Effects of hydroponic systems on yield, water productivity and stomatal gas exchange of greenhouse tomato cultivars

The consumption of nutrient solution is very important in the production of vegetables, especially tomatoes. In this study, the effect of two hydroponic systems on yield components, nutrient solution efficiency, and stomatal gas exchanges of two greenhouse tomato cultivars have been investigated. This experiment is in the form of split plots in a randomized complete block design, with the treatment of tomato cultivars (V4-22 and Amira) and type of hydroponic cultivation system (open and closed) in which 3 replicates were implemented at Shahid Chamran University of Ahvaz. The studied traits included crop yield, fruit number, fruit weight, cluster weight, nutrient solution efficiency, and stomatal gas exchanges (net photosynthesis rate, stomatal conductance, transpiration rate, intercellular CO2 concentration, and leaf temperature). The results showed that the effect of the hydroponic system had a significant effect on the efficiency rate of nutrient solution usage, the number of fruits, the weight of the third, fourth, and sixth cluster, stomatal conductance, transpiration rate, and leaf temperature. The highest number of fruits, stomatal conductance, transpiration rate, and leaf temperature were measured in the open hydroponic system. The highest and lowest rate of water productivity performance were obtained in the closed system (33.70 kg/m(3)) and open system (21.84 kg/m(3)), respectively. The closed system increased water productivity for yield and biomass by 54.3% and 42%, respectively, as compared to the open system. Whatsmore, the highest and lowest water productivity per biomass were obtained in the closed system (48.91 kg/m(3)) and open system (34.42 kg/m(3)), respectively. Tomato cultivars had significant differences in crop yield. The highest and lowest crop yields were measured in V4-22 cultivar (3874.29 g per plant) and Amira cultivar (3648.70 g per plant), respectively. Based on the results, the closed hydroponic system was superior in terms of water and fertilizer saving without a significant effect on crop yield due to the reduction of nutrient solution consumption up to 96% and fertilizer consumption up to 97%.