NUTRITIONAL DYNAMICS AND YIELD OF CUCUMBER GROWN IN HYDROPONICS WITH AND WITHOUT RECIRCULATION OF THE NUTRIENT SOLUTION

A common problem in hydroponics systems in which the nutrient solution is recirculated (closed systems) is a lower yield and quality over systems without recirculation (open system), which is attributed to imbalances of nutrient solutions and to an increase in the risk of spread of root diseases as the crop is developing. This research evaluated the possibility of closed hydroponic systems to achieve cucumber (Cucumis sativus L.) yields similar to those obtained with open systems, by shortening the growing cycle. Three types of closed systems (floating hydroponics, cultivation in bed with substrate and cultivation in bag with substrate) and two open systems (culture in bag and in bed with substrate), were compared under a complete randomized block design with five replications. It was found that both plant growth and fruit yield of cucumber were similar between closed and open systems in bag and bed, but with floating hydroponics a higher dry matter accumulation and yield per unit area were reached. Closed systems allowed savings of over 20% in water and 25% in nutrients compared to open systems.