Combined Selection Of Growth Traits And Seed Setting Traits Of Two Parents Of Larix Principis Rupprechtii

In this thesis,the progeny test forest and parents of Larix principis rupprechtii in Longtoushan national Larch improved variety base of Mulanweichang in Hebei Province were used as experimental materials.The growth of progeny forest,seed setting of parents and SSR molecular markers were mainly studied in order to screen the excellent hybrid combination with good growth performance and better seed setting of parents,The fingerprints of 20 selected plus trees were constructed to provide breeding materials for further improvement and upgrading of seed orchard.The results were as follows :1.There were significant differences in growth(TH,DBH,volume)and some trunk shape and quality traits(TS,BA)of Larix principis rupprechtii full sib progenies.Through the comprehensive evaluation of growth and trunk shape and quality,it was found that the volume changes greatly,while the overall score of trunk shape and quality was higher.Therefore,taking volume as the main index,under the32% selection intensity,a total of 12 hybrid combinations,44×205,43×205,205×120,77×98,55×205,77×205,53×205,53×53,53×77,59×120,43×120 and 49×77,were selected.Genetic gain of TH,DBH and volume in selected populations were 19.4%,17.6% and 63.9%.2.There was no significant difference in cone yield and seed yield between the parent clones of Larix principis rupprechtii full sib progeny test forest,but the parent clones had better seed setting,while other seed quality(1000 seed weight,plumpness rate,germination rate)had significant difference,indicating that the seed orchard had potential selection value.Combined with the seed yield and quality of parent clones,6 parent clones were selected,including 52,53,59,77,120 and 205.3.Combined with the growth of progeny forest and the seed setting of parents,five excellent hybrid combinations(205×120,53×205,53×53,53×77,59×120)were selected,and 20 plus trees were selected based on the breeding value of volume.4.There were the same parents in the 20 plus trees,so the fingerprints of these20 plus trees were constructed.Through genetic diversity analysis,it was found that the genetic diversity index and pic of these 20 plus trees were 0.320 and 0.240 respectively,which belonged to medium genetic diversity;heterozygosity was 0.640,and heterosis was obvious.