Overview of Nitrate Concentration in Some Vegetables Produced in Zanjan Province

Nitrate is an anion that may be transformed to nitrite, which reacts with amines and amides to produce N-nitroze compounds. These compounds increase the risk of gastric cancer. The purpose of this study was to determine the concentration of nitrate in some vegetables in Zanjan province. This descriptive cross-sectional study was conducted randomly in two harvest years (2014-15) on 614 samples of 23 kinds of different cultivated vegetables including Allium cepa L,  vulgaris subsp, Petroselinum crispum, Lepidium sativum, Spinacia  oleracea, Anethum graveolens, Apium graveolens, Coriandrum sativum, Trigonella foenum-graecum, Ocimum basilicum, Mentha piperata, Summer savoury, Raphanus sativus (leaves), watermelon, melon, tomato, cucumber, potato, onion, garlic, radish, green peas, and broad bean. Concentration of nitrate in vegetables and irrigation water samples were determined by spectrophotometric method and data was analyzed using SPSS and SAS software. The results showed significant (p≤0. 001) differences between the mean concentration of nitrate in leafy vegetables and other vegetables groups (tubers, cucurbits and seed vegetables). Among the leafy vegetables studied, the highest average nitrate concentration was found in Lepidium sativum, Spinacia oleracea, and Anethum graveolens, equal to 689. 3, 368, and 317. 5 mg. kg-1 fresh weight, respectively. In general, the average nitrate concentration in all samples in the two study years was less than the National Sandards of Iran (2013).