In general, the form and function of living plants reflect a requirement to maximize their interaction with the environment in order to harvest more effectively the energy and materials they require (Corner 1964). Thus, fluctuations in the aerial environment exert a considerable effect upon the physiology of the plant and lead to initiation of a range of responses. Changes in temperature are known to exert a pronounced effect on the growth of plants, and hence upon their productivity (Ong & Baker 1985). Most temperate species spend the majority of their life at mean temperatures below the optimum for their growth, and there are marked genetic differences between plant species in their ability to tolerate nonoptimal temperatures (Pollock & Eagles 1988). This review summarizes some of the ways in which plants are known to sense and respond to temperature change and discusses the potential for improving growth and performance at nonoptimal temperatures. Discussion concentrates upon temperate grasses and cereals because of their suitability as experimental material and because of their economic importance. Consequently, this review is largely concerned with responses to low temperatures, but some responses of tropical cereals to high temperatures are also described.
