Dormancy-release, germination and seedling growth of Paeonia ostii ‘Fengdan’ seeds under measures of physical and chemical treatment and sowing

Paeonia ostii 'Fengdan', a woody oleaginous plant native from China, is considered an oil crop with economic potential. However, a low germination rate was still a restriction for Paeonia ostii 'Fengdan' production. The present research evaluated the germination, rooting and physiological characteristics of seedlings of Paeonia ostii 'Fengdan' in response to different physical treatments and the application of exogenous chemicals. Results indicated that seeds stored in sand at room temperature, and soaked in water for 3 days prior to planting, had a beneficial effect on hypocotyl dormancy-breaking. The rate of rooting and root growth of Paeonia ostii 'Fengdan' were significantly improved with 5 cm sowing depth in 15-20℃ soils. Compared with other sowing depths, the rooting percentage was significantly increased by 1.19% (2.5 cm), 0.98% (7.5 cm) and 1.47% (10 cm), respectively. Epicotyl dormancy was relieved when taproot length reached 50 mm. Soaking seeds in 0.76 mmol/L 5-aminolevulinic acid for 48 hours had the greatest beneficial effect on seed germination and seedling growth, the germination percentage was significantly increased by 4.25% (24 h) and 5.08% (72 h) compared with other treatments. While seed soaked in 10 mmol/L sodium nitroprusside for 48 hours also exhibited enhanced seedling growth, and the germination percentage was significantly increased by 4.36% (24 h) and 7.40% (72 h). Those results benefited seed germination and seedling growth of Paeonia ostii 'Fengdan' which could suggest the promotion of its industrial values and productive potentials. The mechanism of seed breaking dormancy and germination of Paeonia ostii 'Fengdan' needs further study.