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Abstract [Objectives]This study was conducted to investigate the effects of different treatments on rooting and germination of Paeonia rockii T. Hong et J. J. Li seeds.[Methods]Different stratification time and temperatures and different GA3 concentrations and treatment time were set to screen the optimum treatment method for promoting seed rooting and germination.[Results]The rooting rate was the highest when the seeds were subjected to 30 d of stratification treatment in an incubator at 25→， and treated with 300 mg/L GA3 for 24 h. Soaking the seeds with 300 mg/L GA3 for 24 h combined with 30 d of stratification treatment was most beneficial to germination， and the germination rate was over 90%.[Conclusions]This study provides technical guidance and basic information for the rooting and germination of P. rockii seeds
Key words Paeonia rockii T. Hong et J. J. Li seeds; Stratification treatment; Gibberellin treatment; Rooting rate; Germination rate
Paeonia rockii T. Hong et J. J. Li is a perennial deciduous shrub of the genus Paeonia， which is a unique endangered species in China， as well as the most threatened species among all wild peony[1]. In 1987， it was listed as a national tertiary protected plant[2]， and has been listed in the National Key Protected Wild Plants List. The P. rockii is an important member of the Chinese peony family. Its wild ancestor is an important original species of Chinese peony cultivars. The northwest （P. rockii） peony cultivar group evolved with P. rockii as the main genetic germplasm is the second largest peony group among Chinese peony， only second to P. cathayana[3]. This cultivar group has obvious purple or purplered spots on the base of the petal; and it has strong growth and strong tolerance to cold， drought， alkali and poor fertility， and has high ornamental and breeding value[4]. Furthermore， due to high yield， high oil content， high quality and low cost of peony oil， the development of P. rockii as a woody oil crop has been promoted， and the economic value and market development prospects have also promoted the increase of demand for seed reproduction and seedling production of P. rockii[5]. Peony oil also contains nutrients such as paeonol， peony saponin and peony polysaccharide， which have blood fat and blood pressure lowering， antiinflammatory， antiaging， anticancer and anticancer effects[6].
Because of the double dormancy of the epicotyl and hypocotyl of P. rockii[7-8]， the seed germination is difficult， the seedling cycle is longer， and the emergence rate is not high， which seriously affects the development of the peony industry. Studies have shown that GA3 can break the hypocotyl dormancy of the seeds of wild peony such as P. ludlowii and P. delavayi， and cultivated peony P. suffruticosa and P. ostii ‘Fengdan’ seeds and promote rooting[9-12]， and low temperature and GA3 treatment can break the epicotyl dormancy of P. ludlowii， P. delavayi and P. ostii[10-14]， and significantly promote seed germination and seedling growth. At present， few studies have been conducted on the epicotyl germination characteristics of P. rockii seeds. Highlevel studies have found that soaking the rooted seeds of P. ostii with 200 mg/L GA3 for 2 h can shorten the germination time， but had no obvious effect of breaking the hypocotyl dormancy of P. rockii seeds[15]. Fan et al.[16]found that the treatment of rooted P. ostii seeds with 200 mg/L GA3 could effectively break its epicotyl dormancy， so that the germination rate was 90.1% and the germination time was shortened to 45 d. The temperature required for rooting of P. rockii seeds has not been reported. Therefore， in this study， different stratification treatment time and temperatures and different GA3 concentrations and treatment time were investigated to obtain the most favorable way for seed rooting and germination. This study will provide some technical guidance for the improvement of P. rockii seed germination and the promotion of seedling growth and provide some basic data for further establishment of systematic P. rockii seed germination technology and seedling production technology.
Materials and Methods
Materials
The experiment was carried out in the greenhouse of College of Agriculture， Yanbian University in 2016. The seeds of P. rockii were selected as the test materials. Mature black fruit seeds were picked， and the collected seeds were placed in a semishadow condition to dry them. Full seeds were selected for use.
Experimental methods
Seed treatment
Full round P. rockii seeds were pretreated. Washing of seeds： The seeds were washed with running water repeatedly. Selection of seeds： The peony seeds were soaked with distilled water for 3-4 h. Surface disinfection： Peony seeds were soaked in 0.5% potassium permanganate solution for 30 min for disinfection. In this process， constant stirring was required to make the disinfection sufficient， followed by rinsing with water. The disinfected P. rockii seeds were mixed with river sand sand subjected to high temperature sterilization according to a volume ratio of 1≥3， and an appropriate amount of water was added to a humidity which was 50% of the maximum water holding capacity of the sand （when held with hands， no water dripped off， and when released， the sand came loose with a touch）， to keep the sand wet. The mixture was placed in a low temperature condition at 4 for stratification. The stratification time was set to 4 treatments （10， 20， 30， 40 d）， and a control （0 d， CK） was also set. Each treatment included 100 seeds with three replicates.
Observation of seeds
The P. rockii seeds were sown in a petri dish with moist filter paper， and cultured in a constant temperature incubator. The temperature gradient of the culture was （10， 15， 20， 25， 30）， and the rooting condition was observed periodically， to obtain the optimum temperature for P. rockii rooting.
Experimental setting
Five different concentrations of GA3 treatments and one control treatment were set. The GA3 concentrations were 100， 200， 300， 400 and 500 mg/L， respectively， and water was used as the CK. Seeds were soaked with the solutions in a volume 3 times of the seeds， and treated for 0， 12， 24， 36， 48， and 72 h， respectively. The rooting adopted the culture dish method. 100 seeds were selected for each treatment， with three replicates. The rooting of P. rockii seeds was observed. Treatment after rooting
After the seeds were rooted， the seeds subjected to 30 d of stratification treatment （with the highest rooting rate） were soaked with 0， 100， 200， 300， 400 and 500 mg/L GA3， respectively. The treatment time was 12， 24 and 36 h， respectively. The rooting time was recorded under the standard that the rhizome of the seeds was extended， and the germination time was calculated.
Rooting rate=（Number of rooted seed/Total number of seeds）≠100%
Germination rate=（Number of normally germinated seeds/Number of tested seeds）≠100%
Data processing
The data collected by this study were collated by Excel 2007， and the data obtained were analyzed by ANOVA with SPSS 20.0 software.
Results and Analysis
Effect of Lowtemperature stratification treatment time on rooting rate of P. rockii seeds
Different days of stratification treatment had different effects on the rooting of P. rockii seeds. When the stratification treatment was 30 d， the rooting rate was the best， reaching 83.4%， and the time for the root to break through the seed coat was the shortest， only 30 d. The seeds treated for 20 and 40 d had no big difference in rooting rate. The rooting rate of seeds without stratification was the lowest， only 53.5%， and the time for the root to break through the seed coat was longer， 107 d. It indicated that the stratification treatment was beneficial to the rooting of P. rockii seeds （Table 1）.
Effect of temperature on rooting of P. rockii seeds
Temperature has an important effect on rooting of P. rockii seeds. When the temperature was 25 and the relative humidity was （50÷5）%， the seed rooting rate was the highest， reaching 78.6%. When the temperature was 20， the rooting rate was 68.5%， which was lower than that at 25 by 10.1%. When the temperature was 30， the rooting rate was 58.4%， which was 20.2% lower than that at 25. If the temperature is too high or too low， rooting rate will be affected. Therefore， the optimal temperature for rooting of P. rockii seeds was 25 （Table 2）.
Effect of GA3 concentration on rooting of P. rockii seeds
Different GA3 concentrations and different treatment time had different effects on the rooting of P. rockii seeds. Under the condition of treating the seeds with 300 mg/L GA3 for 24 h， the rooting rate of P. rockii seeds was the highest， reaching 84.5%. It could be seen from the rooting time that all the concentrations could shorten the seed rooting time. The seeds free of treatment with GA3 had a rooting time of 107 d， and the rooting rate only reached 40.8%， indicating that GA3 treatment promoted the hypocotyl dormancy of P. rockii seeds. Effects of GA3 concentration and soaking time on germination of P. rockii seeds
The seeds subjected to 30 d of stratification treatment were treated with different concentrations of GA3 for 12， 24 and 36 h， respectively. The results showed that different concentrations of GA3 and different treatment time had significant effects on the germination rate of P. rockii seeds. When the seeds were treated with 300 mg/L GA3 for 24 h， the germination rate （seeds with a root length of 6-7 cm） reached over 90%. When the concentration of GA3 was higher than 300 mg/L， the germination rate of seeds decreased with the prolongation of soaking time. When the concentration of GA3 was less than 300 mg/L， the germination rate of seeds decreased with the prolongation of soaking time. It indicated that toohigh or toolow GA3 concentration will inhibit seed germination， and the longer the treatment time， the more obvious the inhibition effect.
Discussion
Seed reproduction is the only way to propagate wild P. rockii[17]， as well as the most common breeding method of P. rockii[18]. Seed dormancy usually refers to the phenomenon that viable seeds do not germinate under suitable germination conditions[19]. Studies have shown that the seed coat of P. rockii seeds is not the main reason for dormancy， because the seed coat has certain water permeability， and the most important reasons for hindering its germination are existence of seed germination inhibitor， incomplete embryo development and physiological postripening[20]. Stratification treatment is a method to relieve the dormancy of plant seeds， especially for seeds suffering from physiological dormancy caused by the existence of seed germination inhibitor and physiological postripening. In this study， it was found that P. rockii seeds can break hypocotyl dormancy through stratification. Gu[21]analyzed the effects of different low temperature treatments and gibberellin treatments on the dormancy of P. suffruticosa var. spontanea seeds， and pointed out the most suitable low temperature treatment conditions and the most suitable gibberellin concentration. Zhou et al.[22]believed that the treatment with 500 mg/L GA3 for 48 h could accelerate the rooting rate. In this study， the rooting rate was the highest when the concentration of GA3 was 300 mg/L. Yu et al.[23]believed that the combination of 14 d of low temperature with 500 mg/L GA3 was the best combination to promote seed germination and seedling growth of P. rockii. Lou et al.[24]found that soaking seeds with 300 mg/L GA3 solution can effectively promote early germination of rooted seeds. In this study， it was found that the seeds subjected to 30 d of stratification and 24 h of soaking with 300 mg/L GA3 had the highest germination rate. Conclusions
In this study， the rooting rate of P. rockii seeds subjected to 30 d of stratification treatment was the highest， reaching 83.4%， and the rooting time was the shortest. And the rooting rate reached the highest， of 84.5% when the seeds were soaked with 300 mg/L GA3 for 24 h. The required environmental conditions were also explored， and the results showed that the seed rooting was most beneficial at the temperature of 25. The study also explored the effects of different GA3 concentrations and treatment time on the germination of P. rockii. The results showed that when the concentration of GA3 was 300 mg/L and the treatment time was 24 h， the germination rate was the highest， reaching over 90%.
References
[1]JING XM， ZHENG GH， PEI YL， et al. A study on the relationship between seed germination of wild Paeonia rockii and P. szechuanica and their endangerment[J]. Biodiversity Science， 1995， 3（2）： 84-87. （in Chinese）
[2]FU LG， JIN JM. China Plant Red Data Book： Rare and Endangered Plants[M]. Beijing： Science Press， 1991. （in Chinese）
[3]CHENG FY， LI JJ， CHEN DZ， et al. Chinese Paeonia rockii[M]. Beijing： China Forestry Publishing House， 2005： 44-46. （in Chinese）
[4]CHENG FY， CHEN DZ. Studies on the selection and breeding of new hybrids from blotched tree peony （Paeonia rockii cvs.） and the cultivars classification of tree peony[J]. Journal of Beijing Forestry University， 1998， 20（2）： 27-32. （in Chinese）
[5]LIU X， LI CZ， TANG GG， et al. Germination characteristics of Paeonia rockii seeds[J]. Jiangsu Agricultural Sciences， 2016， 44（8）： 289-291. （in Chinese）
[6]ZHU XB， ZHAI WT， DONG XY， et al. Progress on chemical composition and function of peony seed oil[J]. China Oils and Fats， 2014， 39（1）： 88-90. （in Chinese）
[7]LI JJ. Chinese Paeonia suffruticosa Andr. and Paeonia lactiflora Pall.[M]. Beijing： China Forestry Publishing House， 1999： 1-2. （in Chinese）
[8]ZENG DX， YIN WL， ZHAO YQ， et al. Paeonia suffruticosa Andr. propagation technology[J]. Journal of Beijing Forestry University， 2000， 22 （3）： 90-95. （in Chinese）
[9]ZHENG XM， ZHOU YB， GU LP， et al. The properties of dormancy and germination of Paeonia suffruticosa[J]. Plant Physiology Journal， 1995， 31 （4）： 260-262. （in Chinese）
[10]CHENG FY， DU XJ. Effects of chilling and gibberellic acid on the seed germination and seedling growth in Paeonia ostii ‘Feng Dan’[J]. Acta Horticulturae Sinica， 2008， 35 （4）： 553-558. （in Chinese） [11]MA H， LI ZH， ZHANG YL， et al. Release of seed dormancy of Paeonia ludlowii[J]. Scientia Silvae Sinicae， 2012， 48（9）： 62-67. （in Chinese）
[12]LIU XX， ZHANG YL， MA H， et al. Studies on seed dormancy release of Paeonia delavayi[J]. Seed， 2013， 32（2）： 9-12. （in Chinese）
[13]LIN SM. Effect of different hormone and moistchilling on seed germination and seedling growth of Fengdan[D]. Nanjing： Nanjing Agricultural University， 2007. （in Chinese）
[14]QIAN XY. Physiological and metabolic changes in release of Fengdan seed dormancy by temperature and GA3[D]. Nanjing： Nanjing Agricultural University， 2009. （in Chinese）
[15]GAO SP， FAN BY， LIU GX， et al. Primary study on effect of epicotyls dormancy breaking of seeds of herbaceous peony and tree peony[J]. Northern Horticulture， 2008， 18805： 116-118. （in Chinese）
[16]FAN BY， GAO SP， SHI GA， et al. Study on the epicotyl dormancy breaking of seeds of peony （Paeonia suffruticosa Andr.） with GA3 and low temperature[J]. Seed， 2007（03）： 1-3. （in Chinese）
[17]CHEN HL， YANG YL， ZHANG XY， et al. Research progress on Paeonia suffruticosa Andr[J]. Hubei Forestry Science and Technology， 2013， 42（5）： 41-44. （in Chinese）
[18]GUO LP. Study on seed dormancy and dormancy release method[D]. Yangling： North West Agriculture and Forestry University， 2016. （in Chinese）
[19]ZHOU RC， YAO CH， PAN J， et al. Studies on characteristics of dormancy and germination of Paeonia rockii[J]. Hubei Agricultural Sciences， 2002（01）： 59-60. （in Chinese）
[20]JIN XM， ZHENG GH， PEI YL， et al. A study on the relationship between seed germination of wild Paeonia rockii and P. szechuanica and their endangerment[J]. Biodiversity Science， 1995， 3（2）： 84-87. （in Chinese）
[21]REN HY. Experimental study on seed germination and container seedling cultivation of Paeonia suffruticosa Andr[D]. Beijing： Beijing Forestry University， 2016. （in Chinese）
[22]ZHOU RC， YAO CH， PAN J， et al. Preliminary study on dormancy and germination characteristics of Paeonia rockii seeds[J]. Hubei Agricultural Sciences， 2002， 30（1）： 59-60. （in Chinese）
[23]YU L， ZHONG Y， WANG R， et al. Effects of gibberellic acid and chilling treatments on seed germination and seedling growth of Paeonia rockii hybrids[J]. Journal of Beijing Forestry University， 2015， 37（4）： 120-126. （in Chinese）
[24]LOU FF， ZHAO LS， LI ZY. Preliminary study on seed dormancy and germination characteristics of Paeonia lutea wild population on West Mount， Kunming[J]. Journal of Southwest Forestry College， 2007， 05： 34-37. （in Chinese）
Key words Paeonia rockii T. Hong et J. J. Li seeds; Stratification treatment; Gibberellin treatment; Rooting rate; Germination rate
Paeonia rockii T. Hong et J. J. Li is a perennial deciduous shrub of the genus Paeonia， which is a unique endangered species in China， as well as the most threatened species among all wild peony[1]. In 1987， it was listed as a national tertiary protected plant[2]， and has been listed in the National Key Protected Wild Plants List. The P. rockii is an important member of the Chinese peony family. Its wild ancestor is an important original species of Chinese peony cultivars. The northwest （P. rockii） peony cultivar group evolved with P. rockii as the main genetic germplasm is the second largest peony group among Chinese peony， only second to P. cathayana[3]. This cultivar group has obvious purple or purplered spots on the base of the petal; and it has strong growth and strong tolerance to cold， drought， alkali and poor fertility， and has high ornamental and breeding value[4]. Furthermore， due to high yield， high oil content， high quality and low cost of peony oil， the development of P. rockii as a woody oil crop has been promoted， and the economic value and market development prospects have also promoted the increase of demand for seed reproduction and seedling production of P. rockii[5]. Peony oil also contains nutrients such as paeonol， peony saponin and peony polysaccharide， which have blood fat and blood pressure lowering， antiinflammatory， antiaging， anticancer and anticancer effects[6].
Because of the double dormancy of the epicotyl and hypocotyl of P. rockii[7-8]， the seed germination is difficult， the seedling cycle is longer， and the emergence rate is not high， which seriously affects the development of the peony industry. Studies have shown that GA3 can break the hypocotyl dormancy of the seeds of wild peony such as P. ludlowii and P. delavayi， and cultivated peony P. suffruticosa and P. ostii ‘Fengdan’ seeds and promote rooting[9-12]， and low temperature and GA3 treatment can break the epicotyl dormancy of P. ludlowii， P. delavayi and P. ostii[10-14]， and significantly promote seed germination and seedling growth. At present， few studies have been conducted on the epicotyl germination characteristics of P. rockii seeds. Highlevel studies have found that soaking the rooted seeds of P. ostii with 200 mg/L GA3 for 2 h can shorten the germination time， but had no obvious effect of breaking the hypocotyl dormancy of P. rockii seeds[15]. Fan et al.[16]found that the treatment of rooted P. ostii seeds with 200 mg/L GA3 could effectively break its epicotyl dormancy， so that the germination rate was 90.1% and the germination time was shortened to 45 d. The temperature required for rooting of P. rockii seeds has not been reported. Therefore， in this study， different stratification treatment time and temperatures and different GA3 concentrations and treatment time were investigated to obtain the most favorable way for seed rooting and germination. This study will provide some technical guidance for the improvement of P. rockii seed germination and the promotion of seedling growth and provide some basic data for further establishment of systematic P. rockii seed germination technology and seedling production technology.
Materials and Methods
Materials
The experiment was carried out in the greenhouse of College of Agriculture， Yanbian University in 2016. The seeds of P. rockii were selected as the test materials. Mature black fruit seeds were picked， and the collected seeds were placed in a semishadow condition to dry them. Full seeds were selected for use.
Experimental methods
Seed treatment
Full round P. rockii seeds were pretreated. Washing of seeds： The seeds were washed with running water repeatedly. Selection of seeds： The peony seeds were soaked with distilled water for 3-4 h. Surface disinfection： Peony seeds were soaked in 0.5% potassium permanganate solution for 30 min for disinfection. In this process， constant stirring was required to make the disinfection sufficient， followed by rinsing with water. The disinfected P. rockii seeds were mixed with river sand sand subjected to high temperature sterilization according to a volume ratio of 1≥3， and an appropriate amount of water was added to a humidity which was 50% of the maximum water holding capacity of the sand （when held with hands， no water dripped off， and when released， the sand came loose with a touch）， to keep the sand wet. The mixture was placed in a low temperature condition at 4 for stratification. The stratification time was set to 4 treatments （10， 20， 30， 40 d）， and a control （0 d， CK） was also set. Each treatment included 100 seeds with three replicates.
Observation of seeds
The P. rockii seeds were sown in a petri dish with moist filter paper， and cultured in a constant temperature incubator. The temperature gradient of the culture was （10， 15， 20， 25， 30）， and the rooting condition was observed periodically， to obtain the optimum temperature for P. rockii rooting.
Experimental setting
Five different concentrations of GA3 treatments and one control treatment were set. The GA3 concentrations were 100， 200， 300， 400 and 500 mg/L， respectively， and water was used as the CK. Seeds were soaked with the solutions in a volume 3 times of the seeds， and treated for 0， 12， 24， 36， 48， and 72 h， respectively. The rooting adopted the culture dish method. 100 seeds were selected for each treatment， with three replicates. The rooting of P. rockii seeds was observed. Treatment after rooting
After the seeds were rooted， the seeds subjected to 30 d of stratification treatment （with the highest rooting rate） were soaked with 0， 100， 200， 300， 400 and 500 mg/L GA3， respectively. The treatment time was 12， 24 and 36 h， respectively. The rooting time was recorded under the standard that the rhizome of the seeds was extended， and the germination time was calculated.
Rooting rate=（Number of rooted seed/Total number of seeds）≠100%
Germination rate=（Number of normally germinated seeds/Number of tested seeds）≠100%
Data processing
The data collected by this study were collated by Excel 2007， and the data obtained were analyzed by ANOVA with SPSS 20.0 software.
Results and Analysis
Effect of Lowtemperature stratification treatment time on rooting rate of P. rockii seeds
Different days of stratification treatment had different effects on the rooting of P. rockii seeds. When the stratification treatment was 30 d， the rooting rate was the best， reaching 83.4%， and the time for the root to break through the seed coat was the shortest， only 30 d. The seeds treated for 20 and 40 d had no big difference in rooting rate. The rooting rate of seeds without stratification was the lowest， only 53.5%， and the time for the root to break through the seed coat was longer， 107 d. It indicated that the stratification treatment was beneficial to the rooting of P. rockii seeds （Table 1）.
Effect of temperature on rooting of P. rockii seeds
Temperature has an important effect on rooting of P. rockii seeds. When the temperature was 25 and the relative humidity was （50÷5）%， the seed rooting rate was the highest， reaching 78.6%. When the temperature was 20， the rooting rate was 68.5%， which was lower than that at 25 by 10.1%. When the temperature was 30， the rooting rate was 58.4%， which was 20.2% lower than that at 25. If the temperature is too high or too low， rooting rate will be affected. Therefore， the optimal temperature for rooting of P. rockii seeds was 25 （Table 2）.
Effect of GA3 concentration on rooting of P. rockii seeds
Different GA3 concentrations and different treatment time had different effects on the rooting of P. rockii seeds. Under the condition of treating the seeds with 300 mg/L GA3 for 24 h， the rooting rate of P. rockii seeds was the highest， reaching 84.5%. It could be seen from the rooting time that all the concentrations could shorten the seed rooting time. The seeds free of treatment with GA3 had a rooting time of 107 d， and the rooting rate only reached 40.8%， indicating that GA3 treatment promoted the hypocotyl dormancy of P. rockii seeds. Effects of GA3 concentration and soaking time on germination of P. rockii seeds
The seeds subjected to 30 d of stratification treatment were treated with different concentrations of GA3 for 12， 24 and 36 h， respectively. The results showed that different concentrations of GA3 and different treatment time had significant effects on the germination rate of P. rockii seeds. When the seeds were treated with 300 mg/L GA3 for 24 h， the germination rate （seeds with a root length of 6-7 cm） reached over 90%. When the concentration of GA3 was higher than 300 mg/L， the germination rate of seeds decreased with the prolongation of soaking time. When the concentration of GA3 was less than 300 mg/L， the germination rate of seeds decreased with the prolongation of soaking time. It indicated that toohigh or toolow GA3 concentration will inhibit seed germination， and the longer the treatment time， the more obvious the inhibition effect.
Discussion
Seed reproduction is the only way to propagate wild P. rockii[17]， as well as the most common breeding method of P. rockii[18]. Seed dormancy usually refers to the phenomenon that viable seeds do not germinate under suitable germination conditions[19]. Studies have shown that the seed coat of P. rockii seeds is not the main reason for dormancy， because the seed coat has certain water permeability， and the most important reasons for hindering its germination are existence of seed germination inhibitor， incomplete embryo development and physiological postripening[20]. Stratification treatment is a method to relieve the dormancy of plant seeds， especially for seeds suffering from physiological dormancy caused by the existence of seed germination inhibitor and physiological postripening. In this study， it was found that P. rockii seeds can break hypocotyl dormancy through stratification. Gu[21]analyzed the effects of different low temperature treatments and gibberellin treatments on the dormancy of P. suffruticosa var. spontanea seeds， and pointed out the most suitable low temperature treatment conditions and the most suitable gibberellin concentration. Zhou et al.[22]believed that the treatment with 500 mg/L GA3 for 48 h could accelerate the rooting rate. In this study， the rooting rate was the highest when the concentration of GA3 was 300 mg/L. Yu et al.[23]believed that the combination of 14 d of low temperature with 500 mg/L GA3 was the best combination to promote seed germination and seedling growth of P. rockii. Lou et al.[24]found that soaking seeds with 300 mg/L GA3 solution can effectively promote early germination of rooted seeds. In this study， it was found that the seeds subjected to 30 d of stratification and 24 h of soaking with 300 mg/L GA3 had the highest germination rate. Conclusions
In this study， the rooting rate of P. rockii seeds subjected to 30 d of stratification treatment was the highest， reaching 83.4%， and the rooting time was the shortest. And the rooting rate reached the highest， of 84.5% when the seeds were soaked with 300 mg/L GA3 for 24 h. The required environmental conditions were also explored， and the results showed that the seed rooting was most beneficial at the temperature of 25. The study also explored the effects of different GA3 concentrations and treatment time on the germination of P. rockii. The results showed that when the concentration of GA3 was 300 mg/L and the treatment time was 24 h， the germination rate was the highest， reaching over 90%.
References
[1]JING XM， ZHENG GH， PEI YL， et al. A study on the relationship between seed germination of wild Paeonia rockii and P. szechuanica and their endangerment[J]. Biodiversity Science， 1995， 3（2）： 84-87. （in Chinese）
[2]FU LG， JIN JM. China Plant Red Data Book： Rare and Endangered Plants[M]. Beijing： Science Press， 1991. （in Chinese）
[3]CHENG FY， LI JJ， CHEN DZ， et al. Chinese Paeonia rockii[M]. Beijing： China Forestry Publishing House， 2005： 44-46. （in Chinese）
[4]CHENG FY， CHEN DZ. Studies on the selection and breeding of new hybrids from blotched tree peony （Paeonia rockii cvs.） and the cultivars classification of tree peony[J]. Journal of Beijing Forestry University， 1998， 20（2）： 27-32. （in Chinese）
[5]LIU X， LI CZ， TANG GG， et al. Germination characteristics of Paeonia rockii seeds[J]. Jiangsu Agricultural Sciences， 2016， 44（8）： 289-291. （in Chinese）
[6]ZHU XB， ZHAI WT， DONG XY， et al. Progress on chemical composition and function of peony seed oil[J]. China Oils and Fats， 2014， 39（1）： 88-90. （in Chinese）
[7]LI JJ. Chinese Paeonia suffruticosa Andr. and Paeonia lactiflora Pall.[M]. Beijing： China Forestry Publishing House， 1999： 1-2. （in Chinese）
[8]ZENG DX， YIN WL， ZHAO YQ， et al. Paeonia suffruticosa Andr. propagation technology[J]. Journal of Beijing Forestry University， 2000， 22 （3）： 90-95. （in Chinese）
[9]ZHENG XM， ZHOU YB， GU LP， et al. The properties of dormancy and germination of Paeonia suffruticosa[J]. Plant Physiology Journal， 1995， 31 （4）： 260-262. （in Chinese）
[10]CHENG FY， DU XJ. Effects of chilling and gibberellic acid on the seed germination and seedling growth in Paeonia ostii ‘Feng Dan’[J]. Acta Horticulturae Sinica， 2008， 35 （4）： 553-558. （in Chinese） [11]MA H， LI ZH， ZHANG YL， et al. Release of seed dormancy of Paeonia ludlowii[J]. Scientia Silvae Sinicae， 2012， 48（9）： 62-67. （in Chinese）
[12]LIU XX， ZHANG YL， MA H， et al. Studies on seed dormancy release of Paeonia delavayi[J]. Seed， 2013， 32（2）： 9-12. （in Chinese）
[13]LIN SM. Effect of different hormone and moistchilling on seed germination and seedling growth of Fengdan[D]. Nanjing： Nanjing Agricultural University， 2007. （in Chinese）
[14]QIAN XY. Physiological and metabolic changes in release of Fengdan seed dormancy by temperature and GA3[D]. Nanjing： Nanjing Agricultural University， 2009. （in Chinese）
[15]GAO SP， FAN BY， LIU GX， et al. Primary study on effect of epicotyls dormancy breaking of seeds of herbaceous peony and tree peony[J]. Northern Horticulture， 2008， 18805： 116-118. （in Chinese）
[16]FAN BY， GAO SP， SHI GA， et al. Study on the epicotyl dormancy breaking of seeds of peony （Paeonia suffruticosa Andr.） with GA3 and low temperature[J]. Seed， 2007（03）： 1-3. （in Chinese）
[17]CHEN HL， YANG YL， ZHANG XY， et al. Research progress on Paeonia suffruticosa Andr[J]. Hubei Forestry Science and Technology， 2013， 42（5）： 41-44. （in Chinese）
[18]GUO LP. Study on seed dormancy and dormancy release method[D]. Yangling： North West Agriculture and Forestry University， 2016. （in Chinese）
[19]ZHOU RC， YAO CH， PAN J， et al. Studies on characteristics of dormancy and germination of Paeonia rockii[J]. Hubei Agricultural Sciences， 2002（01）： 59-60. （in Chinese）
[20]JIN XM， ZHENG GH， PEI YL， et al. A study on the relationship between seed germination of wild Paeonia rockii and P. szechuanica and their endangerment[J]. Biodiversity Science， 1995， 3（2）： 84-87. （in Chinese）
[21]REN HY. Experimental study on seed germination and container seedling cultivation of Paeonia suffruticosa Andr[D]. Beijing： Beijing Forestry University， 2016. （in Chinese）
[22]ZHOU RC， YAO CH， PAN J， et al. Preliminary study on dormancy and germination characteristics of Paeonia rockii seeds[J]. Hubei Agricultural Sciences， 2002， 30（1）： 59-60. （in Chinese）
[23]YU L， ZHONG Y， WANG R， et al. Effects of gibberellic acid and chilling treatments on seed germination and seedling growth of Paeonia rockii hybrids[J]. Journal of Beijing Forestry University， 2015， 37（4）： 120-126. （in Chinese）
[24]LOU FF， ZHAO LS， LI ZY. Preliminary study on seed dormancy and germination characteristics of Paeonia lutea wild population on West Mount， Kunming[J]. Journal of Southwest Forestry College， 2007， 05： 34-37. （in Chinese）