Nitrogenous compounds, such as potassium nitrate, potentiate germination of different species of light-requiring seeds. Using light-induced Arabidopsis thaliana seed germination as a model system, our data suggested that only phytochrome A (phyA)-specific induced germination was affected after the exogenous application of nitrates, different nitric oxide (NO)-donors (such as organic nitrates) or sodium nitroprusside. The stimulative effect was very pronounced. Treated seed samples reached maximal germination after very short periods of red-light irradiation. To a far lesser extent, these substances affected phytochrome B (phyB)-specific induced germination. In phyB-specific induced germination, potassium nitrate was most effective, but germination percentages never exceeded 50%. The least effective was sodium nitroprusside, which practically did not affect phyB-specific induced germination. These results were confirmed using corresponding phytochrome mutants.
