Abstract
1. Investigations were carried out on the influence of oxygen tension in the soil on the growth and uptake of nutrients of tomatoes, cucumbers, and egg-plants.
2. Tomato plants died when the soil was aerated with mixtures containing 2 percent oxygen. When the pressure of oxygen was low, the peti-oles of tomatoes drooped and numerous adventitious roots were found to grow on the stem up to the middle of it. No significant difference was found in the growth of tomato plants on the soil which was aerated with mixtures containing 10 percent oxygen compared to that of the same on the soil containing 20 percent oxygen.
3. Cucumbers remained alive even on the soil aerated with air which contained very little oxygen. But the growth of the plants were the greatest on the soil with 20 percent oxygen.
4. Egg-plants continued their growth on the soil which contained only a small quantity of oxygen. And no difference was found between the growth of them on the soil with 10 percent of it, and with 20 percent, but the growth of the leaves was found greater on the soil with 10 percent-oxygen than that on the soil with 20 percent of it.
5. Similar tendency of influence of oxygen tension in the soil was observed about the absorption of water as well as the growth of plants.
6. The concentration of nitrogen in the leaves .of these fruit crops grown on the soil aerated with mixtures containing 0 or 2 percent oxygen was less tha.i that of plants aerated with 5, 10, or 20 percent oxygen. But there was observed no difference of concentration of nitrogen in the
leaves among the plants aerated with mixtures containing 5, 10, or 20 percent oxygen.
The concentration of nitrogen in the stems of cucumbers and egg-plants was enhanced by increasing oxygen in the soil, but the contrary tendency was found in the stems of tomatoes.
7. The concentration of phosphate and potassium in the plants was affected remarkably by the aeration of the soil; it became high according to the increase of the oxygen tension in the soil. And the tendency was greater in cucumbers than in others.
8. The amounts of phosphate and potassium absorbed by the plants were intensified according to the increase of the oxygen in the soil atmosphere. And a remarkable decrease of them was found in the plants grown in the mixtures containing oxygen below 5 percent.
The uptake of nitrogen by these fruit crops decreased very much on the soil aerated with mix-tures containing 2 percent oxygen compared to that in the case of 5, 10 or 20 percent oxygen. But there was no significant difference among toma-toes which were grown on the soil aerated with 5, 10, or 20 percent oxygen respectively, neither was there any difference between egg-plants grown on the soil containing 10 and 20 percent oxygen. And some of the plants which were grown on the soil 10 percent oxygen absorbed more nitrogen than those grown on the soil containing 20 percent oxygen.
In the tomatoes, nitrogen absorbed by them at low oxygen pressure was gathered chiefly in the stems.
