Nitrate and Nitrite Accumulation in Iranian Spinach (Spinacia oleracea L.) Landraces

There is considerable concern that use of high nitrate and nitrite containing vegetables such as spinach could cause diseases. This research was conducted with the objective of examining the nitrate (NO3-) and nitrite (NO2-) accumulation in the aerial parts (leaves and petiols) of 44 Iranian spinach (Spinaciaoleracea L.) land races that were obtained from field grown plants. Statistical analysis was conducted by using standard procedures for a randomized complete block design (44 treatments and 3 replications). Nitrate and nitrite contents in the aerial part of samples were determined using UV-Visible Spectrophotometric. Results indicated that the nitrate content in the aerial part of Iranian spinach land races ranged from 3526.5 to 8806.5 μg.g-1 dry weight. The ‘Saleh Abad’ (from ‘Qom’), ‘Rehnan’ (from ‘Isfahan’), ‘Sar Asyab-1’ (from ‘Kerman’), ‘Sirjan’ (from ‘Kerman’), ‘Qazvin’, ‘Zanjan-2’ and ‘Khoram Abad’ were found to contain maximum accumulation on nitrate (8806.5 to 7092 μg.g-1 dry weight). Nitrate concentration in leaves of ‘Sar Asyab-2’ (from ‘Kerman’) and ‘Mahan’ (from ‘Kerman’) was significantly low (3526.5 to 3594 μg.g-1 dry weight, respectively). The nitrite contents were lower (between 73.8 to 188.7 μg.g-1 dry weight(than nitrate content in all Iranian spinach land races. The different spinach land races show the significant effect on the nitrite contents in this study. Spinach land races which were collected from ‘Khoram Abad’, ‘Varamin-1’, ‘Mahan’, ‘Bojnord-1’, ‘Qom’, ‘Sari-2’and ‘Ravar’ (from ‘Kerman’) showed the lowest average of nitrate contents among other land races, with a range of 73.8 to 89.51 μg.g-1 dry weight. While the highest nitrite content in spinach land races were with a range of 188.7 to 163.1 μg.g-1 for ‘Sar Asyab-1’ (from ‘Kerman’), ‘Yazd’, ‘Hamedan’, ‘Karaj’ and ‘Bor An’(from ‘Isfahan’). Results indicated that the mean of nitrate or nitrite content in these land races were statistically significant.The variation of nitrate content in the leaves of Iranian spinach land races also make them ideal for breeding program.