ارزیابی تجمع نیترات و نیتریت در سبزی‌های تولیدشده در مناطق مختلف اهواز

سبزی‌ها نقش مهمی در سلامتی جامعه دارند. یکی از مشکلات موجود در سبزی‌ها مقدار بالای نیترات آن‌ها در فصل سرد است.جهت شناخت مقدار نیترات و نیتریت سبزی‌های تولیدی در اهواز آزمایشیدر قالب طرح کرت‌های دوبار خردشدهبه شکل کاملاً تصادفی در گروه علوم باغبانی دانشکده کشاورزی دانشگاه شهید چمران اهواز انجام شد. دراین طرح تاریخ برداشت (اول (16 بهمن 1394، دوم (14 اسفند 1394) و سوم (19 فروردین 1395)) بود. در این آزمایشتاریخ برداشت به‌عنوان فاکتور اصلی و 9 گونه سبزی(گشنیز، جعفری، نعناع، شنبلیله، برگ چغندر، اسفناج، تره، شوید و شاهی)به‌عنوان فاکتور فرعی و سه منطقه تولید در اهواز به‌عنوان فاکتور فرعی فرعی تعیین و از هر منطقه، سه مزرعه انتخاب شد. اطلاعات به‌دست آمده با کمک نرم‌افزار sas مورد تجزیه قرار گرفت. نتایج آزمایش نشان داد که مقدار نیترات و نیتریت سبزی‌های تولیدی در مناطق مختلف اهواز با توجه به منطقه، تاریخ برداشت و نوع سبزی متفاوت بود. بیش‌ترین میزان نیترات در فصل اول، در منطقه جنوب اهواز، و در سبزی جعفری و کم‌ترین میزان نیترات در فصل سوم در منطقه شمال اهواز و در سبزی شاهی وجود داشت. همچنین بیش‌ترین میزان نیتریت در تیمار فصل اول، منطقه غرب اهواز و در سبزی نعناع؛ و کم‌ترین آن در فصل دوم، در منطقه شمال اهواز؛ و در سبزی چغندر برگی مشاهده شد. مقدار نیترات و نیتریت گونه‌های مورد بررسی در هر سه منطقهٔ اهواز طی فصول سرد حاوی مقدار بسیار کم‌تر از حدود استاندارد کشورهای اروپایی بودند. بنابراین می‌توان گفت کیفیت سبزی‌های تولیدشده در اهواز از نظر میزان نیترات و نیتریت از کیفیت خوبی برخودار است.

Evaluation of the Accumulation of Nitrate and Nitrite in Vegetables Grown in Different Regions of Ahvaz

Abstract   Background and Objectives Khuzestan Province is one of the most important areas that provide vegetables throughout winter and spring in Iran. The vegetables are mainly picked up in the afternoon, so it cannot be supplied to the market. In this time of the day, the minimum amount of nitrate is accumulated in leafy vegetables, with a gradual increase throughout the night. On the other hand, its highest level is in the early hours in the morning. The purpose of this study is to evaluate nitrate and nitrite accumulation in vegetables produced in different areas of Ahwaz during winter and spring.   Materials and Methods This experiment was conducted in a randomized complete block design arranged in a splitsplitplot design with three replications in the Department of Horticulture, College of Agriculture, Shahid Chamran University of Ahvaz. In the treatments viz. first to third harvest dates (1): February 6, 2016, (2):March 4, 2016 and (3): April 7, 2016 respectively were the main factors and nine vegetable species (including coriander, parsley, mint, fenugreek, chard, spinach, leeks, dill and watercress) kept in sub plot, three vegetable production areas in Ahvaz were arranged in sub plot in sub plots and three fields were selected in each of these areas. Before and after cultivation, all planting, harvesting and harvesting operations were carried out on the same field in the selected fields. The concentration of nitrate was measured by the method introduced by Cataldo et al. (1975) and the nitrite concentation was measured via the method of AbuDayeh (2009). The data were analyzed using SAS software and the mean comparison was calculated using Duncan’s multiple range tests at a probability level of 5%.   Results Nitrate and nitrite contents of the produced vegetables were different depending on various regions, harvesting time and vegetable species. The highest nitrate content was observed in parsley fromthe first harvest in the southern region of Ahwaz (4.4 mg/kg1 dry matter) and the lowest amount of nitrate was recorded in watercress from the third harvest in the northern region of Ahvaz (1.4 mg/kg1 dry matter). Also, the highest nitrite content was observed at the first harvest in the westhern region of Ahwaz in mint and the lowest amount of nitrate was recorded in the second harvest in the northern region of Ahvaz in chard. In winter, the environmental conditions in Ahwaz are suitable for the growth and development of leafy vegetables (Boroujerdnia et al., 2007); however, soil conditions provide manganese uptake by plants. Moreover, high light intensity is another factor which can decrease nitrate in leafy vegetables. The number of cloudy days in Ahwaz is very low; therefore, the number of sunny days with high radiation intensity is high in winter. This phenomenon greatly reduces the content of nitrate in leafy vegetables.   Discussion The amounts of nitrate and nitrite content in various species of vegetables produced in three regions of Ahvaz during the cold season were much lower than the standard figures. Therefore, we can conclude that the quality of vegetables produced in Ahvaz is very high in terms of nitrite and nitrate contents.