DEVELOPMENT OF PHOTOSYNTHESIS AND GROWTH MODELS OF SWEET BASIL AND ICE PLANT IN PLANT FACTORIES

Abstract

The objective of this study was to develop photosynthesis and growth mod-els of sweet basil and ice plant under plant factory environments. For photo-synthesis, biochemical models coupled with stomatal conductance and tran-spiration were considered. Saturation and compensation points of both plants for light and CO2 were determined by regression analyses of light and CO2 response curves, respectively. In the photosynthesis of sweet basil, non-rectangular hyperbola was the most suitable for The saturation and compensation points for light and CO2 were determined as 545.3, 26.5, 728.8 and 85.05 μmol·m-2·s-1, respectively, by the modified non-rectangular hyperbola model. The maximum carboxylation rate, potential rate of electron transport, and rate of triose phosphate utilization calculated by Sharkeys regression were 102.6, 117.7, and 7.41 μmol·m-2·s-1, respectively. The results showed that the coupled biochemical model was effective for predicting the photosynthesis of sweet basil leaves comparing to other descriptive models. For ice plant under plant factory environments, the saturation and compensation points for light and CO2 were 569.5, 56.02, 632.9, and 117.2 μmol·m-2·s-1, respectively. The maximum carboxylation rate, potential rate of electron transport, and rate of triose phosphate utilization were calculated as 222.3, 234.9, and 13.0 μmol·mol-1, respectively. The parameters of minimum stomatal conductance of water vapor at the light compensation point and empirical coefficient in the BWB model could be solved as 0.0487 and 0.0012, respectively. Finally, the growth models for temperature and CO2 concentration were developed by using an expo-linear model. Adequate air temperature and CO2 concentration for sweet basil and ice plant were 25oC and 800 μmol·mol-1, respectively. From this study, the coupled biochemical model was more effective for explaining the photosynthesis of sweet basil and ice plant during the juvenile stage under plant factory conditions.