Light and nitrate interaction in phytochrome-controlled germination ofPaulownia tomentosa seeds |
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Authors: | D Grubi?i? R Konjevi? |
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Institution: | (1) Institute for Biological Research “S. Stanković” and Institute for Botany, Faculty of Science, University of Belgrade, 29. novembra 142, Y-11060 Belgrade, Yugoslavia |
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Abstract: | Pulsed light and nitrate exhibit an interactive effect on the germination ofPaulownia tomentosa Steud. seeds that require long periods of light irradiation. Two pulses of red light (R), separated by an adequately long
dark interval, substitute for continuous prolonged irradiation. A far-red (FR) pulse given at the beginning of the dark interval
inhibits germination, while it has no effect if given at the end. The requirement for certain ratios of the far-red-absorbing
form of phytochrome/total phytochrome (Pfr/Ptot) differs when a FR+R-pulse is given as the first or second of two pulses (FR+R or R) separated by a dark interval. An equal
decrease of the Pfr/Ptot ratio leads to a more pronounced decrease in germination when the pulse of the same FR+R ratio is given as the second pulse
at the end of the dark interval. The length of dark interval between light pulses needed for maximal germination, differed
in (i) seeds with a natural requirement for long periods of light irradiation from that in (ii) seeds with their long light
requirement imposed by two weeks of imbibition in darkness or by (iii) imbibition in 40% heavy water. However, a single R
pulse was sufficient to induce a high percentage of germination if the seeds were supplied with KNO3 (10 mM) from the onset of imbibition up to the onset of light. This effect decreased with a delayed time of application,
and was prevented if FR preceded the KNO3 application.
We dedicate this paper to Professor Hans Mohr on the occasion of his 60th birthday |
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Keywords: | Light and germination Nitrate and seed germination Paulownia Phytochrome and seed germination Seed germination (light nitrate) |
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