Effect of energy saving solar sleeves on characteristics of hydroponic tomatoes grown in a greenhouse

• Yield and quality of tomato crop were examined in a heated greenhouse.
• Tomato plants were cultivated hydroponically on top of water filled solar sleeves.
• Solar sleeves improved the microclimate at the level of the tomato plants.
• Optimised temperatures led to higher marketable fruit number, mean weight and yield.
• Fruits on solar sleeves presented higher antioxidant activity by 18.4%.

A research project was conducted during winter period, to investigate the effect of a hybrid solar energy saving system (HSESS) on yield and quality of hydroponically cultivated tomatoes in a heated greenhouse. Water filled transparent cylindrical polyethylene sleeves along with peripheral perforated air filled tubes consisted the solar energy storage system which was installed in one part of the greenhouse. There, the tomato plants were cultivated on the sleeves and between the peripheral tubes which acted also as a gutter for the drainage of the excess nutrient solution (experimental treatment). A second part of the greenhouse (control treatment) operated only with conventional heating and the tomato plants were placed on plastic gutters. The use of the hybrid solar energy saving system in the experimental treatment improved the greenhouse microclimate, compared to the control one, leading to higher marketable and total yield by 10.8% and 7.1%, respectively. Moreover, the tomatoes on the HSESS presented significantly higher marketable fruit number and mean weight by 6.8% and 3.6%, respectively and increased antioxidant capacity levels by 18.4%.