ABSTRACT
In the management of single head broccoli nitrogen fertilization, there is no study indicating the critical level and adequate range of N content and SPAD index in the leaves to evaluate the nitrogen nutritional status. This work was carried out in two consecutive years with control without N and three rates of N (150; 300 and 450 kg ha-1). The treatments were arranged in the experimental design of random blocks, with four replications. All productive characteristics were significantly influenced by N rates. The fresh inflorescence mass reached a maximum value of 822 g with 308 kg ha-1 N. The critical levels were 61.1 g kg-1 for total N foliar content and 71.31 ud SPAD at 40 DAT. The SPAD index presented high correlations with the total N content in the leaves (r = 0.93; p<0.034) and with the maximum fresh mass of the inflorescence (r = 0.99; p<0.001). The ranges of N content (low ≤52.5; medium 52.6 to 57.4; sufficient 57.5 to 61.1 and high >61.1 g kg-1) and SPAD index (low ≤68.48; medium 68.49 to 70.47; sufficient 70.48 to 71.31 and high >71.31 ud SPAD) are proposed for assessing the N nutritional status of single head broccoli.
Keywords:
Brassica oleracea var. italica; nutritional diagnosis; nitrogen fertilization
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