EM RESPOSTA À ADUBAÇÃO NITROGENADA

GREEN HUE IN VERNALIZED GARLIC LEAVES IN RESPONSE TO NITROGEN FERTILIZATION A field experiment was carried out in order to determine the feasibility of monitoring nitrogen fertilization of vernalized garlic production by means of the correlation between the indirect measurement of the intensity of the green hue of the leaves (SPAD chlorophyll meter) and the plant nutritional condition and bulb yield. A randomized complete block design was used with six doses of nitrogen (0, 20, 40, 80, 160, 320 kg ha -1 ) and five repetitions. Nitrogen rates were side-dressed applied at the 20 th and the 75 th days after emergence. Data were collected for green hue intensity (GHI) and N content of leaves, average weight, total production and bulb classification as per size. Nitrogen concentrations as well as GHI were affected by N rates. Significant correlations were found between GHI and N content of leaves, between bulb production and GHI, and also between output and N contents. The maximum GHI value was attained a N rate of 250 kg ha -1 and the maximum productivity and the maximum average bulb weight were attained at 268 kg ha -1 . Given the proximity of these rates, these results indicate that chlorophyll measurement can be used for the recommendation of nitrogen fertilization of garlic cultures. The best economic return was obtained with a 237 kg ha -1 N rate.