Abstract
Tomato seedlings were grown in a Wet-sheet culture (WSC), where roots developed in the wet atomosphere, or in a Deep flow technique (DFT), where roots were submerged in the solution. They were grown in growth chambers kept at a constant 15, 25, and 35°C. The adaptability of the root systems in the WSC and DFT to high or low temperature was evaluated by comparing the root activity and structure of the systems. Dissolved oxygen in the nutrient solution of DFT was above that normally required for the plants. At all temperatures, tomato plants in WSC grew larger than did those in DFT. The bleeding rate of xylem sap on cut stem was higher in WSC than in DFT at 15°C and 35°C, the root respiration rate per dry weight was higher in DFT than in WSC at all temperatures. The root systems in WSC had more first order laterals and higher projected areas than had in DFT at 15°C and 35°C ; root growth in both systems were similar at 25°C. The fractal dimensions of root systems, known as an index for describing root system morphology, were higher in WSC than in DFT at 15°C. These results indicate that roots in the wet atomosphere would adapt more readily to high or low temperatures than did those in the solution.
