Drying of seeds of Agropyron desertorum (Fisch. ex Link) Schult. did not result in breakdown of α-amylase nor impair the ability of seeds to resume its synthesis when moistened again. β-Amylase activity did not change during 5 days of germination at a water potential of 0 atmosphere nor during 40 days of incubation at −40 atmospheres. Seeds synthesized α-amylase at 0, −20, and −40 atmospheres, but not at −60 atmospheres. At 0 and −20 atmospheres, the log of α-amylase activity was linearly related to hastening of germination. But at −40 atmospheres, seeds synthesized α-amylase during a time when there was little hastening of germination. Thus, it appears that other biochemical reactions are less drought-tolerant than synthesis of α-amylase. It is concluded that inhibition of α-amylase synthesis is not a controlling factor in the germination of these seeds at low water potentials.
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