Identification And Application Of Heat Resistance And Cold Resistance Of Three Strains Of Chaenomeles Speciosa

Chaenomeles speciosa(Sweet)Nakai is deciduous shrub and is usually used for landscaping and ornamental plants.High temperature in summer and low temperature in winter affect the growth and ornamental value,which are important factors restricting the introduction of ornamental plants.Three strains of Chaenomeles speciosa(‘2',‘T2',and ‘R')were used as test material,the semi-lethal temperature was assessed by electrolyte leakage method,and ATPase activity,5'-AMPase activity,soluble sugar and starch content,soluble protein content,and water content were measured during heat resistant period(from May to September)and frost hardening(from September to January).The result of heat-resistance and cold-resistance by comprehensive assessment method will provide the basis theory for enriching landscape tree species and application in the further.The main results are as follows:1.During the heat resistant period,the heat resistance of the three strains increased with the enhanced temperature,and the highest semi-lethal temperature was found in July and August.The semi-lethal temperatures of strain ‘2',strain ‘T2' and strain ‘R' were 49.98 °C,48.21 °C,and 45.42 °C,respectively.The heat resistance of three strains was assessed by comprehensive method with the parameters of soluble sugar and starch content,soluble protein content,and proline content.The results showed that the heat resistance of strain ‘2' was the strongest in three strains,strain ‘R' was the second and the strain ‘T2' was the weakest.2.During the frost hardening,the cold resistance of three strains increased with the decreased natural temperature,and the strongest cold resistance was found in November.The semi-lethal temperatures of strain ‘2',strain ‘T2' and strain ‘R' were-33.80 °C,-33.25 °C,and-27.42 °C,respectively.The cold resistance of three strains assessed by comprehensive method indicated that the cold resistance of strain ‘T2' was the strongest and the cold resistance of strain ‘2' was the weakest.3.The results of the comprehensive evaluation showed that strain ‘2' had the strongest heat resistance and the weakest cold resistance,which was suitable for high temperature regions in summer,while strain ‘T2' had the strongest cold resistance and the weakest heat resistance,which was suitable for cold areas in winter.4.With the decreased natural temperature,the ATPase activity and 5'-AMPase activity increased.According to the index coefficient,contribution rate and weight,the ATPase activity and 5'-AMPase activity might be used as indicators for cold resistance.