Keywords: Allium cepa L., foliar urea, bulb production and quality, foliar penetration routes.
Foliar fertilization in onion has had inconsistent results, which prevent adequate management nutrition for this crop. Therefore, the present study had the objective of quantifying the effect of foliar fertilization in bulb yield and quality, through the evaluation of the activity of physiological processes, fertilizer penetration routes, and canopy nutrient concentration. To accomplish this objective, a field experiment was established in 2001, were five foliar fertilizers and a control were applied in a completely randomized experimental design with six replications. There was no increase in bulb yield and quality. There were also no significant differences in the expression of physiological variables such as CO2 diffusion, CO2 assimilation, stomatal conductance, stomatal resistance, transpiration rate, N, P, K, Ca, Mg, B, Cu, Fe, Mn and Zn foliar tissue concentration. When studying the penetration of foliar urea plus calcofluor colorant, urea entered through the stomata and, to a lower degree, through the cuticle of plants at 75 and 113 days after transplant.