Response of Seedlings of Pinus Contorta and Picea Sitchensis to Oxygen Concentration in Culture Solution

SUMMARY Seedlings of Pinus contorta and Picea sitchensis were grown in culture solutions flushed with gas mixtures containing 0–21% oxygen. Pinus contorta was more tolerant of an oxygen‐deficient root environment than Picea sitchensis. When the oxygen tension was lower than in solutions flushed with air, the growth of both species was impaired. Growth of Pinus contorta was severely restricted below 5% O 2 but some growth was measurable even in a non‐aerated solution; growth of Picea sitchensis was severely restricted below 10% O 2 and no root growth was discernible at 3% O 2 or less. Over the 12‐week periods of the experiments shoot extension occurred in all treatments, but was not so clearly correlated with the oxygen concentration around the roots as was root growth.