SUMMARY
The accumulation of nitrates and nitrites in vegetables is directly influenced by the dosis of nitrogen-containing fertilizers used, the timing of fertilizer application, the light intensity which is important especially for plants cultivated under protection, the daytime temperature, the lack in oligoelements, that take part in the enzymes activity and the presence of some small amounts of nitrate reductase in plants.Even though the nitrates have a low toxicity, in higher amounts (over 10g in one dosis) can produce digestive disorders (nausea, eructations, internal bleeding).Although the nitrites can be found in small amounts in food, they are much more toxic. Children are the most sensitive at the nitrites toxic activity.Lettuce and spinach, cultivated under protection, can accumulate an excess of nitrates and nitrites, as a result of inadequate technological measures, surpassing the dosis accepted by the present legislation.In this experiment, the level of nitrates and nitrites in lettuce cultivated in unheated greenhouses, foliar fertilized with Ferticare, at different concentrations and various nitrogen content of the fertilizer, have been studied.Nitrates and nitrites concentrations lie between 295,2 mg/kg to 444,7 mg/kg for nitrates and 6,4 mg/kg to 10,5 mg/kg for nitrites. All these values are normal for the lettuce cultivated under protection.