EVALUACIÓN DE DOS MÉTODOS PASIVOS DE OXIGENACION RADICULAR EN CULTIVO HIDROPONICO RECIRCULANTE DE TOMATE Y LECHUGA

Abstract

The inadequate oxygenation of the nutrient solution (NS) can produce root hypoxia in many plants, this fact affects the uptake of nutrients and water and its yield can be reduced. In cultures of Nutrient Film Technique (NFT) the system can produce hypoxia by the low solubility of oxygen in the NS, but it can work well oxygenated as a source of oxygen to roots. In order to evaluate the incorporation of oxygen by two passive methods, we studied the effect of slope at 2 and 4% in containers of 24 m in length and including the effect of rapidly varying flow of the NS, with zero, one, two and three drops of NS that produce hydraulic jumps. Dissolved oxygen was measured and variables of crop yield of tomato (Licopersicon esculentum Mill cv Pony Express) and lettuce (Lactuca sativa L cv Satine). Dissolved oxygen in the NS was always higher in growing lettuce compared with tomato. For lettuce the behavior of dissolved oxygen in the NS during the day was similar, the oxygen content in the NS did not differ in containers of 4% and 2% slope or by number of hydraulic jumps. The fresh weight yield of the shoots was greater for treatment with 4% slope and 3 hydraulic jumps. The root dry weight was also greater for this treatment. In tomato, the dissolved oxygen in the NS was greater in containers of 4% slope, there were also differences by the number of hydraulic jumps. At noon, when the oxygen content was lower, increased proportionally with the number of hydraulic jumps. The production yield of fruits was higher in the container with 4% slope, also had production increases with increasing hydraulic jumps. There is a correlation between the number of hydraulic jumps and the production of channels with 2% indicating that the limiting factor was oxygen. The results indicate that production of lettuce has no oxygen limitation in the treatments studied, while tomato production had the best channels with 4% slope, and three hydraulic jumps.