Study On Eight Kinds Of American Lagerstroemia's Introduction And Adaptability In Wuhan

Lagerstroemia indica,The alias'hundred days of red'?'itch trees'.Lythraceae Lagerstroemia deciduous shrub or small tree.Open during the summer,inflorescences cone,is important landscape trees and shrubs in summer.US crape myrtle flowers with its big,bright color,strong resistance characteristics attracted more and more attention in our garden construction.In this study,introduced eight American crape myrtle seed strains,from Sacramento,California,United States.For two consecutive years to compare their growth law,phenology,reproductive characteristics and resistance to future generations,etc.Analysis its Adaptability,Introduction material value evaluation by AHP.Preliminary screening for applications crape myrtle material in Wuhan.Related results are as follows:1.Growth and development of regularity InvestigationObserving that the US Lagerstroemia indica L.has normal growth and development regularity.Since early March into the infancy,until June is the initial stage of growth.each strain grow into the rapid growth phase on June,growth rate varying degrees of improvement,then in late August,early September into the slow growth period,until October of entering deciduous.The overall trend for each strains' side shoot growth is the spring shoots>summer shoot>autumn shoots,spring shoots,TGRP's Spring shoot growth reached a maximum of 31.17cm;As the summer flowering consume some nutrition,summer shoot growth is less than the majority of spring shoots,up to 17.77cm;Most strains' autumn shoot growth below 10cm,maximum strain is 2R,reachs 14.40cm.2.Phenology InvestigationThe survey found that between the US Lagerstroemia,Phenophase differs.Have begun to sprout since early March,Late March to early April has complete the expansion into the vegetative growth.Since the time of flowering the first year after planting,large differences between strains flowering,Since mid-June to early August,there have been strains began to blossom.Into October,leaves began to change color in late October appears deciduous phenomenon.TGR strains bud early,on March 1 began to germinate;the earliest flowering strains EHR,June 15 begins to bloom.Each strain flowering in groups ranging between 34-57d,and between the flowering plant 12-34d.Since the first year of growth and flowering,Fewer flowering plant,Not formed inflorescence,florescence flowering up to the majority are concentrated in the 20 to 35 flowers.3.Adaptability survey and Evaluation of introduction ValueThrough the introduction of Lagerstroemia cold resistance,heat resistance,pest resistance and sexual reproductive capacity survey,each strain can adapt to the climatic conditions in Wuhan.Cold hardiness investigation,the findings of overwintering in March 2015 showed Cold index in the strains except EHP,ARC,other are less than 1.5,indicating that all have a strong resistance to the cold;Survey in March 2016,In addition to a small amount of strain ARC plants have different degrees of victims,other victims of strain almost no symptoms,or very mild degree.Heat resistance investigations,2015 average temperature in summer is 34??extreme maximum temperature reached 36 ?,Through the survey found that the leaves and stems,there was no damage symptoms occur,prove that it can adapt to high temperatures in Wuhan.Pest-resistant aspects,disease occurred earlier than pests.In mid-April due to air humidity,there are 1-2 strains has signs of powdery mildew.In late April there are very few plant has occurred pest,damage was slight.Except EHR lines's sexual reproduction germination rate less than 50%,other lines were higher than 60%,highest rate is strain D3FR's,reached 90.33%.Each strain transplant survival rate above 90%,It shows that most strains of sexual reproduction ability,can adapt to the climatic conditions in Wuhan.By AHP,comprehensive comparative evaluation concluded that strains EHR,TGSR introduction highest value,followed by lines EHP?TGRP and 2R?TGR?D3FR?ARC.