Study On Wind Resistance Characteristics And Association Analysis Of Important Traits In Eucalyptus Camaldulensis

Frequent typhoons in summer caused a major threat of trees in coastal area of south China,Wind damage had become one of the important restricted factors for sustainable development of Eucalyptus plantation,and had seriously affected the development of ecological security and related industries in coastal areas,so it was necessary to select windresistant species(clones)for the construction of commercial forests and coastal protection forests.Breeding excellent wind resistant strains of eucalyptus is one of the important conditions to ensure the sustainable development of commercial Eucalypt plantations in coastal areas of China.Eucalyptus camaldulensis as a kind of qualified hardwoods with drought-resistance,barren-tolerance,wind-resistance and strong disease resistance,is an important genetic material of eucalyptus species for improvement.In this paper,based on a follow-up research on the 26 traits of 114 E.camaldulensis families(half-sib)about the growth,wood properties,physical mechanical properties and chemical components and so on.,genetic variation analysis and correlation analysis of each trait were carried out to find the main factors influencing wind-resistant of eucalyptus,then the main factors affecting the deformation and wind resistance under wind load and heavy load were analyzed by a wind damage simulation method using to draw tree experiment),and wind resistance of E.camaldulensis families were evaluated.Finally the influencing factors of wind resistance were obtained and the excellent wind-resistant E.camaldulensis families were selected.Wind resistance of Eucalyptus was caused by many complex factors.In this study in term of on the main influencing correlation factors on the wind resistance of E.camaldulensis,SSR association analysis of molecular markers were used to analysis the genetic base and find excellent alleles of wind resistance in E.camaldulensis.This study will be helpful to establish molecular markers assisted selection system for wind resistance of Eucalyptus,and the results will provide a theoretical basis for further research.The main results were showed as follows:1.There was abundant genetic variation among the growth traits of the E.camaldulensis family,and the family heritability of each trait was higher than the individual heritability.E.camaldulensis showed a lack of correlation between wind resistance and tree size in the early period(1 year old).There were abundant genetic variation among the traits,which had strong potential for individual selection in families and single plant.Correlation coefficients among H,D,V and CD were very high,which were higher than 0.5(P> 0.01).The highest correlation coefficients of WD and V were 0.414,and the regression equation showed that the correlationship of wind resistance and growth traits was not significant?Research on wind resistance of 2~3 years E.camaldulensis showed that the average wind damage index was 2,the wind damage index and forest tree size(height,individual volume)had a strong negative correlation between families.The wind resistance had difference and hereditary,and the genetic control level of some traits was relatively high.Wind damage of 3~4 year old E.camaldulensis families was significantly negatively correlated with tree height,crown width,volume and thickness of the bark,that is,the stand was higher and had a greater the volume,and its wind resistance was stronger.The research showed that wind resistance of E.camaldulensis were related with tree height,DBH and volume.2.The results showed that there were no significant difference among different families,family parts and their family and parts.The density of 40 month E.camaldulensis was minor,which is light wood.The air dried(tangential and radial)and over dried(radial and tangential)shrinkage difference was very significant.E.camaldulensis shrinkage was III level,easy to crack.The dry shrinkage value of base of the trunk was higer than the middle and top part,which more prone to cracking and deformation.The mechanical properties difference of E.camaldulensis between families(bending strength,elastic modulus,longitudinal shear strength,compressive strength)were significant,and bending elastic modulus significantly,other indexes had no significant differences among different parts.The study found that the main factors affecting the wind resistance of Eucalyptus were the size of trees(tree height,DBH,volume),followed by wood properties.Wind damage degree of stand was closely related with its size,also had strong correlations with some wood properties such as fiber width,Pilodyn value,stress wave vaule.But it had not significant correlation with wood basic density,dry shrinkage,mechanical properties(bending strength,elastic modulus,shear strength,compressive strength,etc.)and wind resistance of E.camaldulensis.The correlation of wind damage index and lignin,holocellulose,alpha cellulose,hemicellulose were not significant(P>0.05).correlation analysis,the relationship among wind resistance of E.camaldulensis and physical mechanical properties and chemical components count for little.3.The regression analysis and canonical correlation analysis among three factors(the tension of the tension,tree trunk deformation degree and angle)were carried out to obtain the main factors through wind damage by a simulation method(tree-pulling experiment)and the 26 traits of the growth,wood properties,physical mechanical properties and chemical components,The results were showed that:tree height,DBH,volume,bark thickness,fiber length,dry shrinkage,tensile strength,tensile modulus and cellulose content were the main factors/traits affecting tree wind reisitance.The most important traits impact on wind-resistant were the growth characteristics of E.camaldulensis mainly including tree height,volume and DBH,followed by fiber length and tensile strength.4.The test material was 109 samples from the 8 populations of E.camaldulensis,and the reference marks were 107 SSR loci covering the whole genome.55 neutral genomic SSRs revealed high levels of population diversity in E.camaldulensis group,1116 alleles were detected and the average was 20.3 alleles.PIC ranged from 0.3508 to 0.9489 and average was 0.771 loci which were highly polymorphic loci.The average value of HE was 0.718 which indicating the high heterozygosity of E.camaldulensis.The average value of Fst is 0.066 which indicated that the genetic differentiation among populations was not significant.The molecular analysis of variance between groups variance components accounted for only 1%,indicating that the genetic variation mainly exists within the population.Based on the genetic distance analysis of Nei(1972),it was found that the genetic background of Australian sub populations was relatively large.The population of E.camaldulensis was rich in genetic diversity,and it can be used as a gene bank for breeding and genetic improvement.5.Based on more than 800 SSR markers covering the whole genome of E.camaldulensis for PCR optimization and screening of gene pool for 8 strong wind-resistant and 8 weak wind-resistant E.camaldulensis plants.Finally got 107 SSR markers that allelic frequency were quite different in the two types genetic pool for association analysis for wind-resistant relevant traits of E.camaldulensis.The 4 traits(tree height,diameter at breast height,volume and wind resistance index)were significantly linked with 26 SSRs(P<0.05)which could explain the 9.26%~71.14% phenotypic variation of growth and wind resistance traits for E.camaldulensis in 3-4 years.Among them,the tree height's related loci up to 13 was the highest,and the other traits 's related loci were 5~8.The lacus EUCeSSR235 had the highest interpretation rate(71.14%)and the lacus EUCeSSR570 had the lowest interpretation rate(9.26%)in the 26 association sites,and the average interpretation rate was 36.27%.It was substantially correlated between Locus EUCeSSR332 with tree height,diameter at breast height,volume,wind index,and the interpretation rate of phenotypic variance was more than 60%.The loci EUCeSSR484,EUCeSSR352,EUCeSSR570 and EUCeSSR422 were correlated with tree height and wind resistance index,and the loci EUCeSSR489 and EUCeSSR114 were related with tree height and volume.