Date of this Version
Arkebauer, "Leaf Radiative Properties and the Leaf Energy Budget, Micrometeorology in Agricultural Systems", Agronomy Monograph no. 47
Leaf radiative properties are the physical properties of leaves that characterize radiant energy exchange with their surroundings. Radiant energy exchange is an important consideration in studies of plant function since, for example, absorption of photosynthetically active radiation (PAR) leads to the transformation of this energy into chemical energy via photosynthesis. Thus, plant productivity, and hence, agricultural production, ultimately depend on leaf radiative properties.
Leaf temperature is an additional, very important, parameter in intimate association with leaf radiant energy exchange. This association occurs since energy gained via radiation must be in balance with energy lost through various processes and energy loss from the leaf is predicated on leaf temperature. Leaf temperature is a critical factor determining leaf transpiration (hence, crop water use), reaction rates of biochemical processes (hence, photosynthetic rates, respiration rates, growth rates and productivity), and many other aspects of plant function. Thus, leaf radiative properties not only affect leaf radiant energy exchange but are implicit in determining rates of plant C uptake and water loss.
This chapter will begin with an overview of leaf radiative properties. Next will follow a description of the significance of leaf radiative properties in determining the leaf energy budget. Leaf temperature will be discussed as the key component in characterizing energy interactions with leaves and their environments and a practical technique for determining the leaf temperature from the leaf energy budget will be presented. Finally, the importance of leaf conductances in the solution of the leaf energy budget will be stressed. Although much of the research cited will be focused on species of agronomic importance the general discussion is appropriate for foliage elements of any plant species.