Abstract:

Aims Betula albo-sinensis occurs in the middle to high elevations of Taibai Mountain, China where its forests have regeneration barriers. We studied the germination and physiological characteristics of B. albo-sinensis seeds to investigate natural regeneration.

Methods We observed 2 400 seeds of B. albo-sinensis without pericarp and recorded germination rates. We studied germination rates under different photosynthetically active radiation (PAR) and photoperiod (high light: PAR = 464.7 µmol photons ·m^-2·s^-1, 12 h·d^-1; middle light: PAR = 233.8 µmol photons ·m^-2·s^-1, 12 h·d^-1; low light: PAR = 233.8 µmol photons ·m^-2·s^-1, 0.5 h·d^-1), different day/night temperatures (25/20 ℃, 20/15 ℃ and 15/10 ℃) and with and without pericarp. We also recorded germination rates without light, under different culture media (soil and sand) and mulch (broad leaf, needle leaf and mixed leaf) or covered with leaf (broad leaf and mixed leaf).

Important findings We found that 54.29% of the seed is full in the fully maturated ones. The optimum germination temperature is 25/20 ℃, and few seeds germinated under 15/10 ℃. Germination rates under middle light were highest, and there was no seed germination under no light. Shelling the pericarp could improve germination rates. Germination rates declined in the groups covered with mulch, but there was no significant difference among culture media. We conclude that B. albo-sinensis seed germination depends on natural disturbances in its natural environment.

Key words: Betula albo-sinensis, seed, light, temperature, natural regeneration