Influence of different doses of nitrogen on the yield and nitrate content of lettuce crops

The effect of different nitrogen doses on the nitrate concentration in plan t and yield of an iceberg lettuce crop has been studied. Nitrogen doses of 25, 50, 100, 150 and 200 kg/ha were applied in fertigation. The yield of th e cultivation increased with the dose of nitrogen applied until 100 kg/ha, with 53.4 t/ha of total production of fresh matter and 33.1 t/ha of commerc ial production. with doses of 150 and 200 kg/ha he production of biomass as well as the crop indices were reduced. The external leaves showed the high est nitrate concentration, being significantly lower in the internal ones. The con centrations of N-NO3- at harvest ranged from 1639 to 4494 ppm in ex ternal leaves and from 651 to 1508 ppm in the internals for the different t reatments.