Abstract:Objective:To substantiate the effect of space conditions on medicinal plants.Methods:The seeds of Agastache rugosa were set up in retrievable satellites. After returning to earth, the changes of isozymes of peroxidases, esterase and soluble proteins were studied.Results:The peroxidase activity and protein content of the weightless group were a little lower than those of the earth controlled group, while these two items of the hit group were higher than those of the earth controlled group.The electrophoresis patterns of isoperoxidases and isoeasterase of these three groups, as well as the protein patterns of the weightless group and the earth controlled group were found alike. But the protein patterns of the hit group were different from those of the other tow groups.Conclusion:The effect of weightlessness is smaller than that of the high energy heavy ions on Agastache rugosa.Different plants have different susceptibility to space conditions.