| Abstract: | The absorption and distribution of strontium in barley plantshas been studied, in water culture, both in the presence andabsence of calcium. Tracer methods have been employed. When no other bivalent ions were present in the external solutionthe absorption of strontium was proportional to the concentrationover a wide concentration range (10–6 to 10–1 m.equiv./l.).In the presence of calcium, however, absorption was reducedand appeared to be dependent on the total concentration of calciumplus strontium rather than on that of 8trontlum alone. The translocationof stron tium from the root to the shoot increased as the externalconcentration of both ions was raised. In plants of low initialcalcium status the rate of translocation of strontium was markedlyreduced, apparently because of its retention at or near theroot surface. Autoradiographs of plants treated with labelled strontium for24 hours at different stages of growth and grown subsequentlyfor varying periods of time in unlabelled nutrient solutionsshowed that very little redistribution of strontium occurredwithin the plant. Leaves which developed after treatment inthe labelled solutions contained little or no strontium evenwhen the concentration in the older leaves was very high. Strontiumwas initially retained in the nodes of the stems, but the greatestaccumulation was later found to be in the leaves which had beengrowing most actively at the time of absorption. |
