Long-term climate and weather patterns in relation to crop yield: a minireview

Abstract

It is accepted knowledge that weather affects yields and climate dictates which crops will grow in a region. Specific weather events, such as drought or hail, that affect yield or quality, are known, as are the general climatic conditions required for groups of crops such as cool season vegetables or tropical crops. However, more precise information on how changes in long-term weather and climate influence the yield of specific vegetable crops is not available. Studies of yield over long periods have the advantage of reflecting the combined effects of numerous environmental variables, including climate effects on physiological stress, pests, and diseases. A study of yields of cool season vegetable crops in Ontario revealed that a decrease in yields is related to an increase in the number of hot days with maximum temperatures over 30 °C. A clear warming trend in Ontario weather is evident, beginning in the mid-1980s, with increasing numbers of hot days and more variable temperatures from year to year. Furthermore, yields of cole crops declined by 10% for every 10 d with temperatures >30 °C in the growing season. Several other studies on agronomic crops worldwide show reductions in yield resulting from warmer temperatures. For example, in a study of rice in the Philippines, yield was reduced by 10% for every 1 °C increase in minimum temperature during the dry season. Methods for evaluating long-term climate effects on crop yield are discussed.