Soybean Seed Imbibition: Water Absorption by Seed Parts

<jats:p>Seed imbibition is a critical stage in successful soybean [<jats:italic>Glycine max</jats:italic> (L.) Merr.] crop establishment. This study investigatesoybean seed imbibition with emphasis on absorption of water by the seed parts (seed coat, embryonic axis, cotyledons, and whole seed). Mter 72 h imbibition, the embryonic axis was the most hydrated portion of the seed possessing greater than 50 g kg<jats:sup>−1</jats:sup> fresh weight more water than any other seed part. The embryonic axis also hydrated more than the cotyledons in a high relative humidity environment when exposed as separated parts. Using polyethylene glycol 8000 as an osmotic agent, the seed coat, cotyledons, and whole seed contained a moisture content of approximately 550 g kg<jats:sup>−1</jats:sup> fresh weight and the embryonic axis 700 g kg<jats:sup>−1</jats:sup> fresh weight when germination (radicle emergence but less than 1.0 cm in length) occurred. while the cotyledons and embryonic axes of accelerated aged seeds did not differ in liquid moisture uptake from nondeteriorated seeds, the axes from accelerated aged seeds absorbed less water than the unaged controls when the seed parts were hydrated at 100% relative humidity (RH). These studies show that the embryonic axis hydrates more than the cotyledons, identify the level of moisture in the embryonic axis at which soybean seed germination is observed, and indicate that deteriorated seeds hydrate in a manner similar to nondeteriorated seeds in liquid water but that differences in the axes are detectable when hydrated in a high humidity environment.</jats:p>