Amelioration of an open soilless cultivation system for microgardening spinach (Spinacia oleracea L.)

The objective of this study was to develop an open soilless culture system with high water and nutrient use efficiency, and low emission in the environs for microgardening high quality spinach. For this purpose, spinach (Spinacia oleracea L.) was grown in containers with soilless media supplemented with organic and inorganic nutritional sources. The experiment was laid out in a complete randomized design with four replications. Seven growing media were assessed: peat moss, peat moss combined with 150, 200 and 250 ppm ammonium nitrate (NH4NO3), and peat moss amended with compost having nitrogen equivalent to the mentioned NH4NO3 concentrations. Scheduled and quantified irrigation was provided with a sprinkler system to conserve water and minimize emission into the environment. Salt accumulation and pH of media was monitored throughout growing period. Spinach leaves were analyzed for total soluble solids, titratable acidity, ripening index, total nitrogen, total organic carbon, carbon to nitrogen ratio, fresh biomass, dry biomass, dry matter (mg g(-1) fresh biomass), leaf moisture contents, nitrate content, colorimetric traits (lightness, chromacity and hue angle), ascorbic acid, total flavonols and anthocyanins and antioxidant capacity. Among all media, combinations of peat moss with NH4NO3 resulted in less nitrate, more organic carbon and dry matter (mg g(-1) fresh biomass), higher total soluble solid contents and ripening index of the plants. A higher flavonoid content and higher antioxidant capacity were also observed in plants grown in these combinations. Further, these media accumulated less salt and maintained optimum pH level for spinach growth.