The purpose of this study was to establish a deep - flow hydroponic culture system to reduce the degree of bitterness in cucumbers (Cucumis sativus L. 'Kema') which consumers do not favor. The effect of the amount of nitrogen application and the ratio of nitrate and ammonia nitrogen on the degree of bitterness and yield of 'Kema' cucumbers grown in hydroponics was analyzed. Commercially available 90% nitrate nitrogen and 10% ammonia nitrogen fertilizers were used for this study. In conventional cultivation, cucumbers were cultivated with 1/2 units of standard (Ohtsuka-A) nutrient solution. The 'Kema' cucumbers cultivated with 2/3 units of standard nutrient solution were more bitter in taste than the ones cultivated with 1/3 units of standard nutrient solution. 'Kema' cucumbers cultivated with less nitrate nitrogen were less bitter in taste than the ones cultivated conventionally. Moreover 'Kema' cucumbers cultivated with less nitrate and more ammonia nitrogen showed more yield than the ones cultivated conventionally. These findings suggest that the bitterness of 'Kema' cucumbers is related to the amount of nitrate nitrogen; additionally, hydroponic cultivation utilizing less nitrate and more ammonia nitrogen can help maintain the yield.
