Possible mechanisms of afterripening in Xanthium seeds |
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Authors: | Yohji Esashi,Maria Ogasawara,Ryszard Gó recki,A. Carl Leopold |
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Affiliation: | Dept of Biological Science, Tohoku Univ., Kawauchi, Aobaku, Sendai 980, Japen;;Dept of Plant Physiology and Biochemistry, Univ. of Agriculture and Technology, Oldzlyn, Poland;;Boyce Thompson Institute, Cornell Univ., Ithaca, NY 14853, USA. |
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Abstract: | Breaking dormancy in some seeds requires a period of dry storage. In the seeds of Xanthium pennsylvanicum Wallr., the process of afterripening proceeds optimally at water contents between 7 and 14%: this range of dehydration can be identified with water binding region 2, in which water is bound with low enthalpy. At water contents below 7%. Seeds remained primarily dormant over 3 years. Attempts to alter the afterripening with atmospheres of elevated nitrogen showed no effect. and with oxygen there was no consistent effect. There were no changes is osmotic value of the seed sap, or in its sugar or amino acid contents. We speculate that afterripening in Xanthium may involve some nonenxymatic reactions which remove substances which inhibit germination. Candidates for these reactions include the Amadori and Maillard reactions. |
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Keywords: | Afterripening relative humidity seed dormancy seed germination water content Xanthium pennsylvanicum. |
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