摘要
An automatic control system was developed for real time preparation and application of nutrient solution for soilless tomato production. The control strategy was based on transpiration estimates by the Penman-Monteith model and on leachate concentration by measurements of electrical conductivity. The performance of the fertigation system was evaluated during tomato cultivation in sand substrate under greenhouse conditions. The commercial crop yield was 4.74 kg m鈭? and the average total soluble solids of tomato fruits was 4.50 掳Brix. Water use efficiency for tomato crop cultivated with the developed control system was 17.94 kg m鈭?. To produce 1 kg of tomato fruits, 44.42 L of nutrient solution were necessary. The proposed system was efficient in adjusting the frequency of fertigation cycles and controlling the prepared nutrient solution concentration, minimizing environmental problems related to effluent disposal and contributing to economy of fertilizer and water resources.