Carbohydrate storage and use in an alpine population of the perennial herb, Oxytropis sericea |
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Authors: | Tomasz Wyka |
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Institution: | (1) Division of Biological Sciences, 105 Tucker Hall, University of Missouri-Columbia, Columbia, MO 65211, USA e-mail: c624928@showme.missouri.edu, Tel.: +1-573-8827399, Fax: +1-573-8820123, US |
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Abstract: | I tested hypotheses for ecological roles of storage carbohydrates in perennating organs (roots and branches) of alpine Oxytropis sericea, a leguminous herb. In naturally growing plants, total nonstructural carbohydrates achieved their maximal concentration in
the fall, declined during winter, and reached minimal levels immediately after growth initiation in the spring. Experimental
manipulation of carbon sink-source relations through shading of leaves of reproductive plants revealed that the normally unused
portion of these carbohydrates is largely available for withdrawal. In another experiment, plants subjected to carbohydrate
depletion through shading suffered decreased leaf growth after winter dormancy and had a lower probability of flowering and
decreased inflorescence biomass. The dependence of reproductive growth on stored carbohydrates, however, was limited to its
initial stages, because accumulation of storage carbohydrates occurred simultaneously with inflorescence expansion, flowering,
and fruiting. Moreover, the whole-plant photosynthetic rate, estimated from gas exchange measurements also peaked at the time
of inflorescence growth. To address whether stored reserves allow compensatory regrowth following defoliation, plants were
subjected to experimental removal of leaves and inflorescences. Defoliated O. sericea partly regrew the lost leaves but withdrawal of stored carbohydrates was limited. Similarly, in a second defoliation experiment
where infructescences were left intact, the plants used little stored carbohydrate and only partly compensated for fruit growth.
However, carbohydrate accumulation was negatively affected by defoliation. While the ecological importance of stored nonstructural
carbohydrates cannot be attributed to any function in isolation, winter respiration, leaf regrowth after winter, and early
reproductive growth in O. sericea all depend to a significant extent on stored reserves. Maintaining a large storage pool may protect these functions in years
when carbon status is less favorable than during this study.
Received: 13 May 1998 / Accepted: 24 November 1998 |
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Keywords: | Carbohydrate storage Allocation Defoliation Oxytropis sericea Perennial plants |
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