The aim of this study was to evaluate the response of Chinese cabbage (hybrid Deneko) to source and rate of N topdressing application. The experimental design was a randomized complete block, consisting of nine treatments (4x2+1 factorial design), with five replications, that is, four rates of N (54, 108, 162 and 216 kgha-1); two sources of N (urea and ammonium sulphate); and a control (without N topdressing). The experiment was conducted from July to October, 2013. Forty days after transplanting, SPAD index (relative chlorophyll density) was evaluated. After harvesting, fresh matter; leaf number; head diameter and head height were evaluated. It was observed that sources of N did not influence any evaluated traits. For the SPAD index, head height and head diameter linearly increased by improving the rate of N, with values which range from 27.0 to 41.1 SPAD units; 25.9 to 29.3 cm; and 8.9 to 13.4 cm, respectively. The effect of N was quadratic for head fresh matter, with maximum value estimated at1217 g for162 kg N ha-1.
Key words: Brassica pekinensis, urea, ammonium sulphate.
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