Section 7
Chapter 6,617

The cold resistance of macaronesian sempervivoideae

Loesch, R.; Kappen, L.

Oecologia (Berlin) 50(1): 98-102


ISSN/ISBN: 0029-8549
DOI: 10.1007/bf00378800
Accession: 006616536

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Cold resistance of 27 spp. of Macaronesian Sempervivoideae uniformly cultivated under cool moderate but not hardening conditions was measured. The resistance limits of all the tested species ranged between -4 and -10.degree. C. Cold stress response was principally different. Cold resistance of .apprx. 1/2 of the tested species was due to freezing point lowering. This response type, avoidance of freezing, in which any ice formation in the leaves leads to injury, was found in the most cold-resistant species (Aeonium spathulatum, several Aichryson spp.). The other species developed tolerance to freezing, thus resembling the behavior of the hardy Eurasian Sempervivum spp. Several Aeonium and Monanthes spp. resisted reasonably lower temperatures than normally occur in their natural habitats. The species-specific differences in resisting cold stress may originate from different abilities to tolerate cellular freeze dehydration. The Sempervivum alliance illustrates well the 2 evolutionary strategies of cold tolerance. Avoidance mechanisms, like lowering the osmotic potential, are typical for species colonizing higher altitudes with moderate frosts. For species extending their distribution area into higher latitudes with more severe frosts, however, freezing tolerance is necessary.

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