Prelim inary Report on in V itro Pollen Germ ina tion of B etu la a lnoides

In this paper suitable germinatingmedia and optimized temperature for pollens of Betula alnoides Buch. Ham. exD. Don were screened out through comparison tests using all sorts of germinatingmedia with different concentrations of sugarand boric acid under a series of temperature conditions, and its pollen germination processwas characterizedwith pollens collected from four individuals. Itwas indicated that supplementing boric acid to sugarmedia could remarkably accelerate pollengermination of B. alnoides, the suitable media for pollen germination consist of 15% sucrose and 200mg. kg-1 boric acid indistilled water, and optimized temperature was 30 ℃ for this species. And under these good conditions, the pollen germination rate and pollen tube length became stabilized after three hours and seven hours, respectively.