Photosensitivity of Rumex obtusifolius seeds for stimulation of germination: Influence of light and temperature |
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Authors: | Richard E Kendrick Gerda H Heeringa |
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Institution: | Plant Physiological Research, Agricultural Univ., Generaal Foulkesweg 72, 6703 BW Wageningen, The Netherlands. |
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Abstract: | A population of Rumex obtusifolius L. seeds imbibed for 24 h at 25°C exhibits a sigmoid logarithmic fluence-response relationship for stimulation of germination by red light (R), 11.0 μmol m?2 being necessary for 50% of the response. After 24 h imbibition at 35°C the fluence-response relationship for stimulation of germination by R is biphasic. For 50% response the very sensitive phase (very low fluence-response) requires 4.7 ? 10?2μmol m?2 whereas the less sensitive phase (low fluence-response) requires 4.0 μmol m2. A few seconds of far-red light (FR) satisfies the germination requirement of the sensitive seeds after 24 h at 35°C. However, a longer period of FR (2 h) results in low germination. The fluence-response relationship for induction of these seeds by R is sigmoid, 4.8 μmol m?2 being necessary for 50% response, demonstrating that 2 h FR desensitizes the sensitive proportion of the seed population induced by 24 h at 35°C. A proportion of the seed population can be further sensitized by 60 min at 35°C following this desensitization. |
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Keywords: | Biphasic fluence response low fluence-response (LFR) phytochrome very low fluence-response (VLFR) |
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