Manganese absorption by excised barley roots.

Influence of calcium and magnesium on manganese absorption.

Mutual effects between Mn, Ca, and Mg were studied during steady-state absorption experiments with excised barley roots. Calcium appeared to enhance the rate of Mn absorption; whereas, Mg had a highly depressive effect. The combination of both Ca and Mg was even more inhibitory to Mn absorption than Mg alone. Manganese had no effect on the usual negligible Ca absorption by this tissue, but effe...

Accumulation of Calcium in Exudate of Individual Barley Roots.

Metabolic absorption of Ca by plant roots has been reported to be extremely slow in comparison to the alk?li cationis ad Mg (A,77 14, 15, 16). In certain root tissues, metabolic absorption of Ca was difficult to detect if it occurred at all (1, 9, 14, 18). Since the intact plants of most species are known to take up a large amount of Ca, these results appeare(l to support the hypothesis of solu...

Respiration and Salt Absorption by Excised Barley Roots.

Calcium inhibition of potassium absorption in corn roots.

Calcium (or magnesium) sulfate or chloride was found to inhibit energy dependent potassium transport in excised corn roots. This Ca(2+) inhibition of K(+) transport was most pronounced during the initial phases of transport. As the absorption periods were lengthened the effect of Ca(2+) gradually changed from an inhibition to a typical promotion (after about 30-45 mins) of K(+) transport. Kinet...

Carbon Dioxide Fixation and Salt Uptake in Particulate Preparations from Barley Roots.

Previous workers (4, 6) have shown that CO2 fixation in excised roots is related to ion absorption since an absorption of excess cations results in an increase in both the CO2 fixation and in the formation of labelled malic acid. The accumulation of cations and anions has been demonstrated in both animal (1, 5, 8) and plant (7) mitochondria, and in view of Robertson's hypothesis that the mitoch...