Nitrate and Nitrite Contents of Sweet Corn Kernels as Influenced by Genotype and Levels of Nitrogen Fertilization

摘要

In sweet corn it is quite expectable that, in poor postharvest condition of ear storage, a smaller or a larger part of the kernel nitrates be converted to nitrites. The consumption of 3-4 freshly boiled ears/day adds up to an ADI of NO2ˉ-N which should be seriously taken into consideration. Five sweet corn hybrids were tested in field trials on four levels of mineral N fertilization (0 kg N/ha; 50 kg N/ha; 100 kg N/ha; 150 kg N/ha) applied to soil as NH4NO3 on a general organic fertilization of 30 t/ha manure applied once in three years. The trials were organized in three locations with obvious different soil and climatic conditions and in two years. At technical maturity, ten ears were harvested at random from each experimental plot and kernel samples of 20 g of each variant were taken on the same day of harvest and analyzed for nitrates and nitrites. Both the cultivar and the level of mineral N fertilization have significantly influenced the nitrate content of kernels. The average value of nitrate (34.41 mg/kg product) and nitrite (1.18 mg/kg product) contents are not very high and are far from being alarming as compared to AID values recommended by the UE Scientific Committee for Food in 2007 (0 – 3.7 mg/kg b.w. of NO3ˉ-N and 0 – 0.1 mg/kg b.w. of NO2ˉ-N). These limits of nitrite content in sweet corn kernels are, nevertheless, alarming since they were found following a rather proper handling and storage of harvested ears and kernel samples.