Abstract: By using the techniques of laboratory bioassay, this paper studied the effects of Descurainia sophia extract on the germination rate, germination index, vigor index, root length, shoot height, fresh weight, and dry weight of wheat, and measured the contents of MDA, Chla/Chlb and carotene as well as the karyokinesis index of 5 more sensitive wheat strains. The results showed that D. sophia extract had allelopathic effects on all test wheat strains, though the responses of the strains were significantly different. The test 3 physiological indices of 5 more sensitive wheat strains suggested that the action spot of the allelopathic substances of D. sophia might be the cell membrane of wheat, and the measurement of karyokinesis index indicated that D. sophia extract had inhibitory effects on wheat karyokinesis.

Key words: Waterlogged land, Step divergence, "Development in a step way" model