Investigations on the Variability of Heat-Resistance in Plants

Survival types of high mountain plants under extreme temperatures

“…The annual course of heat resistance of vascular plants is not only synchronised with the climatic conditions but also endogenously and species-specifically determined (Kappen, 1981;Lange, 1967). There are species which show an increase in resistance during summer (S-type), species which develop increased heat resistance during winter dormancy (W-type) and finally species which hardly show any annual fluctuations in resistance at all (C-type).…”

Responses to Extreme Temperatures. Cellular and Sub-Cellular Bases

“…Seasonal fluctuations in heat hardiness are usually characterized by two peaks in resistance which occur in the winter and summer with maximal resistance in winter (LANGE 1967). Increased thermal tolerance can be elicited by cultivation at temperatures for several weeks or months (LANGE 1967;PEARCY et al 1977), but species differ in their capacity for thermal acclimation . In species capable of thermal acclimation, an increased thermostabi1ity of both the thy lakoid membranes and an unidentified extra-thylakoid soluble protein is observed .…”

“…The thermal tolerance of plants, while characteristic for a species, is not constant (LANGE 1967) and varies with the stage of development, age of the organ in question, and exhibits both seasonal and diurnal variation (LARCHER 1973), for detailed discussion see Chapter 14, this Volume. Seasonal fluctuations in heat hardiness are usually characterized by two peaks in resistance which occur in the winter and summer with maximal resistance in winter (LANGE 1967).…”

Genetic Engineering of Osmoregulation

“…In fact, Lange (1967) does not subscribe to Levitt's proposal (1958) that there is a "clear cut parallel between frost, drought, and heat tolerance" and that the general increase in resistance is caused by a single protoplasmic factor --most notably the sulfhydryl-disulfide hypothesis (Levitt, 1962), which has been extensively invoked in all forms of stress resistance . Lange (1967) cites examples where the relation between heat-and frost-resistance occurs only periodically in most investigated species and is even totally absent in others. Similarly, while Santarius (1973) considered certain similarities between frost, desiccation, and heat resistance, he acknowledged that they do not always change in parallel.…”