Nitrogen and potassium fertilization on cabbage biometrics and foliar nutritional levels

Among the most absorbed nutrients by cabbage, nitrogen (N) and potassium (K) are the most extracted; thus, the objective of this study was to evaluate the responses of N and K fertilization on the cabbage biometrics and foliar levels of macro and micronutrients. Four N doses (0, 75, 150, 300 kg ha-1 of N) and four K doses (0, 75, 150, 300 kg ha-1 of K2O). Biometrics of cabbage head (height, circumference and diameter) and productivity were evaluated. The cabbage levels of macro and micronutrients were also evaluated in leaves of plants at the phenological stage of head-formation. Nitrogen fertilization did not significantly affect the variables evaluated mostly due to the great natural fertility of the experimental soil area. This lack of response highlights the importance of constant monitoring of the nutritional status of the productive area to avoid non-necessary N fertilization. The lowest Mg leaf content was observed at 88 kg ha-1 of K2O, after which the Mg leaf content increased. The foliar Zn was reduced in doses after 133 kg ha-1 of K2O. The cabbage head diameter and circumference decreased with the increase of the K2O doses. The cabbage head height increased up to 128 kg ha-1 of K2O. The decreasing sequence of the macro and micronutrient levels in cabbage leaves followed the sequence K>Ca>N>S>Mg>P and Mn>Fe>B>Zn>Cu regardless of the level of the factors applied.