Plant Energy Budgets: The Plant’s Energy Balance

Abstract

Temperature is a major environmental factor that determines plant distribution. It affects virtually all plant processes, ranging from enzymatically catalyzed reactions and membrane transport to physical processes such as transpiration and the volatilization of specific compounds. Species differ in the activation energy of particular reactions and, consequently, in the temperature responses of most physiological process (e.g., photosynthesis, respiration, biosynthesis). Given the pivotal role of temperature in the ecophysiology of plants, it is critical to understand the factors that determine plant temperature. Air temperature in the habitat provides a gross approximation of plant temperature. Air temperature in a plant’s microclimate, however, may differ substantially from air temperature measured by standard meteorological methods. The actual temperature of a plant organ often deviates substantially from that of the surrounding air. We can only understand the temperature regime of plants and, therefore, the physiological responses of plants to their thermal environment through study of microclimate and the plant’s energy balance.