Experiments on the Relation between Water Absorption and Mineral Uptake by Plant Roots

Maize plants in water cultures were submitted to conditions of high transpiration in the sun and low transpiration in the dark. Transpiration rates were determined together with those of ammonium, potassium, nitrate and phosphate absorption from solutions at pH 6 and 20° centigrade. No significant influence of transpiration on ion absorption was found. These results seem to be at variance with those obtained by Hylmo with peas and by Brouwer with broad beans. However, the ion concentrations used were considerably lower than those used by Hylmo and Brouwer. Moreover, the possibility is discussed that the concentration- and transpiration-dependent component of the ion absorption might be great in pea and broad bean and small in maize. The seeming contradiction would then be reduced to a quantitative difference. The authors are indebted to Mrs E. H. Gloor for her kind help in the correction of the manuscript.