Effect of dissolved O2 levels in a nutrient solution on the growth and mineral nutrition of tomato and cucumber seedlings.

摘要

The root systems of tomato cv. Hausu-Momotaro and cucumber cv. Sharp 1 seedlings were subjected to 4 different dissolved O2 (DO) concentrations in nutrient solution for 8 days under artificial light conditions. DO concentration was kept constant at1, 2, 4 or 8 ppm and solution temperature was controlled at 22 or 30鳦 for tomatoes and at 25 or 33?for cucumbers. Growth of tomato plants at 1 or 2 ppm DO was inferior to that at higher DO values, irrespective of solution temperature. Growth of cucumber plants was slightly retarded at 1 ppm when the solution was held at 25? at 33? growth was significantly inhibited at 1 and 2 ppm DO, similar to tomato. Possible causes of the difference in the tolerance to low DO levels between tomatoes and cucumbersare discussed in relation to morphological changes and iron-induced oxygen radical formation in the roots.