Evolution changes in recirculating solutions in function of the nitrogen form application in Aglaonema commutatum 'Silver Queen' crop.

摘要

An experiment was conducted in a recycling system in a buried solar greenhouse in the Mediterranean area to determine the behaviour of different nutrient parameters in a recirculating solution through a plant. Aglaonema commutatum cv. Silver Queen was grown in a container with a diameter of 0.17 m filled with polyethylene balls as a substrate. The fertigation system included recirculation of the nutritive solution. The treatments were three concentrations of NO3-:NH4+: (T1) 6:0; (T2) 6:3; and (T3) 0:6 mmol/litre. The samplings were performed during two periods in winter and summer conditions. The samples were taken every 24 h for 20 days. The form of nitrogen generated important variations in the evolution of the recirculating solution and must be recognized to optimize the management of these systems. The contribution of NO3- form did not involve abrupt variations of the different nutrients parameters. Nevertheless, the contribution of NH4+ form generated the acidification of the recirculating solution. The pH of the recirculating solution was stabilized between 8 and 12 days, maintaining the values cited during the remainder of the period of sampling. An increment of the concentration of NO3- was observed and a decrease of the concentration of NH4+ was stronger in summer. It fits to emphasize the decrease of the concentration of HCO3- and CO32- in the recirculating solution in winter and its elimination in summer conditions are related to the variations of pH. This loss can involve abrupt oscillations of pH with possible losses of production. These modifications of the nutrients parameters of the recirculating solution can be owed to the nitrification process of NH4+..