lehrstuhl für Geobotanik, Universit?t G?ttingen, Untere Karspüle 2, D-37073 G?ttingen, Germany, DE
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Abstract: | Beech seedlings were grown under 8%, 13%, 23% and 100% relative light intensity for 2 years after germination. Starch, sucrose
and monosaccharides from the bark and wood parenchyma of shoots and roots were analyzed during the course of the second year.
The annual allocation pattern of starch revealed five successive phases: starch disintegration in November (1) was paralleled
by high monosaccharide concentrations in the shoot cortex (≤ 33.4 mg/g DW). Seedlings of all light variants reached maximum
sucrose concentrations (≤ 82.8 mg/g DW) during starch disintegration in January (2) that coincided with decreased monosaccharide
contents. Up to mid-April, resynthesis of starch (3) occurred in most shaded and unshaded seedlings. In May, starch was converted
into monosaccharides in all storage tissues (4). Seedlings grown under 13% light intensity showed de novo synthesis of starch
(5) 4 weeks after bud burst. These seedlings reached 98% maximum starch storage capacity of the shoot and 89% of the root
in July. In mid-October, the maximum starch concentration of the roots increased with light intensity, and this corresponded
with an increase of lateral root growth. The variation of shoot and root dry weight was closely related to the content of
nonstructural carbohydrates during the second year. The shift of shoot growth to the first half of the growing season and
the suppression of lateral root growth during the second half is assumed to be a strategy of young beech to survive under
light limiting conditions.
Received: 22 May 1997 / Accepted: 10 October 1997 |
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Keywords: | Fagus sylvatica Light Growth Carbohydrates Starch |
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