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On the role of orientation in reducing photoinhibitory damage in photosynthetic‐twig desert shrubs
Author(s) -
EHLERINGER J. R.,
COOPER T. A.
Publication year - 1992
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1992.tb00977.x
Subject(s) - photosynthesis , twig , quantum yield , botany , yield (engineering) , biology , physics , quantum mechanics , fluorescence , thermodynamics
Quantum yields for O 2 evolution were measured in photosynthetic twigs and leaves of Hymenoclea salsola and Senecio douglasii , two common shrubs of the deserts of western North America. When exposed to long‐term drought, quantum yields of leaves and twigs remained constant up to the point of leaf abscision in both species. As water stress developed further, quantum yields began to decline in twigs; the extent of this quantum yield reduction was dependent on incident photon flux density. The reduction in quantum yield in twigs, which have a near‐vertical orientation, was greatly accelerated when twigs were reoriented to the near‐horizontal inclination typical of leaves. The reductions in quantum yield were not rapidly reversible and are interpreted as indicating photoinhibitory damage. The results are discussed in terms of the role that a near‐vertical orientation might serve in maintaining photosynthetic structures through a drought period.