Light supply and nitrogen fertilization for the production and quality of butterhead lettuce

To improve yield and quality of greenhouse Butterhead lettuce, two different N fertilization treatments (Treatment 1 - organic (vermicompost) and treatment, 2-mineral (94% Ca(NO3)(2) and 6% NH4 NO3)) and compared with a control (without fertilization). Plants were grown in containers and situated in two different sections of the greenhouse (24hs artificial light supply and no light supply). Lettuce were harvested with commercial size and contents of Vitamin C and of nitrate were measured. Plants grown with artificial light supply presented larger yield and shortened 15 days the time to harvest. Vermicompost treatment had the best yield, 10% larger than mineral treatment and 40% more than control treatment. Light supply lowered nitrate content of each treatment compared to the same treatment without artificial light supply. Mineral treatment without artificial light supply had the larger nitrate content. Vitamin C contents were similar among treatments, although vermicompost had the larger content. Light was a positive factor for production and quality. Vermicompost represented the best option since a greater yield with a lower content of nitrates and good content of vitamin C occurred.