[Incidence of the combination nitrogen-potassium on the vegetative and reproductive development of broccoli (Brassica oleracea var. italica) [cv. Packman]]

The objectives of this research were to determine the effects of nitrogen and potassium fertilization, N-K combination, NxK interaction, and partial application of the nitrogen dose upon the vegetative and reproductive performance of broccoli cv. Packman, as well as, quality of the heads for processing. Nitrogen was applied in 0 and 240 kg/ha, and potassium in 0 and 120 kg/ha. Potassium was incorporated in the ridge at planting together with the base fertilization, which consisted in phosphorus 60 kg/ha and Boronato de Calcita 30 kg/ha. Nitrogen was applied in three different ways: a) one partiality (240 kg NO3/ha) at planting; b) three partialities (80 kg NO3/ha each time) at planting, 15 and 40 days after transplanting; c) five partialities (48 kg NO3/ha each time) at planting, 15, 30, 40 and 50 days after transplanting. The applications of nitrogen after transplanting were done in the irrigation furrow. The data analysis showed a significant effect (p-0.01) of nitrogen application upon the vegetative and reproductive development patterns of broccoli. Nitrogen increased the number and width of leaves, canopy diameter, it decreased the number of days to heading and harvest, increased the yield of principal and lateral heads, and the marketable yield. Nitrogen applied in three partialities increased more the yield of principal and lateral heads, and the marketable yield than other treatments. Potassium application often had no significant effect upon the evaluated parameters. However, it increased the number of days to heading and harvest (p-0.05), and the quality of heads, compaction and color were enhanced, The NxK interaction had always no significant effects (p0.05) in all evaluations carried out. However, the lateral heads and total yield increased for this interaction. The best marketable yield, 18.15 ton/ha, was obtained with three partialities in the nitrogen application and the addition of potassium