トマト幼植物の生長および養水分吸収に及ぼす培養液流動の影響

抄録

The effects of increased flow rate of nutrient solution on growth and ion uptake by tomato (Lycopersicon esculentum Mill.) seedlings cultivated by deep flow technique (DFT) were investigated: (1) Respiration rates of detached roots with a manometer at various stirring rates, (2) absorption of water and ¹⁵N by seedlings at various stirring rates and (3) the effects of the flow rate of the nutrient solution on the seedling growth. The respiration rate of the roots increased with the stirring rate of the solution. Even though the level of dissolved oxygen (DO) dropped rapidly, it stayed at a constant value. Absorption of water and ¹⁵N also tended to increase with increasing stirring rate, and this increase in absorption was independent of DO. The higher flow rate stimulated growth of tomato plants in DFT in the greenhouse. Changes in the flow rate of the solution may affect plant growth through changes in 2 factors: (1) the level of DO in the solution, and (2) the transfer rate of oxygen and ions close to the root surfaces, where the diffusion process is dominant. These results support the hypothesis that a so-called ‘root boundary-layer’ may exist on the root surface.