Lösch R, Kappen L
Botanisches Institut der Universität Kiel, Olshausenstr. 40-60, D-2300, Kiel, Federal Republic of Germany.
Oecologia. 1981 Aug;50(1):98-102. doi: 10.1007/BF00378800.
Cold resistance of twenty-seven species 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°C. Cold stress response was principially different: Cold resistance of about half 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 species). The other species developed tolerance to freezing, thus resembling the behaviour of the hardy Eurasian Sempervivum species. Several Aeonium and Monanthes species resist to reasonable 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 two 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.
对27种马卡罗尼西亚长生草亚科植物在凉爽但不过于严酷的条件下统一栽培时的抗寒能力进行了测定。所有受试物种的抗寒极限在-4℃至-10℃之间。冷应激反应主要不同：约一半受试物种的抗寒能力归因于冰点降低。这种反应类型，即避免结冰，其中叶片中的任何结冰都会导致伤害，在最抗寒的物种（匙叶莲花掌、几种爱染草属物种）中被发现。其他物种则对结冰产生耐受性，因此类似于耐寒的欧亚长生草属物种的行为。几种莲花掌属和魔南景天属物种能耐受比其自然栖息地通常出现的温度更低的温度。物种在抵抗冷应激方面的差异可能源于耐受细胞冻脱水的不同能力。长生草属类群很好地说明了两种耐寒进化策略：避免机制，如降低渗透势，是在有适度霜冻的高海拔地区定殖的物种的典型特征。然而，对于将分布区域扩展到有更严重霜冻的高纬度地区的物种来说，耐冻性是必要的。
