The effects of slope and channel nutrient solution gap number on the yield of tomato crops by a nutrient film technique system under a warm climate

Abstract

Inadequate oxygenation of the nutrient solution (NS) in recirculating hydroponicsystems leads to root hypoxia in several plants as a result of low oxygen solubility,and this is most notable in warm climates. Hypoxia affects crop nutrient and waterabsorption and results in reduced crop yield. However, increased air supply to the NSserves as a source of oxygen for the roots. To evaluate the incorporation of oxygen into thesystem, we varied the slope of 14-m long containers from 2% to4%and applied zero, one,two, or three gaps of NS. The channel width measured 10 cm and was equidistant fromthe end points. The effect of the dissolved oxygen in the NS was measured by the productionof a tomato cultivar. The oxygen dissolved in theNS was 5%greater in the channelswith a 4%slope compared with those with a 2% slope. The channels that included the gapsincorporated a higher quantity of dissolved oxygen during cultivation. In the middle of theday, the available oxygenwas the limiting factor for the yield. The best resultswere obtainedwith a steeper slope, and gaps also improved the tomato yield. More rapid changes in NSwere associated with a higher quantity of dissolved oxygen.