Nitrate accumulation pattern in Brassica under nitrogen treatments

Besides being a rich food source of vital nutrients, many green leafy vegetables are nitrate accumulators. This study is focused on genotypic variability in nitrate accumulation and the diurnal rhythm of nitrate content in different Brassica genotypes. Out of 10 genotypes grown under the same environmental conditions, a high-nitrate-accumulating (HNA) and a low-nitrate-accumulating (LNA) genotypes (designated as G5 and G8, respectively) were selected to determine the effect of various N fertilization rates on the nitrate accumulation pattern in different edible parts of these genotypes. Petiole accumulated the maximum nitrate and should therefore be discarded in order to avoid excess nitrate intake by humans. A low dose of nitrogen fertilizers is advised for HNA genotypes at the time of sowing, because nitrate accumulation attains unsafe levels at higher doses. Nitrate content increased with advancing age of the plant and therefore harvesting should preferably be done at an early age. A separate experiment was conducted to determine the role of light intensity in regulating the nitrate level in the genotypes studied. The plants kept in shade accumulated comparatively more nitrate than those kept in sunlight, showing an inverse relationship between light intensity and nitrate accumulation. The results indicate that LNA genotypes should be preferred for human consumption.