Irrigação automatizada com déficit controlado em alface em ambiente protegido: produção em vasos e em bandejas

Abstract

The concern with the intensive use of natural resources has become increasingly justifying the development of new technologies aiming their rational use such as automated irrigation systems. The automation of irrigation could to allow water saving increasing efficiency of its use in agricultural production. The first chapter of this study was to evaluate five different volumes (130, 100, 80, 60 and 33% of volume of Simplified Irrigation Controller - SIC) in the production of lettuce in pots in a production system called "Organic Potponics". It was used the SIC, whose operation is based on tension in the soil solution. The different volumes were achieved by drippers association of different flow rates in the same pipe. It was evaluated fresh and dry weight, number of leaves and diameter of lettuce plants (production variables); stomatal conductance, chlorophyll content, relative water content in leaves and chlorophyll fluorescence (physiological variables); and the water use efficiency (WUE). The corresponding volume 126% specified by the SIC installed to a tension soil of 6 kPa was that provided the best results production of dry weight, whereas the maximal WUE was obtained for the corresponding slide 80%. It indicates the volume of 83%, because it provided the best economy of water and a satisfactory production to sale. In the second chapter aimed to evaluate the use of the SIC under four different tensions to the substrate for the production of lettuce seedlings in trays under greenhouse conditions. It was evaluated fresh and dry weight of shoots, number of leaves, shoot height, leaf length and leaf area (production variables); chlorophyll content (physiological variable); and WUE. Higher water stress in the substrate decreased irrigation events, harming the growth of linearly seedlings and causing large percentage of deaths. The tension of 4 kPa was the one that provided the highest values in all production variables. The tension of 6.5 kPa despite having a percentage of death, can be used to produce more resistant seedlings