Seed Dormancy in Red Rice : VIII. Embryo Acidification during Dormancy-Breaking and Subsequent Germination

Exposure of dehulled, dormant red rice (Oryza sativa) seeds to dormancy-breaking treatments (10 mm sodium nitrite, 20 mm propionic acid, 30 mm methyl propionate, 40 mm propionaldehyde, or 70 mmn-propanol) induced tissue pH acidification during chemical contact at least 12 h before visible germination. During chemical contact, the onset of embryo acidification occurred before or coincident with the chemical contact interval necessary for subsequent germination. Upon seed transfer to H(2)O following chemical contact, embryo pH also decreased coincident with visible germination. During this period, the percentage of germination and embryo pH were closely linked irrespective of the dormancy-breaking compound used. Therefore, tissue acidification during the breaking of seed dormancy and the germination process may be analogous to similar tissue pH changes associated with the termination of developmental arrest in other multicellular systems, such as brine shrimp cysts and nematode larvae.