Single-head broccoli response to nitrogen application

Resumen

Information regarding nitrogenous fertilization in broccoli for Santa Catarina is still scarce. Therefore, this study aimed at analyzing the nitrogen effect upon the levels of chlorophyll (a, b and total), carote­noids and nitrogen (N) forms in leaves, and upon the yield of inflorescence, stem and leaves of single-head broccoli. The experiment was conducted in September, 2011, in Florianópolis (SC), with seed­lings of single-head broccoli (BRO 68 – Syngenta), in completely randomized blocks, with five treat­ments (0, 75, 150, 200 and 250 kg ha^-1 of N, in the form of urea) and three replications. In the bloom­ing, the fourth leaf from the ground was harvested from each broccoli for the following analyses in trip­licate: chlorophyll levels (a, b and total), carotenoids and N forms (NH₄⁺, NO₃^- and mineral N). At the end of the cycle, the yield of inflorescence, body (leaves + stem) and total were estimate. The levels of N lead to increased levels of chlorophyll a, b and total, as well as the N forms in leaves and the yield of inflorescence, leaves, and stem of single-head broccoli. The increased N doses promoted incre­ment of carotenoid levels on leaves until 170 kg ha^-1 of N, having a decrease for superior doses. The N forms in the plant had been incremented with increasing of N doses supply, reflecting in increased yield of broccoli. The N application in the soil stimulated the synthesis of chlorophylls and carotenoids on leaves, promoting better nutritional quality.