Centesimal composition, contents of Vitamin C and nitrate in six cultivars of produced lettuce in four hydroponics solutions

Abstract

The nutritive requirements of the human body has been object of intense investigations in the last years. There is also an interest on chemical characterization of vegetables with economic and nutritional potentiallity. Based on the fact that nitrate in excess is harmful to the human health, levels of nitrate were analysed in six cultivars of lettuce, three of the flat type: Regina, Dawn and Lívia and three of the curly type: Brisa, Mimosa and Veronica, grown in four nutrient solutions (Ueda, Furlani, Castellane & Araújo e Bernardes). The experiment was carried out at Crop Production Department, Federal University of Santa MarialRS, Brazil. Plants were collected C{njuly 13th, 1998,39 days after sown. The statistical analysis showed interaction between levels of nitrate, Vitamin C, fiber and mineral residue. The Ueda increased dry weight, caloric value, levels of lipids and fibers, depreciating the quality of the final product, in spite of presenting very low nitrate level. Plants cultivated in Castellane & Araujo and Furlani or Bernardes, solution presented levels of nitrate below the critica for every cultivar, keeping the nutritional quality similar to the lettuce grown in the soil for the levels of protein, lipids, fiber and ashes, presenting smaller caloric value, which is of fundamental importance for people diet and a high content of Vitamin C. The hydroponic lettuce can be considered a desireble vegetable for a human nutrition with low caloric value, easy to clean and with high durability.