Selenium Absorption by Excised Astragalus Roots

Selenium absorption by excised Astragalus roots.

Absorption of selenate and selenite by excised roots of Astragalus Crotalariae, a selenium accumulator, and of A. lentiginosus, a non-accumulator, was favored by CaCl(2) and a pH of 4.0. The uptake of selenate and possibly selenite, is metabolically linked. Roots of a number of Astragalus species were examined, and in all cases selenate entered the roots much faster than selenite. In these shor...

Manganese absorption by excised barley roots.

Short-term absorption studies with 5-day-old excised barley roots revealed that the basic aspects of Mn absorption were similar to those of other metabolically absorbed cations. Following an initial non-metabolic equilibration with the root, Mn was absorbed for several hours at a slower steady-state rate comparable to that of other inorganic cations. Complete or nearly complete inhibition of th...

Respiration and Salt Absorption by Excised Barley Roots.

Absorption of Magnesium and Chloride by Excised Corn Roots

Absorption characteristics of Mg2+ and Clwere investigated with 5-day-old excised corn (Zea inays) roots. Uptake from both 0.5 and 10 milliequivalents per liter MgCl2 solutions occurred at steady state rates for the first 6 hours. Inhibition by dinitrophenol and low temperatures established that absorption during this period was metabolically mediated in the absence and presence of Ca2+. Absorp...

Effects of temperature on orthophosphate absorption by excised corn roots.

The uptake of orthophosphate ((32)P) by excised corn roots, Zea mays L. was studied using roots grown on 0.2 mm CaSO(4). Nine concentrations of KH(2)PO(4) from 1 to 256 mum were used at temperatures of 20 degrees , 30 degrees , and 40 degrees . Enzyme kinetic analysis was applied to the data obtained. Two apparent mechanisms (sites) of phosphate uptake were observed, 1 dominating at high P conc...