Variation of nitrate content among randomly selected taro (Colocasia esculenta (L.) Schott) genotypes and the distribution of nitrate within a corm

Taro (Colocasia esculenta) is an important staple crop distributed throughout many tropical and subtropical regions. Very little information is available about the nitrate content and its distribution within taro corms. The aim of this study, based on ion chromatography, was to analyze the concentration and distribution of nitrate within four crucial parts (upper, central, marginal, basal) of taro corms of 8 representative cultivars. The results revealed that the levels of nitrate in taro corms were variable depending on the cultivar and corm parts. The highest levels were determined in the upper part of the corm which is used for the multiplication and establishment of a new crop. Therefore, the size of this part is closely associated with the quality of the planting material. As there are no roots, the initial growth of the new taro plant depends entirely on the nutrients accumulated in the upper part of the corm. During the growth season, this part of the corm gradually becomes the lower (basal) part containing the oldest and the least biochemically active tissue, which has the lowest concentration of nitrate ions. The nitrate content in the central part, which is the most important for human nutrition, was relatively low and varied between 29 and 313 mg/kg fresh weight. (Resume d'auteur)