Long-distance transport of alkali metals in maturing wheat

The alkali metals cesium, rubidium, lithium and sodium were introduced toge ther with strontium via flaps into leaf laminas or into the stem of maturin g, intact winter wheat (Triticum aestivum L. cv. Arina) grown in a field. L ong-distance transport of these elements and the influence of the applicati on date and of different application positions were investigated. The phloe m-immobile Sr served as a marker for the distribution of the xylem sap in t he plants. Dry matter accumulation in the grains and the transpiration per shoot were not markedly affected by the treatments as compared to control p lants. The phloem mobility was rather high for Cs and Rb. Li was almost imm obile in the phloem (similarly to Sr). An application into the cut stem xyl em below the second leaf node contributed more to the contents in the grain s than an application into the flag leaf. An earlier feeding date led to a higher accumulation in the grains. The marked losses of the elements applie d during maturation (most pronounced for Li) can be explained by leakage in the rain.