PEG could significantly improve the germination energy of alder seed, with its extent relating to the maturity level of seed, no effect of PEG was found on the relative higher maturity seed of alder.

• PEG能显著提高桤木种子的发芽势,提高发芽率的效用与种子的成熟度有关,对成熟度高的种子影响不显著;