Abstract
The research was conducted from April to September 2016, at the Fabio Baudrit Moreno Agricultural Experimental Station of the University of Costa Rica, Alajuela, Costa Rica, with the Costa Rican hybrid of sweet pepper ‘Dulcitico’, in hydroponic system under greenhouse. The effect of 2 planting densities (1.4 and 2.4 plants.m-2) and 3 volumes of substrate (7, 14 and 21 L.plant-1) on the yield, total available water content (ATD) in the substrate, drainage, crop evapotranspiration (ETc) and water use efficiency (EUA) were evaluated. A design of 3 complete blocks at random with a factorial arrangement of 2 x 3 treatments was used. The ETc was obtained by water balance in the substrate and the EUA as a result of the ratio between yield and ETc. For all the response variables, no different trends were observed between the two planting densities, as the substrate volume was increased from 7 to 21 L (p<0.05). Both factors affected (p<0.05) independently all the variables; except the ATD and yield, which were only affected (p<0.05) by the volume of substrate and plant density, respectively. In all cases, the effect of greater magnitude was due to the density factor. The volume of substrate did not affect the yield, however, it contributed to improve the EUA by reducing the volumes of irrigation, ETc and drainage. Higher planting density increased yield (kg.m-2), but reduced the EUA due to higher water consumption (ETc) and higher volumes of irrigation, ATD and drainage. The highest EUA was obtained at 1.4 plants.m-2 and 7 L of substrate.plant-1, due to a reduction of 13% in the ETc with respect to the crop with 21 L of substrate.plant-1 and 2.4 plants.m-2.
Keywords: Irrigation management; substrate water content; planting density; substrate volume.