Seed dormancy and germination characteristics of Osteomeles schwerinae, a riparian plant endemic to the Hengduan Mountains and adjacent regions

Osteomeles schwerinae, an endemic plant with ecological restoration functions from the hot/warm-dry river valleys of the Hengduan Mountains and adjacent regions, has low seed germination in cultivation. This study attempted to improve seed germination by testing the effect of several treatments including dry after-ripening (DAR), GA3, light and temperature treatments for seeds from three populations. DAR increased germination at 25/15°C but not at 15/5°C, as compared with fresh seeds. DAR was sufficient to break dormancy; GA3 could not significantly increase germination percentage, indicating that seeds of O. schwerinae appear to have non-deep physiological dormancy. After the dormancy is broken, temperature significantly affects germination. Seeds germinated significantly better at higher temperatures (20-25°C) than at lower (< 15°C) and extreme high temperatures (> 30°C). A base temperature for germination (Tb) of 4.9-9.3°C and a thermal time requirement for 50% germination (θ50) ranging from 158.7 to 217.4°Cd were identified for non-dormant DAR seeds, depending on the population. This study provides a theoretical basis for dormancy-break and germination of O. schwerinae seeds.