Effect of nitrogen fertilization on yield and color of red garlic (Allium sativum L.) cultivars

The aim of this work was to evaluate the effect of 0, 75, 150, 225, and 300 kg.ha(-1) of nitrogen fertilization on the yield and color of red garlic (Allium sativum) cvs. Fuego, Sureno, Gostoso, INCO 30 and Rubi. Treatments were distributed as split plot design and disposed in random complete blocks with three replicates. The nitrogen rates were assigned to main plots and the cultivars to subplots. The color of bulbs was determined with a reflectometer Minolta CR-400. Cultivars and nitrogen rates had a significant effect (p < 0.0001) on yields; however, the interaction between the nitrogen rates and yields was not significant. Garlic cultivars digressively sorted according to the yields were(t.ha(-1)): Sureno(11.8),Rubi (11.7), Gostoso (10.0), 1 NCO 30 (10.0), and Fuego (9.8). A highly significant interaction between Cultivars and nitrogen rates were obtained for color variables. Considering all nitrogen fertilization treatments, cv. Rubi (Hite*: 33) had the highest purple color and cv. Fuego (Hue*: 52) had the lowest one, resulting in an intermediate level for cultivars INCO 30 (Hite*: 47), Sureno (Hite*: 45), and Gostoso (Hite*: 43). A trend toward higher purple-red color as nitrogen rates increase was obtained for Sureno, Rubi and Gostoso. The color values obtained for each cultivar and extreme rates of nitrogen fertilization (0 and 300 kg.ha(-1)) were (Hite*, L* and Cr*) for Fuego N-0 (57.2, 64.8, 19.5), N-300 (43, 69.7, 17.0), Gostoso: N-0 (50.7, 64.1, 18.4), N-300 (42.8, 63.3,18.2), INCO: 30 N-0 (44.5, 61.1, 19.3), N-300 (47.4, 64.6, 17.6), Rubi: N-0 (42.0, 60.4, 20.3), N-300 (33.2, 60.0, 19.5), Sureno: N-0 (47.7, 61.5, 20.1), N-300 (43.5, 62.8, 18.6).