Dormancy in the Seed of Western Wheatgrass (Agropyron smithii, Rydb.)

As is the case with many of the native grass species, western wheatgrass can at times possess a high amount of seed dormancy. This dormancy makes the determination of pure live seed difficult. Consequently, laboratory methods have been sought to completely break this dormancy in order to obtain a true determination of seed viability. Such methods as embryo excision, lemma and plea removal, caryopsis clipping, alternating temperatures, and others have been used with varying success. The method now employed by the South Dakota State Seed Laboratory to determine the viability of ungerminated grass seeds is the tetrazolium test. After the 28-day germination period, the ungerminated seeds are bisected longitudinally and placed in 1.0% tetrazolium solution for four hours. At the end of that period the seeds which have red or pink embryos are considered dormant seeds. The rest are considered dead. The purpose of this study was to attempt to determine the possible cause of the induction of dormancy in western wheatgrass seeds and assess the effects of alternate seed treatment methods on the breaking of this dormancy