Primary Study On The Germination Of Tree Peony Seeds

Seedling production is an important part of peony industry. Germination from seeds to seedlings takes at least 6 months in field Condition with a relatively low seedling rate of 60%, so the theoratical problem lays on high germination rate combined with shorter duration and higher regularity. The gernination characteristics and epicotyl dormancy releasing of P.ostii'Feng Dan', P.rockii hybrids and P. szechuanica are studied from several aspects: GA₃ treatment, controlled chilling treatment, different harvest time and storage duration, Co60-γray radiation, and the results are as follows:1. GA₃ treatment advanced the first rooting time and accelerated the rooting process effectively, but at the same time brought down the rate of taproot more than 40mm long, as well as the number of lateralroot more than 10mm. GA₃ at low density can promote the rooting rate while high density inhibite: 0～200mg/LGA₃ treatment for P.ostii'Feng Dan'and 0～300 mg/LGA₃ treatment for P.rockii hybrids increased their rooting rates, but when the density reached 300 mg/LGA₃ and above, the rooting rate was lower than CK.2. Either controlled chilling treatment or GA₃ treatment can release the epicotyl dormancy for P.ostii'Feng Dan', and P.rockii hybrids, but GA₃ treatment has no effect at all for P. szechuanica, who requires a very strick limit of chilling duration. The germination rate of P. szechuanica reaches more than 60% when the chilling duration exceed 90 days; in contrast, it almost down to 0 when chilling duration less than 60 days, and GA₃ treatment without chilling is tend to cause part of the seeds death by mildewing.3. For P.ostii'Feng Dan'and P.rockii hybrids seeds, GA₃ treatment can advance the first sprouting time, increase germination rate, but at the same time prolong the group sprouting duration, decrese the germination index and regularity. The germination rate is in positive correlation with GA₃ density when chilling duration less than 21 days, and negative correlation when more than 21days.4. Maturity period and optimal harvest time of P.ostii'Feng Dan'and P.rockii hybrids seeds is determined: when the colour of follicular friut is crab spawn-yellow, carpodermis is begin to craze, till the colour of spermoderm darken from brown to dark brown. Liquid water content is between 30%--60% and the germination rate is above 90%. During this period of time, the liquid water content of the seeds begin to decrease, the dry weight and the thousand kernel weight increse to its maximum point.5.Co60-γradiation has remarkable inhibitive effects on P.ostii'Feng Dan'and P.rockii hybrids seeds. The first rooting day and the first sprouting day is prolonged obviously. Germination rate can reaches 80% within the 0～20Gy dosage, but combined with a clearly decreased germination index, reqularity and prolonged duration.