Similarly, lower increase in lettuce nitrate concentration has been reported, when using organic fertilization, high in nitrogen levels, compared to the inorganic fertilization 38, 39. The highest nitrate values were observed during the winter crop, characterized by short photoperiod and sunshine duration, regardless treatment and cultivar in agreement with other similar reports 15, 39. The accumulation of nitrate in all treatments was far below the maximum limits set by the E. C. 563/2002 regulation for lettuce fresh produce. The reduced concentration of nitrate observed in the cultivar Gentillina in both crop seasons confirms that the selection of cultivars with genetically controlled nitrate accumulation in the leaves is one way to deal the problem even when using alternative ways of fertilization such as vermicompost 15.