| In order to screen high-quality,high-yield,and strong cold resistance types of F.suspensa,and explore the physiological and ecological adaptability of F.suspensa from different regions in the Shijiazhuang mountainous area,the growth characteristics,yield,fruit quality,photosynthetic characteristics,and changes in physiological indicators of different organs of F.suspensa from Yuncheng,Shanxi,Sanmenxia,Henan,and Shijiazhuang,Hebei were observed and studied using the membership function method for cold resistance evaluation,The main results are as follows:(1)The tree shapes of Shanxi and Henan Forsythia are relatively upright,making it easy for manual management.The average yield per plant of Shanxi Forsythia is 0.41 kg,significantly higher than that of Henan Forsythia(0.32 kg)and Hebei Forsythia(0.25 kg).There was no significant difference in the content of forsythia glycoside and forsythia ester glycoside A among the three types of F.suspensa.The content of forsythia glycoside was between 0.82%and 0.93%,and the content of forsythia ester glycoside A was between 7.17%and 7.68%.The volatile oil content of Shanxi F.suspensa and Henan F.suspensa were 2.1 1%and 2.05%,respectively,while that of Hebei F.suspensa was 1.64%.(2)Shanxi F.suspensa has a larger leaf area,the highest chlorophyll content,lower light saturation and compensation points,and the lowest maximum net photosynthetic rate of 7.49 μmol·m-2·s-1,with strong ability to utilize weak light,is suitable for planting on semi shaded slopes or open spaces under forests in mountainous areas.Henan F.suspensa has a large leaf area,deep leaf color,low chlorophyll content,high light saturation point and light compensation point,and a maximum net photosynthetic rate of 10.54 μmol·m-2·s1,with a higher net photosynthetic rate under strong light,needs to be planted on a well lit site.Hebei F.suspensa has a small leaf area,deep leaf color,and low chlorophyll content,but its chlorophyll a/b value is the highest,with low light compensation points and high light saturation points.It can adapt to a wide range of light,with a maximum net photosynthetic rate of 13.23 μmol·m-2·s-1,significantly higher than the other two types of F.suspensa,has strong photosynthetic ability under different lighting environments.(3)After being subjected to low temperature stress,the trend of SOD activity in three types of F.suspensa decreased first and then increased with the decrease of temperature,while the trend of POD and CAT activity increased first and then decreased.These three antioxidant enzymes work together to eliminate excess reactive oxygen species in F.suspensa,and their activity is positively correlated with the cold resistance of F.suspensa.After being subjected to low temperature stress,the three types of F.suspensa will rapidly increase the content of soluble proteins and soluble sugars in their bodies.Although the trend of changes with decreasing temperature is different,the higher the overall content,the stronger the cold resistance ability.The proline content in the branches and petals of three types of F.suspensa is strongly correlated with cold resistance,but the relationship with young fruits cannot be determined.The starch content in F.suspensa is not correlated with soluble sugar content.Therefore,under low temperature stress,the starch in F.suspensa will not be converted into soluble sugar.(4)The calculation results of the semi lethal temperature of three different organs of F.suspensa are as follows:the range of the semi lethal temperature of branches is-32.44～29.26℃,the range of petals is-6.72～-5.93℃,and the range of young fuits is-3.78～3.09℃.A comprehensive evaluation was conducted on the cold resistance of three different organs of F.suspensa.The results showed that the branches and young fruits of Henan F.suspensa had the strongest cold resistance,while the petals of Shanxi F.suspensa had the strongest overall cold resistance.However,when the temperature was too low,the cold resistance of the petals was weaker than that of Henan F.suspensa and Hebei F.suspensa.The branches,petals,and young fruits of Hebei F.suspensa had the lowest comprehensive cold resistance. |
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