| Clematis a new type of vine greening plant with high ornamental value which is origin in the temperate zone.However,many ornamental clematis have not been fully utilized in landscaping due to the hot summer in most areas of China.Therefore,it is great value to carry out research on the heat resistance and breeding Clematis for the application of Clematis in gardens.Firstly,this study observed the changes of plant heat damage under high temperature stress,and measured the changes of physiological indexes before and after stress,leaf structure and stomatal characteristics of 10 Clematis varieties mainly planted in China.Correlation analysis,principal component analysis and membership function method were used to comprehensively evaluate the heat resistance of the above 18 indexes.Thus,the indicators related to the heat resistance of Clematis were preliminarily determined,and the Clematis varieties with strong heat resistance were selected for crossbreeding experiment.Secondly,the hybrid parents were selected by observing the flowering dynamics of Clematis,and their pollen vigor and stigma availability were used to determine the optimal pollination time,which provided the basis for the hybridization experiment of Clematis.Finally,the rapid propagation of the heat-resistant Clematis ‘Avant Garde Evipo033’ was studied to lay the foundation for the breeding of Clematis.The following research results were obtained:(1)The heat resistance of 10 Clematis was analyzed by heat resistance evaluation.the results from strong to weak were: C.‘Blue light’ > C.‘BIJou Evipo030’ > C.‘Utopia’ >C.‘Juuli’ >C.‘Avant Garde Evipo033’ > ‘Green magnetism’ >C.‘Roguchi’ > ‘Purple melody’ >‘Bode’ >‘Red martin bells’.Five indicators of CAT,Pro,leaf thickness,spongy tissue and stomatal density can be preliminarily screened out as the basis for evaluating the heat resistance of Clematis.and three heat-resistant varieties including C.‘Blue light’ 、 C.‘BIJou Evipo030’ and C.‘Utopia’ were selected,which could be used for new variety breeding and landscaping application in South China.(2)Five Clematis with high heat resistance and high ornamental value,C.‘Utopia’、C.‘Junli’、‘Green magnetism’、‘Bode’and ‘Purple melody’,were selected for crossbreeding,and 449 fruits were obtained.Among them,the number of hybrid fruits was 259,and the number of self-crossed fruits was 190.the pollen viability of these five Clematis cultivars was above 86 % on the second day of loose pollination,and their stigma receptivity was sustainable 4 days.The stigma has the strongest receptivity in 1-2 days after flowering,During this period,there are more bubbles in the stigma,At this time,there are more bubbles in the stigma,and the more oxidized the stigma,the darker the color.Therefore,the best period for artificial pollination of Clematis is 1-2 days after flowering.(3)The results showed that the axillary buds could be induced by different concentrations of plant hormones(1 mg/L 6-BA and0.25～1 mg/L TDZ)in the primary culture,and the advanced-bud induction rate reached 100 %.Through two factors and three levels of complete test,the bud proliferation was the highest in MS+1mg/L6-BA+ 0.5 mg /L TDZ medium,and the proliferation coefficient was up to 5.27.The optimal rooting medium was 1/2 WPM+0.05 mg/L NAA+0.2 mg/L IBA,the rooting rate was 84.44 %,and the survival rate was 48 % in natural environment. |
PDF Full Text Request