Abstract
This paper presents applications of a‘speaking plant’-based intelligent control technique to dynamically optimize hydroponic cultivation and fruit-storage processes. Tomato growth during the seedling stage was optimized by nutrient concentration of a hydroponic solution in a cultivation process. Similarly, for the storage process, the rate of water loss in tomatoes was minimized by temperature control. The control system comprises a decision system and a feedback control system. The former is used for determining the optimal set point profile (l-step set points) of the environment based on plant responses, whereas the latter controls the environment based on the optimal set point profile. The optimal set point profile of the nutrient concentration of the solution during the seedling stage was a slightly high level (1.4mS/cm) during the first few days, a markedly low level (0.3mS/cm) during the second few days, a slightly high level (1.6mS/cm) during the third few days, and the maximum level (2.0mS/cm) during the last stage (flowering stage of the first truss) under the range of 0.3 to 2.0mS/cm. This operation promoted reproductive growth of the tomato. In the storage process, on the other hand, the optimal temperature operation that first rises to a high level (40°C) for a day and then suddenly drops to the minimum level (15°C) under the range of 15 to 40°C provided lower values of the rate of water loss than when the temperature was maintained constantly at the lowest level throughout the entire control process. These results suggest that dynamic optimization using a speaking plant-based intelligent control technique is useful for qualitative improvement of both the plant during cultivation and the fruit during storage.
