A potato growth and production model

Graduation date: 1986A potato plant growth and production model is developed with\ud the objectives of analyzing management alternatives and exploring\ud the nature of the early dying syndrome. The geographic area of\ud focus was the centerpivot irrigated circles of Oregon's Columbia\ud Basin. A problem analysis of the potato production system of this\ud area, and review of existing potato growth models, indicated the\ud need for a physiological process model at the resolution of one day.\ud Model behavior is a result of the daily integration of physiological\ud processes organized into subsystems whose activity results from\ud environmental and management inputs intergrated with the current\ud state of the plant.\ud The model is based on a general theory of plant growth. Field\ud observations, during the 1983 and 1984 growing seasons, were used to\ud parameterize and confirm model behavior. The range of management\ud practices in the area and associated behaviors of plant growth are\ud summarized. Five sets of hypothetical plant growth trajectories\ud based on the observed data were used to couple field observations\ud with model behavior. The effect of abiotic and biotic stressing\ud agents on plant growth are studied by modifying known physiological\ud mechanisms. Hypothetical model structures were used when observed\ud or hypothesized plant behaviors could not be modelled as resulting\ud from known mechanisms. A physiological adaptation subsystem is\ud hypothesized and developed for this purpose. The subsystem of\ud physiological adaptation and its theoretical foundation was\ud stimulated by and follows the approach of work in animal stress by\ud Selye (1946,1952,1976). The concept of general adaptation and\ud maintainance of functional homeostasis in plants is used to explain\ud hypothesized but unexplained behaviors. The benefits of considering\ud a maladaptation perspective of disease is discussed