Four replicates of 25 freshly collected seeds each were placed in 9 cm diameter glass Petri dishes on filter paper moistened with distilled water and placed incubators equipped with a cool, white
fluorescent light (HPG-280B, Har’erbin, China) providing a photosynthetic photon flux density (PPFD) measured with LI-1400 Data logger (LI-COR, USA) of approximately 44 mmol m2 s1 over the waveband 400–700 nm. Seeds were exposed to a daily 14 h daily photoperiod at constant temperatures of 10, 15, 20, 25, 30, 35, and a daily 14 h fluctuating cycle of 20/30 ℃. Germination counts were made daily for 30–80 days depending on germination rate in relation to temperature. At the end of a 60-day incubation period at 10 ℃, seeds that had not germinated were transferred to 25 ℃ for 20 days. In addition, we compared germination under light and continuous dark at 25 ℃ using a green safe light to examine seeds incubated in darkness. Distilled water was added as required to ensure that moisture was non-limiting for germination. Seeds were recorded as germinated when the protruding radicle was2 mm in length (Tang and Long, 2008).