| Larix olgensis is one of the most important timber species in Northeast China.It is not only used in barren hills for afforestation,but also used as building materials and papermaking materials.It has a fast growth rate,strong adaptability,excellent wood properties,a wide range of uses,and has important economic and ecological status.Research on genetic improvement of L.olgensis will help speed up the process of breeding and improve economic and forest ecological benefits.Because the expansion of early deciduous clones is difficult,the evaluation of excellent families is the main way of breeding good varieties.Therefore,in the 1960s,a large number of larch seed orchards were established.Late,the improvement of forest trees progressed slowly,and early seed orchard evaluation only focused on parental growth traits,neglecting its flowering and fruiting rules,seed sowing quality and other characteristics,which led to the current two types of seed yield instability of L.olgensis seed orchard in China.Problems such as low genetic quality have led to lower utilization rates of improved varieties.In this study,the parents and progeny of L.olgensis seed orchard were used as test materials.The genetic variation of the growth traits and wood traits of the parental clones was studied.The genetic variability of the growth traits,wood traits,cold resistance and progeny growth of the progeny families The following research results were obtained:(1)With 49 L.olgensis parents clones as material,conducting the variation analysis of all growth traits showed that there were extremely significant differences between each growth trait(P<0.01),and the phenotypic coefficient range from 7.71%～31.93%,there is a large variation,which is conducive to the selection of excellent clones.The repetitive force of each growth trait ranged from 0.44 to 0.76,of which the volume repetitive force was the largest,and the repetitive power of each growth trait was above 0.44,which belonged to the medium and high repetitive power level.Principal component analysis was used to divide the growth traits into two principal components.The principal component values of different clones were different,which provided a basis for the selection of excellent parent clones.Based on the results of the principal component analysis,the comprehensive evaluation of multiple traits was performed using the growth traits of the parental clones as indicators,and selection was made at a 10%inclusion rate,clones L76,L5,L7,L12 and L4 were selected as excellent parental clones.The genetic gains of tree height(H),ground diameter(GD),diameter of breast height(DBH),diameter of stem at 3 meter height(D3),and volume(V)were 3.55%,4.72%,6.14%,6.93%,and 15.50%,respectively,and could be used as selection materials for excellent parental clones in seed orchards.(2)Variation analysis of the growth traits of 49 L.olgensis progeny families showed that the differences between the growth traits of each family reached a significant level(P<0.01),and the phenotypic variation coefficient of each trait ranged from 3.04%to 23.15%,There is a certain degree of source of variation among various traits,which is conducive to the selection of excellent families.The heritability of each growth trait was more than 0.5,which belonged to the middle and high repetitive levels,indicating that each trait has a stronger ability to inherit to offspring.Principal component analysis was used to divide each growth trait into three principal components.Based on the results of the principal component analysis,the multi-trait comprehensive evaluation was performed using the offspring family growth traits as indicators,and the selection rate was 10%.The families S78,S81,S80,S84 and S83 were selected as excellent offspring families.The genetic heights of H,GD,DBH,D3,and V of the selected families were 2.24%,6.53%,3.39%,7.71%,and 7.71%,it can provide materials for the production and application of L.olgensis.Using the same growth traits to analyze the correlation between the parental clones and the offspring families,the analysis results show that there is basically no significant(P<0.01)or significant(P<0.05)situation between the growth traits of the parents and the growth traits of the offspring,indicating that the superior clones of their parents may not necessarily be superior.(3)Genetic variation analysis of the wood traits of 49 parental clones and progeny families showed that there were extremely significant differences in the wood traits of the parental and progeny(P<0.01),and the variation range of the coefficient of variation of the woody traits of the parental clones ranges from 11.24%-18.18%.The coefficient of variation of the wood traits of progeny families ranges from 7.64%to 15.30%.The repetitive power of each trait of the parental clones is greater than 0.9,which is a higher level of repetitive power.The heritability of the wood density of the progeny family is 0.59 It belongs to the medium and high heritability level.The heritability of the wood fiber length and width of the progeny families are both 0.95.It belongs to the higher heritability level.The differences between the various wood traits are large,which is conducive to the selection of excellent wood trait parents and offspring.Correlation analysis was performed on the wood traits of parental clones and progeny families.Except for the significant positive correlation between parental fiber length and parental fiber width,progeny fiber length and progeny fiber width(P<0.01),other traits Correlation presents a smaller positive correlation or a smaller negative correlation.With a selection rate of 10%,using the Bragging Comprehensive Evaluation Method,and selecting wood properties as comprehensive indicators,clones L84,L6,L58,L76 and L38 were selected,and families S13,S15,S74,S16,and S5 were selected.The same line number,this result is consistent with the correlation result,which once again shows that the parental clone of a good parent is not necessarily good.At the same time,the correlation analysis between the growth traits and the wood traits of the parents showed that there was a weak correlation between the wood traits and the growth traits.Therefore,the selection should be based on the breeding goals when selecting breeding.(4)Using 49 offspring families as materials,cold resistance test was performed on them,and 4 families were treated with low temperature stress at different temperature and time.The relative conductivities of the four families were significantly different.Based on the difference between the electrical conductivity and the control of each family under the treatment at-40℃ for 12h,the system cluster analysis was used to preliminarily screen offspring families with strong cold resistance:S51,S74 and S1,which could be excellent The comprehensive evaluation selection of the pedigree provides the basis.(5)Variation analysis of H and DBH at different ages of the 49 L.olgensis progeny families.The differences in H and DBH of each family in different years were extremely significant(P<0.01).The phenotypic variation coefficient of H ranges from 6.95%to 30.22%,and the phenotypic variation coefficient of DBH ranges from 7.93%to 33.74%.The heritability of H and DBH of families of different tree ages is greater than 0.7.The coefficient of variation and higher heritability levels are conducive to the selection of excellent families.The correlation results showed that there was a very significant positive correlation between H and DBH at different ages(P<0.01),indicating the feasibility of early selection.Using the Brecken’s multiple traits comprehensive evaluation method,with a 20%enrollment rate,the families selected in 18a have been selected in the years selected later,so the age of the best early selection is 8 to 18 years,which shortens the long white leaves Pine breeding process.According to the different selection rates in different years and according to the size of Qi value,the families S78,S81,S80,S84,and S82 were selected as excellent families.The genetic gain of H and DBH was 2.26%and 3.39%,respectively.Provide materials for improvement and construction of second-generation seed orchards.In summary,this study carried out variation analysis on the growth traits and wood traits of the parental clones of L.olgensis.Variation analysis of growth traits,wood traits,cold resistance and progeny growth of Larix olgensis progeny families provides a basis for comprehensive evaluation and selection of excellent clones and families of L.olgensis seed orchards,and also provides a reference for upgrading or replacement of seed orchards. |
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