Development of a simple growth model for light control in tomato seedling production

Abstract

Models are necessary for application of automatic control on any process in greenhouses. Despite the existence of several tomato crop growth models, no models are available for tomato seedlings. In the present paper, a simple empirical model was tested for the prediction of growth and development of tomato seedlings. Dry matter production, shoot length and leaf area were simulated as a function of incoming solar radiation, under different temperature regimes. In order to evaluate the model, experiments were conducted under various temperature and solar irradiance regimes. The experiments were carried out at the experimental farm of the University of Thessaly near Volos (Velestino, Thessaly), situated on the continental area of Eastern Greece, during three periods (winter, spring and late spring). Three light intensity levels were tested in each experimental period, namely: control level (natural light level), 20% higher than the control light level (using HPS lamps) and 15% lower than the control light level (using a shading net). The calibration of the model gave satisfactory results and revealed that it could be used for prediction of seedling dry matter production, shoot length and leaf area, as a function of light intensity. The calibrated model can be used for optimal greenhouse climate control and crop growth optimisation through greenhouse microclimate management by designing and implementing a robust controller.