The Effect of a Low Oxygen Content of the Medium on the Roots of Barley Seedlings

Barley seedlings were cultivated on aerated nutrient solutions (air-plants), and on nutrient solutions through which nitrogen gas was passed (nitrogenplants). Roots of nitrogen-plants died when the shoots were deprived of air. Roots of intact nitrogen-plants absorbed, from a solution which contained oxygen, less of this gas than roots of air-plants. In air, the respiration per mg dry-weight of roots of nitrogen-plants, was considerably higher than the respiration of roots of air-plants. It is concluded that in a solution deficient in oxygen, the roots of nitrogen-plants receive this gas from the shoots by diffusion along the intercellular spaces. In short-term experiments, the uptake of chloride by nitrogen-plants, calculated per mg dry-weight from a solution deficient in oxygen, was about equal to the chloride uptake by air-plants from aerated solutions. The uptake of potassium by nitrogen-plants from a solution deficient in oxygen was higher than that by airplants from an aerated solution. When nitrogen-plants were transferred to aerated solutions, the uptake of both chloride and potassium, was much higher than the uptake of these ions by air-plants. The content of soluble sugars of the roots of nitrogen-plants was more than 100 % higher than that of the roots of air-plants; their protein-content was from 4 %-25 % higher.