Low-temperature stratification strategies and growth regulators for rapid induction of Paris polyphylla var. yunnanensis seed germination

The seeds of Paris polyphylla var. yunnanensis are deeply dormant, and they remain dormant for 18 months or longer in their natural environment. Periodic exposure of the seeds to a low-temperature of 4°C broke the dormancy in about 16 weeks (112 days). The most effective temperature stratification scheme was an interval of 14 days at 4°C and 14 days at 22°C. Both GA3and ethephon significantly enhanced the germination rate during the stratification treatment. The seed coat, particularly the mesophyll outer layer of the seed coat, strongly inhibited the germination. With removal of the seed coat and exposure of the uncoated seeds to 600 mg/l GA3for 48 h before the temperature stratification of 14 days at 4°C and 14 days at 22°C for 112 days, a germination percentage as high as 95.3% of the seeds was attained in about 160 days.