The influence of training methods on the yields of cucumber (Cucumis sativus) was investigated in the aspects of root characteristics. The experiment was conducted in the new Nutrient Film Technique hydroponics system specially developed for cucumber production (Mitsubishi Chemical Aqua Solutions, Co., Ltd., Tokyo, Japan).The lowering training (LT) and the pinching training (PT) were used to manage the cucumber plant’s canopy during the growth cycle. At the end of the experiment, the xylem sap bleeding rate, the root biomass, the remaining aerial biomass and the main stem diameter were measured. In addition, individual fresh and dry weights of matured leaves at the lower, middle and upper parts of the plant’s canopy were measured during the growth period. The recorded fruits yield was used for a correlation test with the xylem sap bleeding rate. The results indicated that the sap bleeding rate, root dry weight and root dry and fresh weights ratio were significantly higher in LT treatment. Similarly, the remaining aerial biomass fresh weight was significantly greater in the same treatment. On the other hand, individual leaf fresh and dry weights and the main stem diameter were significantly greater in the PT treatment, at the middle and upper parts of the plant’s canopy. These results were explained by the fact that in the PT treatment, more carbohydrates produced by plants were apparently used to re-establish the pinched shoots at the expense of root production. Moreover, after pinching the lateral shoots, biomass production was improved due to the penetration of sunlight in the plant’s canopy. Considering the relationships between root traits and plant productivity, the LT method is suitable for a long-term cultivation due to its faster sap bleeding rate, which is necessary to stimulate root physiological activity and promote plant biomass production.