Phosphorus-containing Compounds at Comparable Germination Stages of Caryopses of Avena Species

Abstract

A number of the phosphorus transformations accompanying imbibition and initial germination in caryopses of wild oats (A vena fatua L.) differ in nature and kind from those accompanying seedling development. Even in non-dormant lines of wild oat germination is extended and seedling development uneven. The significance of early phosphorus transformations can be obscured. Procedures to synchronize germination stages were developed by (i) using seeds which had been exposed to room temperature for extended periods of dry storage, (ii) inducing germination of imbibed seeds by dehulling, piercing and/or gibberellin A3 treatments, or (iii) constructing artificial seed groupings of known germination percentage by appropriate selection of seeds from an unevenly germinating seed source. All three procedures were effective in identifying those processes associated with initial germination. The best synchronization was obtained with method (i). Germination, in contrast to imbibition, was signalled by a significant drop in inorganic phosphate levels, followed by a later rise as seed reserves of phytate were mobilized for seedling development. Differences in the rates of mobilization of acid-soluble phosphorus compounds were apparent between cultivated oats and genetically non-dormant wild oats.