Helga Pien

MODELING DYNAMIC BEHAVIOR OF LEAF TEMPERATURE AT THREE-DIMENSIONAL POSITIONS TO STEP VARIATIONS IN AIR TEMPERATURE AND LIGHT

Organisms such as plants grow as a result of the influence of their genetics and microenvironment, consisting of physical, chemical, and biological factors. The microenvironment or microclimate is the environment closely surrounding these organisms and varies in time and space. To control processes more optimally, it is necessary to understand how living organisms respond dynamically to their physical microenvironment. Most models being developed to explain this relationship through steady-state models are descriptive (deterministic) and too complex to be used for control purposes. Therefore, it is attempted in this work to develop a dynamic black box model. For this study only air temperature was considered in 3-D (three dimensions). The objective of this research was to model the dynamic response of leaf temperature to time variations in air temperature closely surrounding that leaf, and to light-dark alterations. This biosystem is modeled using an ARX model structure (black box). Three-dimensional gradients in air temperature around the plant were shown and analyzed. It is demonstrated that a complex process such as the response of leaf temperature to changes in 3-D ambient air temperature and light-dark alterations can be modeled with a mean r 2 between 92.7% and 99.9%.