Solute Leakage from Artificially Aged Soybean Seeds after Imbibition1

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Abstract
It is known that aged seeds release more solutes upon hydration than unaged seeds. Previous studies of this response have utilized measurements of leakage during imbibition, which combine changes in leakage due to imbibitional stress with changes due to the aging response. We have examined the leakage characteristics in response to accelerated aging after virtual completion of a gentle hydration. Solute leakage from imbibed soybean cotyledons increased with accelerated aging in a linear manner in the range over which vigor was depressed. The UV absorbing solutes that leaked from these seeds included a group with a molecular weight (MW) of over 2000 and another group of MW less than 500. The MW profile of leaked compounds reflected changes in butanol‐extractable solutes with accelerated aging. The decline in seed vigor was associated with the lowering of the level of low molecular weight compounds in the cotyledonary cells. Increases in leakage with accelerated aging were closely associated with increases in areas containing damaged cells as evidenced by staining with Evans Blue. These findings indicate that even when hydration stress is minimized, a major contribution of the A260 detected solutes leaking from soybeans after accelerated aging is from cells which had experienced massive membrane damage.