Calcium Uptake and Transport by Wheat Seedlings as Affected by Aluminum

Abstract

AbstractUptake and distribution of Ca was studied with excised roots and intact seedlings of wheat. Patterns characteristic of inorganic ion uptake by roots were obtained, namely a rapid initial adsorption phase followed by a linear rate of accumulation. The former was relatively large compared to the latter. It also was reduced to a greater extent by increasing acidity from pH 6 to pH 4. The Ca accumulation phase was reduced by modest restrictions in aerobic metabolism. Treatments resulting in severe reductions in metabolism produced a loss of internal inorganic cations and an increase in influx of external Ca indicating serious objections to the sole use of isotopic procedures for ion uptake studies under such extreme conditions.Aluminum treatments reduced both the adsorption and accumulation phases of Ca uptake. The reduction in the accumulation phase could not be overcome by supplying additional Ca. Increasing the Al concentration from 10‐4N to 10‐3N at constant Ca did not alter the extent of inhibition, suggesting that a portion of the Ca accumulation mechanism was inactivated completely by Al at 10‐4N or less.Transport of Ca to shoots of intact seedlings also was restricted by Al although appreciable transport still occurred when root uptake was inhibited completely.