Induction of Chilling Tolerance by Brief Abiotic Shocks

Abstract

Exposure to nonfreezing temperatures below ç12°C causes a physiological disorder called chilling injury in most crops of tropical origin (e. g., banana, mango), in some crops of subtropical origin (e. g., cucumber, tomato) and in a few crops of temperate origin (e. g., some apple cultivars, asparagus) (Bramlage, 1982; Couey, 1982; Saltveit and Morris, 1990). After a lag period of a few hours to weeks, during which chilling does not appear to have a permanent effect, the degree of injury increases proportionally with the duration of exposure and inversely with the temperature. Symptoms of chilling injury can develop at the chilling temperature (e. g., blackening of banana peel), but most symptoms only become obvious after stressed tissue is removed to a warm, nonchilling temperature. These symptoms include reduced seed germination, plant vigor, stand establishment, plant growth, quality, and shelflife of harvested commodities. Chilling injury can also include abnormal ripening and an increase in respiration and ethylene production, disease susceptibility, ion leakage and water loss. While most organs and tissues of a chilling sensitive plant exhibit some of these symptoms, certain sensitive plants (e. g., sweet corn) have parts (i. e., corn kernels and cob) that are insensitive to chilling.