Effects Of Herbicides On Sexual Reproduction Of Ceratopteris Pteridoides And Vallisneria Natans

The effects of two herbicids bensulfuron methyl and quinclorac on gametophyte development and sexual differentiation of Ceratopteris pteridoides and on pollen germination of Vallisneria natans and quinclorac on sporophyte development of Ceratopteris pteridoides were studied in this thesis. The effects of herbicides pollution on the sexual reproduction of non-target aquatic plants were assessed. Specific conclusions are as follows:1 Bensulfuron methyl and quinclorac both dose-dependently inhibited the gametophyte growth of C. pteridoides .The 50% effect concentration (EC₅₀) of the two herbicides were 0.000086 mg.L^-1 and 0.48 mg.L^-1 respectively with gametophyte area as endpoint. The EC₅₀ for bensulfuron methyl was below the reported environment concentration .These results suggest that bensulfuron methyl contamination in the environment is expected to affect the gametophyte growth of C. pteridoides. Moreover, due to gametophyte growth was inhibited the hermaphrodite gametophyte ratio and archegonium were reduced and archegonium differentiation was delayed gradually.2 Quinclorac at 1 mg.L^-1 and higher concentrations induced gametophytes marginal mature cells into dedifferentiatied unorganized cells .At low concentrations, these cells quickly developed into new gametophyte and formed normal archegonium. The new formed gametophytes were usually above water which made the fertilization more difficult. At high concentration of 10 mg.L^-1 gametophyte cells continued to divide until gametophyte died.3 Quinclorac at 1mg.L^-1 and higher concentrations induced embryo deformity and sporophyte abnormal growth. 4 Calcium, boron, sucrose did not promote pollen germination of V. natans in vitro.Quinclorac and bensulfuron methyl at low concentrations did not affect the pollengermination.