Research On The Introduction And Domestication And Ornamental Appraisal For Crape Myrtle Cultivars Form America

Common crape myrtle(Lagerstroemia indica L),which belonged to Lagerstroemia,is deciduous shrubs or trees.‘Red Rocket',‘Pink Velour',‘Dynamite',‘Ebony Fire',‘Ebony Embers',‘Ebony Glow' and ‘Ebony Ivory' were an excellent cultivars of Crape myrtle series introduced from the United States by Hunan academy of forestry sciences.Among them,‘Red Rocket',‘Pink Velour' and ‘Dynamite' had the advantages of bright color,long flowering period,cold tolerance,drought tolerance and strong adaptability.‘Ebony Fire',‘Ebony Embers',‘Ebony Glow' and‘Ebony Ivory' are new varieties of crape myrtle with ornamental of flowers and leaves.With the continuous improvement of people's living quality and standard,landscaping and ecological environment construction have been becoming the new pursuit.The introduction and domestication experiment of crape myrtle cultivars form American in Chongzhou was carried out.The phenological period,growth characteristics,flowering-related traits,leaf traits,arboricultural pruning,and ecological adaptability of the local crape myrtle cultivars were compared,and the introduction adaptability were comprehensively evaluated by principal component analysis(PCA).The analytic hierarchy process(AHP)was constructed to comprehensively evaluate the ornamental value of different crape myrtle cultivars in this paper.Through the above experiments,the selection of crape myrtle cultivars with strong adaptability,high ornamental value and high commercial value were screened to enrich the varieties of flowers and seedlings in Sichuan.The main research contents were as follows:(1)The climate similarity theory,ecological history analysis,Michurinism,distribution of resources and ecological suitability were analyzed,which indicated that the introduction of crape myrtle cultivars was feasible.The differences of natural conditions in the areas of origin,cultivation and introduction of crape myrtle cultivars in the United States were compared and analyzed,it was founded that rainfall might be the limiting factor for the introduction of crape myrtle cultivars.(2)The biological characteristics of different crape myrtle cultivars were studied.Mid-march entered sprouted phase.Sprout leaves period was completed in early April.Mid to late June to early July was the beginning flowering stage.Late August came into full-bloom stage and visible parts of the fruit,to the end of mid to late September was the late flowering.In October,the leaves of crape myrtle began to change color and the fruit gradually matured.In mid-november,the leaves were almost completely detached,and part of the capsules turned from green to greyish-black to split,persistent on the plant.The growth curve of the the length of branches growing each crape myrtle cultivars presented "S" type change.The differences in growth,flowering and leaf traits of all crape myrtle cultivars reached the extremely significant level(P < 0.01).The effects of pruning on the growth of the main stem diameter of‘Red Rocket',‘Pink Velour' and ‘Dynamite' all reached the extremely significant level(P < 0.01).A moderate amount of pruning could effectively increase the growth of the main stem diameter of crape myrtle.(3)The research on the ecological adaptability of different crape myrtle cultivarswere studied,the high-temperature adaptability was ranked as ‘Pink Velour' > ‘Ebony Ivory' > ‘Red Rocket' > ‘Ebony Fire' = ‘Ebony Glow' > ‘Ebony Embers' >‘Dynamite' > ‘Wenjianghonghua'(CK).The low temperature adaptability sequence was ‘Ebony Fire'> ‘Ebony Ivory' > ‘Red Rocket' = ‘Ebony Glow' > ‘Ebony Embers' > ‘Pink Velour' > ‘Wenjianghonghua'(CK).The order of pest resistance was‘Ebony Glow' > ‘Ebony Embers' > ‘Ebony Fire' > ‘Ebony Ivory' > ‘Dynamite' >‘Red Rocket' > ‘Pink Velour' > ‘Wenjianghonghua'(CK).The order of ecological adaptability was ‘Ebony Glow' = ‘Ebony Fire' = ‘Ebony Ivory' > ‘Ebony Embers' >‘Red Rocket' > ‘Dynamite' > ‘Pink Velour' > ‘Wenjianghonghua'(CK).(4)The correlation analysis was used to screen the traits of crape myrtle.The 17 traits were screened for principal component analysis,and the cumulative contribution rate of the first 4 principal components was extracted to 92.6008%.The comprehensive score sequence of different characters of crape myrtle cultivars was‘Dynamite' > ‘Red Rocket' > ‘Pink Velour' > ‘Ebony Embers' > ‘Ebony Fire' >‘Ebony Glow' > ‘Ebony Ivory' > ‘Wenjianghonghua'(CK).Among them,‘Dynamite'and ‘Red Rocket' had strong adaptability and can be promoted and developed in introduced areas.(5)The ornamental value of crape myrtle cultivars was comprehensively evaluated by the analytic hierarchy process(AHP).The weight values of each index in the constraint layer(C)of the evaluation system were ranked as follows: Flower(C3)> Leaf(C4)> Plant habit(C1)> Branche(C2).The order of weight values of each index was from high to low: P7 > P10 > P14 > P9 > P12 > P3 > P11 > P4 >P15 > P16 > P6 > P1 > P8 > P13 > P5 > P2.The weight value of flower color(P7)was the largest,and it was the first reference index to evaluate the ornamental value of crape myrtle cultivars.In addition,the number of flowering branches,the color of leaves,the size of inflorescence,the number of inflorescences and the length of florescence had a great influence on the ornamental evaluation.According to the comprehensive evaluation value,the order was ‘Red Rocket' > ‘Dynamite' > ‘Ebony Fire' > ‘Pink Velour' > ‘Ebony Embers' > ‘Ebony Glow' > ‘Ebony Ivory' >‘Wenjianghonghua'(CK).The ‘Red Rocket',‘Dynamite',‘Pink Velour',‘Ebony Fire',‘Ebony Embers' evaluation level for the first ?level,high ornamental value;The first? grades of cultivars were ‘Ebony Glow' and ‘Ebony Ivory';‘Wenjianghonghua'(CK)was the first ? level.