Tissue distribution of glycinebetaine,proline and inorganic ions in barley at different times during the plant growth cycle.

The study of tissue distribution of glycinebetaine in barley grown hypoponically revealed that, during the vegetative growth period, young actively growing leaves accumulated higher levels than the mature lower leaves. Proline showed a complex pattern of leaf distribution. While K⁺ and Cl^‐ were uniformly distributed, the former being at a much higher concentration, levels of Na⁺ Ca²⁺ and Mg²⁺ were generally higher in the older leaves than the younger leaves. As the plants matured their leaves contained higher levels of divalent cations. The ear contents of glycinebetaine, proline, Ca²⁺ and Mg²⁺ increased with the ear maturity. The relative contribution of cations to the tissue osmotic pressure is discussed.