Comparative studies on the physio-ecological and morphological adaptations of greenhouse tomato grown in aeroponics and nutrient film technique

The differences in root environment and in growth of tomato plants between aeroponics and nutrient film technique (NFT) were investigated in order to clarify the theoretical background of the hydroponics and then establish an ideal system of soilless culture. The tomato cultivar 'Seokwang' was used for this experiment. The characteristics of the plants in the two different systems were compared under varying temperature, spraying intervals of the nutrients solution and substrata used. Temperature fluctuation in the root environment was greater in the aeroponics than in the NFT, especially when the solution temperature was low. Under the same solution temperature of 25deg C, the plant growth expressed by plant height, stem diameter, leaf number, leaf area, leaf length and the total root length was almost double in the aeroponics than in the NFT, but this difference became less significant as the solution temperature decreased. Plant growth was better in the plots sprayed more frequently. However, the root number/root length ratio became larger as the spraying intervals got longer. The unit shoot rate (USR) did not differ in the two systems and the shoot dry weight partitioned to the leaves was silmilar in the two systems, while that to the stems was higher in the NFT and that to the roots was higher in the aeroponics. The specific leaf area, which negatively correlated with the unit photosynthetic rate of the leaf area, was significantly higher in the NFT than in the aeroponics. The leaf area index was 0.97, 0.88 and 0.51 in the aeroponics sprayed at the intervals of 5 min, 10 min and 20 min, respectively, while it was 0.62 in the NFT. The top/root ratio which was generally higher in the NFT than in the aeroponics during the early stage of seedling growth became similar in the two systems around the beginning of reproductive growth. The days to the first and last flowering were earlier in the aeroponics than in the NFT by 3 days and the number of flowers per plant was more in the aeroponics