Pregerminated snapdragon seed was damaged to different extents by low-temperature storage for 4 or 8 days in 3 hydrophilic gels or deionized water. Poststorage viability and vigor decreased as a result of storage, but for apparently different reasons. Medium pH was correlated with poststorage vigor, whereas the gas-exchange capacity of the storage media was correlated with poststorage viability. Seed germination and radicle elongation within the gel was also stimulated when the gas-exchange capacity of the storage medium was increased. Enzymatic generation of oxygen within the gel increased both seed germination and radicle elongation, which suggests that the oxygen diffusion rate specifically was limiting these phenomena.