INFLUENCE OF FERTILIZATION TREATMENTS ON NITRATES CONTENT OF SOME VEGETABLE SPECIES CULTIVATED IN THE FIELD

Abstract

The existing amount of nitrates in plant at a given time is the result of balance between the amount absorbed and used in protein-genesis. A main cause of nitrate accumulation in vegetables is the use of nitrogenous fertilizers on crop land. High concentration of nitrates in plants (especially in vegetables) means a hazard for human and animal body, for two reasons: possibility of methemoglobin appearance at children and nitrates conversion to nitrites in saliva and formation of cancerigen nitrosamines in the intestinal tract. This paper presents the results of researches made in order to establish the influence of fertilization treatments on nitrates content of some vegetable species, cultivated in the field: egg plants, green peppers, bell peppers and carrots. In the culture technology of these vegetables, the following fertilization variants were applied (fertilizer being ammonium nitrate with 33% nitrogen): V1 = 0 kg nitrogen/ha; V2 = 100 kg nitrogen/ha; V3 = 200 kg nitrogen/ha; V4 = 400 kg nitrogen/ha; V5 = 800 kg nitrogen/ha. In order to establish the accumulation potential of nitrates in vegetables cultivated in the field, an enzymatic method was used. When no fertilizer was added in the culture, bell peppers had the minimum value of the nitrates content (11.53 mg NO₃^-/kg), and carrots the maximum one (90.42 mg NO₃^-/kg). In the case of the highest fertilization level, carrots had the highest nitrates content (391.20 mg NO₃^-/kg), and bell peppers the lowest one (63.08 mg NO₃^-/kg).