Abstract: In order to improve the effect of hand-pollination in hybridization of Zinnia elegans the stigma receptivity and pollen longevity were tested. The studies were put in practice connecting the benzidine-H2O2 testing stigma receptivity , pollen germination test in vitro and the experiment of hand-pollination. The results show that Zinnia elegans flowers at 8:30-16:00 in daytime, pollen viability is for 18h. When it flowers, the stigmas of florets stand upright and keep high turgidity for 7~10 days. The benzidine-H2O2 test shows that the Stigmatic Pollen Receptivity for 1~3d, 4~6d and 10d are 79.9%~83.1%, 56.1%~63.0% and 56.1%~63.0% respectively, and there is an obvious difference for the stigmatic pollen receptivity between 1~6 d and 7~10 d. The experiment of hand-pollination shows that the seed set of the丫 stigma phase, the tip of 丫 slightly curling stigma phase and columnar stigma phase is 76.3%、48.5%,36.8% respectively. The seed set of no-treatment, detruncating one lob of stigma and style of detruncating stigma is 48.8%,30.9%,19.9% respectively, this indicates the stigma top with hair and its big surface is in favor of seeding, and detruncating stigma by hand-pollination also may seed. We should pollinate every other day at 10:00-16:00 daytime during flowering season to insure good seed set.

Key words: Benzidine-H2O2 test, Zinnia elegans Jacq., Stigma receptivity, Stigma shape, Pollen viability, Seed set