Low temperature responses of cacti: A review
Differences in distributional limits of various species of cacti caused by susceptibility to low wintertime temperatures can often be explained by the influence of differences in stem morphology on shoot temperatures. However, the tolerances of tissues to subzero temperatures, which vary considerably among cacti, must also be taken into account. During a low-temperature episode, supercooling of cactus stems below the tissue freezing point is followed by a temperature rise that represents the heat released during the formation of extracellular ice crystals. Future research will help elucidate whether the accompanying intracellular dehydration is responsible for the tissue death. Breeding and biotechnology programs to prevent freezing damage and thus to increase the cultivation of cactus species important for fruit, vegetable, and fodder production can then be undertaken in an informed manner.