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Freezing avoidance in Andean giant rosette plants
Author(s) -
RADA F.,
GOLDSTEIN G.,
AZOCAR A.,
MEINZER F.
Publication year - 1985
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.1365-3040.1985.tb01685.x
Subject(s) - pith , supercooling , rosette (schizont appearance) , ice formation , frost (temperature) , botany , freezing point , parenchyma , biology , geology , meteorology , atmospheric sciences , physics , geomorphology , immunology , thermodynamics
Frost avoidance mechanisms were studied in Espeletia spicata and Espeletia timotensis , two Andean giant rosette species. The daily courses of soil, air and tissue temperatures were measured at a site at circa 4000 m. Only the leaves were exposed to subzero temperatures; the apical bud and stem pith tissues were insulated by surrounding tissues. The leaf tissues avoided freezing by supercooling rather than by undergoing active osmotic changes. The temperatures at which ice formed in the tissues (the supercooling points) coincided with injury temperatures indicating that Espeletia tissue does not tolerate any kind of ice formation. For insulated tissue (apical bud, stem pith, roots) the supercooling point was around ‐ 5°C coinciding with the injury temperature. Supercooling points of about –13 to ‐ 16°C were observed for leaves. These results contrast with those reported for Afroalpine giant rosettes which tolerate extracellular freezing. The significance of different adaptive responses of giant rosettes to similar cold tropical environments is discussed.