Field experiments were conducted in 2011 on the very light soil in Kruszyn Krajeński near Bydgoszcz. Responses of the three romaine lettuce cultivars grown in spring and autumn to nitrogen fertigation by drip system were compared. Experiments were established as two-factorial trials, four times replicated. The experimental factors were: nitrogen dose of fertigation (25 kg N•ha-1, 50 kg N•ha-1), cultivars (‘Barracuda', ‘Chiquina', ‘Romora'). Fertigation was conducted with the usage of proportional mixing dispenser. Higher marketable yield of romaine lettuce cultivars was noted in spring cultivation. Increased nitrogen dose (from 25 kg N•ha-1 to 50 kg N•ha-1) significantly increased marketable yield of lettuce. From among the tested cultivars, ‘Romora' was characterized by the higher yield in spring cultivation whereas ‘Barracuda' - in autumn. ‘Chiquina' was characterized by the lowest yield. The higher weight of a single lettuce head was noted in spring cultivation. The higher nitrogen dose significantly increased the single lettuce head. The highest single lettuce head was noted in case of ‘Barracuda'. On average for cultivars tested, the higher nitrogen dose caused the decrease of dry matter content in leaves of lettuce grown in spring time, and in case of autumn cultivation this tendency was opposite - the higher nitrogen dose increased the DM content. Lettuce leaves in spring cultivation were characterized by the higher nitrate content as compared to those from the autumn cultivation. The higher nitrogen dose increased the nitrate content in leaves of lettuce. ‘Romora' was characterized by the lowest tendency to accumulation of nitrates in leaves.
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