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PHOTOSYNTHESIS AND CARBON ALLOCATION IN TIPULARIA DISCOLOR (ORCHIDACEAE), A WINTERGREEN UNDERSTORY HERB
Author(s) -
Tissue David T.,
Skillman John B.,
McDonald Evan P.,
Strain Boyd R.
Publication year - 1995
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1995.tb12658.x
Subject(s) - photosynthesis , biology , understory , evergreen , growing season , photosynthetic capacity , botany , deciduous , orchidaceae , ecology , horticulture , canopy
Seasonal patterns of photosynthesis and carbon allocation were determined for Tipularia discolor , a summer‐deciduous wintergreen orchid of the southeastern United States, to assess the effects of environmental conditions and leaf age on carbon acquisition and allocation patterns. There was no shift in the optimum temperature for photosynthesis ( T opt ) on a seasonal basis and T opt (≈26 C) was at least 10 C higher than daily maximum air temperature during most of the growing season. Lack of photosynthetic adjustment in Tipularia to seasonal fluctuations in temperature and light suggested that the photosynthetic characteristics of this wintergreen were more similar to those of spring ephemerals than to those of evergreens and summer‐active herbs. The decline in photosynthetic capacity during the winter growing season for Tipularia , largely due to leaf age effects, gradually reduced net photosynthetic rates in the field despite more favorable light and temperature conditions. Photosynthesis in the field was primarily limited by environmental conditions in early‐ and mid‐season and by photosynthetic capacity in late‐season. A 14 CO 2 labelling experiment demonstrated that patterns of carbon allocation to vegetative structures were affected by the season of photosynthetic carbon fixation, whereas reproductive structures received 21% of the recovered labelled carbon regardless of the period of labelling. Carbon acquired and stored during all periods of the growing season was used to produce new vegetative and reproductive structures.