Abstract

SANCHEZ, Teresa Margarita et al. Protein and nitrate levels in crisp lettuce and vegetable amaranth produced with amendment and urea. Rev. Chapingo Ser.Hortic [online]. 2012, vol.18, n.2, pp.217-226. ISSN 2007-4034.  https://doi.org/10.5154/r.rchsh.2011.02.027.

In Argentina, lettuce (Lactuca sativa L.) is the most common vegetable used in salads, while amaranth (Amaranthus mantegazzianus Pass.) is characterized by its high production of green matter, with high protein and mineral levels; both species are considered accumulators of nitrate, so in order to avoid health problems for the consumer, the European Commission regulates the levels of nitrate in lettuce. In order to assess the accumulation of nitrates in both species and evaluate the protein levels and dry matter content, a trial was conducted at the Faculty of Agronomy, UNLPam, Santa Rosa, La Pampa, Argentina. On December 28, 2009, crisp lettuce was transplanted and amaranth was sown. Four levels of fertilization were added for both species: 1) Compost base: 10 dm³·m^-2 moderately composted manure, 2) Double Compost: 20 dm³·m^-2 moderately composted manure, 3) Compost base + 30 kg·ha¹ urea and 4) Compost base + 60 kg·ha¹ urea. An experimental design of randomized complete blocks with five replications was employed; significant differences in nitrate levels between species and levels of fertilization were obtained. The values in lettuce were 2.9 % dry basis and 2,634 mg·kg^-1 fresh^-1 and in amaranth 4.1 and 4,764, respectively. In the case of fertilization levels, compost base with 10 dm³m^-2 manure differed from other treatments, for both species studied. Under evaluation conditions, amaranth exceeded the thresholds stipulated by the European Commission. Protein levels showed significant differences between species (20.2 % in lettuce and 24.8 % in amaranth).

Keywords : Lactuca sativa L; Amaranthus mantegazzianus Pass; nitrate; crude protein.