Abstract:By understanding the causes of seed dormancy of Phoebe sheareri, mechanical, acid-alkali corrosion and lamination treatment (5 ℃-25 ℃) were used to study the best methods to relieve seed dormancy. The results showed that the low permeability of seed coat was the main reason for inhibiting seed germination, and the seed dormancy type was physical dormancy. Acid and alkali corrosion treatments could not effectively break seed dormancy. After the seeds were treated with concentrated sulfuric acid and sodium hydroxide for different time (1-25 min), the germination rate was increased by 33%-55%, but the seeds were seriously damaged, and the decay rate was as high as 30%-97%. Both mechanical treatment and stratification treatments could effectively break seed dormancy, and removing whole seed coat by mechanical treatment had the best effect, and seed germination rate and germination potential increased by 99.33% and 76.00%, respectively. But this method was time-consuming and laborious. The seeds under 25 ℃ warm stratification for 45 d, 25 ℃/15 ℃ and 5 ℃/25 ℃/5 ℃ variable temperature stratification for 60 d could effectively promote germination, with the germination rate and germination potential increased by 89%-93% and 79%-83%, respectively, and there were no obvious differences in germination rate and germination potential among these types of stratification. However, compared with warm stratification, variable temperature stratification requires longer stratification time and higher seed decay rate. Therefore, 25 ℃ warm stratification for 45 d was the optimal way for breaking seed dormancy of P. sheareri.
