Comparison of open and combined closed hydroponic system on water productivity, nutrient use efficiency yield and fruit quality of cucumber

One of the greatest challenges currently facing society is the production of high-yield and high-quality foods due to population growth and the need to increase food production. In this study, the effect of two hydroponic systems on water productivity,</strong> </strong>nutrient use efficiency yield and fruit quality </strong>of three greenhouse cucumber cultivars have been investigated. This experiment is in the form of split plots in a randomized complete block design, with the treatment of cucumber cultivars (</strong>Strong, Yalda, and RY) and type of hydroponic cultivation system (open and combined </strong>closed) in which 3 replicates were implemented at Shahid Chamran University of Ahvaz.</strong> The studied traits included water productivity,</strong> </strong>nutrient use efficiency, crop yield, </strong>fruit length and diameter, fruit volume, fruit firmness, fruit dry weight, fruit carotenoids, phenolic compounds, total soluble solids, titratable acidity were measured. The highest fruit length, fruit diameter, yield, water productivity and nutrient use efficiency were obtained in the combined closed system. The highest fruit firmness, total soluble solids, phenolic compounds were obtained in the open system. The combined closed system increased crop yield, water productivity and nutrient use efficiency by 22.63%, 80.81% and 81.92 % respectively, as compared to the open system. The highest phenolic compounds, fruit length, yield and water productivity were calculated in the RY cultivar. The RY cultivar increased phenolic compounds by 56.30% and 71.98% respectively, as compared to the Strong and Yalda cultivars. Based on the results, Fruit diameter had a significant correlation with fruit length (0.47*</sup>) and crop yield (0.55*</sup>). According to the results of this study, combined closed system and RY cultivar have the highest quality characteristics of fruit and yield, therefore they can be recommended for greenhouse production.</strong>