Nitrogen fertilization for noble garlic production in high altitude regions of the Brazilian semiarid region

Rio Grande do Norte State in Brazil has microregions with altitudes where the edaphoclimatic conditions are fa­vorable to the cultivation of garlic, including vernalized noble garlic. An example is the municipality of Martins, where vegetable cropping is not a traditional practice. Since it is a region with potential for cultivation of noble garlic, comprising soil and climate conditions that are distinct from traditional production regions in Brazil, the use of nitrogen fertilization becomes an alternative to increase crop yield. This fact can stimulate the semiarid pro­ducer to invest in the crop, once it guarantees greater economic return. Thus, aiming to evaluate the production of vernalized noble garlic as a function of nitrogen doses applied in top dressing, an experiment was developed from May to August 2014, using a complete randomized complete block design with five replicates. The treatments consisted of the cover application of increasing doses of N (0, 40, 80, 120, and 160 kg ha -1 ). The following were evaluated: plant height; number of leaves; average bulb weight; total, commercial, and noncommercial bulb yield; bulb and bulblet classification; and number of bulblets per bulb. The dose of 90 kg ha -1 nitrogen, applied in top dressing, provided the highest averages of plant height, number of leaves, average bulb weight, and total bulb yield. The dose of maximum economic efficiency was 91 kg ha -1 , which promoted greater commercial bulb yield. The number of bulblets per bulb and bulblet classification were not influenced by nitrogen doses applied in top dressing.