Nitrate Content on Summer Lettuce Production Using Fish Culture Water

The aim of this study was to investigate the nitrate concentration on lettuce (Lactuca sativa cv. Px06516006) grown in fish culture water. This study was carried out in Queretaro State, Mexico. Lettuce cultivars were grown in a floating system inside a plastic greenhouse. The cultivation of lettuce was divided into 10 beds; four beds were used as a control group, with a standard nutrient solution and the other six beds were used as treatment group, fish culture water with the addition of missing nutrients. A density of 30 plants m-2 was used. Two trial periods were tested in the summer of 2008, 29 days from April 11 to May 9 for the first experiment and 37 days from May 22 to June 27 for the second experiment. The system was assessed on basis of leaves nitrate content, total fresh weight and total dry weight. In both trials the final nitrate content of leaves was less than 2400 mg kg-1. No significant differences (p<0.05) were found for fresh and dry weights among treatments. Based on these results it is shown that fish culture water is suitable for low nitrate content lettuce production with no detriment to plant quality neither yields during summer.