Prevention of imbibitional injury in low vigor soybean embryonic axes by osmotic control of water uptake

Deterioration of soybean Glycine max (L.) Merr. cv. Essex] seeds during accelerated aging at 41°C and 100% relative humidity predisposes the embryonic axis to injury during the initial period of imbibition. This injury was prevented or greatly reduced in severity when excised axes were imbibed on blotters containing 30% polyethylene glycol which slowed the rate of water uptake and when axes were pre-equilibrated to a high moisture level. Rates of water uptake by "high"(no treatment) and "low vigor"(accelerated aged) excised axes were identical. However, high vigor axes tolerated rapid water uptake during early imbition, whereas low vigor axes did not. Leakage of electrolytes during early imbibition was nearly six times greater in low than in high vigor axes. Polyethylene glycol significantly reduced the leakage of electrolytes from both low and high vigor axes. The data are in agreement with the hypothesis that seed deterioration in soybeans involves membrane changes which may predispose embryonic tissues to injury during imbibition. Reduction of the rate of water uptake during the initial period of imbibition would allow extra time for membrane repair or rearrangement, thus permitting the tissues to develop in a more orderly manner. The data indicate that deterioration in soybean seeds involves, at least in part, a decrease in ability of seed axes to tolerate rapid water uptake at the start of imbibition and that this weakness may be compensated by osmotic control of water uptake.