LOW-TEMPERATURE STRESS IN FIELD AND FORAGE CROP PRODUCTION – AN OVERVIEW

Abstract

Low temperature is a major constraint to the productivity of field crops. It is likely to remain so even in the event of increasing global temperature, because to maximize economic potential producers will tend to use the longest season crops compatible with average weather conditions. Low temperature in the growing season may reduce germination, may retard vegetative growth by inducing metabolic imbalances and can delay or prevent reproductive development. Chilling temperature can damage the tissues of sensitive plants while freezing temperature will damage most tissues during active growth. Low temperature during the winter season may cause the death of overwintering crop plants during their dormant phase. The overwintering habit in most crops results in higher yields due to the abundance of early spring moisture available to the crop. Death of plants may occur during winter by cell membrane disorganization during severe freezing exposure, by anaerobic stress due to flooding and ice encasement, by heaving of plants from soil by the formation of ice lenses, or by the activity of low temperature pathogens under snow cover. Environmental modifications to alleviate cold stress are only practical in a limited number of situations. Genotypic modifications are being made in many field crops to increase their tolerance to cold.Key words: Cold, freezing, chilling, winter survival