INFLUENCE OF FERTILIZATION ON YIELD AND QUALITY OF SPINACH (Spinacia oleracea L.) DURING STORAGE UNDER CONTROLLED ATMOSPHERE

The aim of the study was to examine the influence of nitrogen fertilization, mainly in the form of ammonium, containing the inhibitor of nitrification Dicyandiamide that delays the release of nitrogen into the soil, on optimal growth, yield production, and yield quality development of spinach as well as the suitability of spinach for storage compared with conventionally applied fertilizer. In addition to the influence of the applied kind of fertilizers, the dependency from the concentration of the fertilizer was studied. The experimental results revealed that the application of nitrogen in the form of Basammon-nitrogen resulted in a better color development of leaves, a higher content of chlorophyll and an in tendency higher crop yield compared with calcium-ammonium nitrate. Independent from the kind of fertilizer, the standard dose of 220 kg . ha(-1) N proved to be optimal. Excessive fertilization with 330 kg . ha(-1) N resulted in a decrease of sugar contents, enlarged concentrations of nitrate, and the decrease in taste values. At the same time it increased the costs for fertilization and the environmental risk due to rinsing of nitrates into the groundwater. A positive aspect was the more intensive color of leaves. The kind of fertilizer did not affect the suitability for storage of spinach. However excessive nitrogen caused greater losses of soluble carbohydrates during storage.