Photoinhibition of Seed Germination in the Maritime Plant Matthiola tricuspidata

The three-horned stock, Matthiola tricuspidata (L.) R. Br. isa widespread annual plant of the Mediterranean sandy shores.Its seeds are dark germinating and negatively photosensitive,in accordance with our previous findings for a number of othermaritime plants. Full germination was obtained at a wide rangeof temperatures (5-25 °C) in the dark. Inhibition of germinationunder light of various spectral qualities could be generallycorrelated, negatively and positively, respectively, with phytochromephotostationary state (ø) and relative cycling rate ofphytochrome (H). The inhibition of germination by white (fluorescent),blue and far-red light, applied either continuously or intermittently,consistently showed a linear dependence upon the logarithm ofthe flux density of the irradiation. The resulting photoinhibitioncurves had parallel slopes and, compared to those of other maritimeplants, they were shifted to higher flux densities, Continuousblue or far-red irradiations, both establishing a similar øvalue (0·26), resulted in statistically similar regressioncurves, thus favouring the hypothesis that phytochrome is thesingle photoreceptor in the photoinhibition of seed germination.Copyright1994, 1999 Academic Press Matthiola tricuspidata (L.) R. Br., three-horned stock, seed germination, light, photoinhibition, phytochrome