| Larix olgensis is one of the major barren hills afforestation tree species in northeastern China,because of the fast growth,strong adaptability,excellent wood properties and extensive uses,it has important economic and ecological status now.Therefore,conducting the research on genetic improvement of L.olgensis,which will contribute to accelerate the entire progress of improved varieties and enhance the benefits of economy and forestry ecology.Because the early clone propagation of larch was difficult,and superior families evaluation was the important way of breeding,lots of larch seed orchards were constructed in the 1960 s.However,compared to world research,the forestry seed orchards in our country were established late and the forestry tree improve work moved slowly.What's more,the early selection of excellent trees in seed orchard just only payed attention to the choice of a single trait and ignored the regular laws of flowering and fructification,seed sowing qualities,performance of progeny and some potential excellent features,which led to low overall genetic gain of current L.olgensis seed orchard in our country and there also existed unstable seed yield,low seed genetic quality and other problems,resulting in lower excellent variety afforestation rate.So in our study,with the parents clones and half-sib family progeny of L.olgensis seed orchard as experimental materials,carrying out the genetic variation researches on growth traits,wood properties,cold resistance,seed cone traits,germination characteristics and the growth traits of progeny,respectively,then we got the following results:(1)With 58 L.olgensis parents clones as materials,conducting the variation analysis of all growth traits and the result showed that there existed significant or extremely significant difference(P<0.05 or P<0.01)in different growth traits,the phenotypic variation coefficients ranged from 8.05-54.97%,which indicated there existed larger variation and was conductive to excellent clones selection.The repeatabilities of all growth traits ranged from 0.1023-0.7442,the repeatabilities of most of traits were larger than 04090,which belonged to middle or higher level repeatability,and the repeatability of tree height(H)was largest.All growth traits were divided into four principle components with principle component analysis,the four principle component values of different clones were different,which could provided basis for excellent parent clones selection.Finally,with 10% selection rate and growth traits as evaluation index,using the Brykin comprehensive evaluation method to conduct comprehensive evaluation,clones L59,L56,L77,L90,L92 and L87 were selected as excellent clones,the genetic gain of H,DBH and V were 15.43%,8.25% and 29.73%,respectively,which could be the selection materials of excellent parents in seed orchard.(2)Carrying out the genetic variation analysis of the wood properties of 58 L.Olgensisparents clones,the result suggested that there existed extremely significant difference in different wood properties of all clones,the phenotypic variation coefficients ranged from14.71-32.71%,the repeatabilities of all wood properties ranged from 0.2424-0.9355,which showed that there existed relatively abundant variation and was beneficial to the excellent wood properties parent clones selection.The correlation coefficient among different wood properties were different and there existed weaker correlation between growth traits and wood properties.With 10% selection rate and using the Brykin comprehensive evaluation method,while used wood properties to select,clones L59,L52?L36,L24,L97 and L62 were selected as excellent clones,the genetic gain of H,DBH,V,lignin content(absolute value),fiber content,fiber length and fiber width were 1.98%,18.65%,8.44%,7.48%,3.69%,6.18%,5.04% and 2.27%,respectively,which could be the selection materials of excellent pulp papermaking clones;while combining the growth traits and wood properties to select,clones L59,L91,L77,L90,L64 and L92 were selected as excellent clones,the genetic gain of H,DBH,volume,lignin content(absolute value),fiber content,fiber length and fiber width were15.14%,8.93%,30.86%,14.58%,4.82%,1.62% and 3.17%,respectively.(3)With current twigs of 58 parent clones as experimental materials and the treatment of low temperature stress,and with four clones of them under the conditions of different low temperature and stress time,then the result showed that there existed extremely significance in the relative electrolyte leakage rate of different clones under low temperature stress(P<0.01),and the electrolyte leakage rate of different parents clones twigs were changed differently under different low temperature stress.what's more,with the extension of low temperature stress and stress time,the electrolyte leakage rate of different parents clones were also different.With the electrolyte leakage rate difference values of-40?,12 h and control as clustering index to conduct system clustering analysis,clones L5,L16,L21,L23,L27,L40,L73,L78 and L90 were clustered together and selected as the stronger cold resistance clones preliminarily,which could be selected as excellent cold resistance clones breeding materials and thus providing basis for resistance breeding and comprehensive evaluation selection of excellent clones.(4)With the seeds of 21 parents clones as materials and investigation of the seed cone traits and seed germination characteristics,the results showed that the difference of seed cone traits and seed germination characteristics among different families were extremely significant(P<0.01),phenotypic variation coefficients of all characters ranged from 13.34-69.47%,repeatabilities of different traits ranged from 0.7757-0.9463,which belonged to high repeatabilities level,and there also existed a certain degree correlation between seed cone traits and germination characteristics according to correlation analysis,which benefit to the excellent genetic sowing quality seed selection.Finally,with seed germination rate,germinationpotential and germination index as clustering target,clone L17,L40,L49,L52,L55,L67,L71,L88 and L99 were clustered together and had the good performance of germination characteristics,which could be the selection materials for excellent qualities seed and provided the theoretical basis for excellent seed breeding and the comprehensive evaluation of excellent families or clones selection.(5)Carrying out the continuous progeny test and genetic variation study on the tree height and diameter at breast height of 60 different half-sib families for many years,results showed that there existed extremely significant difference(P<0.01)in H and DBH among different families at different ages,phenotypic variation coefficients of H and DBH in all years ranged from 17.83-33.01% and the heritabilities ranged from 0.487-0.798,abundant variation and higher heritability level were conductive to the excellent families selection.Age-age correlation analysis indicated that there existed significantly positive correlation coefficients among different traits in different years,the correlation coefficients between different traits show some different variance with years changed.While the selection rate reduced with ages,different families were selected in different years,family L30,L48,L58,L64 and L101 were always selected and performed well.Finally,family L30,L38,L48,L58,L64 and L101 were selected as excellent families under 10% selection,the genetic gain of H and DBH were 7.13%and 8.40%,respectively.18 excellent signal plants: L64(104),L58(125),L38(39),L101(584),L30(41),L58(127),L101(81),L101(15),L48(517),L101(581),L58(163),L64(187),L48(33),L48(35),L48(64),L58(1428),L38(1196)and L38(59),which were selected from above excellent families and the genetic gain of H and DBH were 16.95% and19.64%,respectively.The selected excellent families and individual plants could be used as the establishment materials of improved and second generation seed orchard and provided the fundamental basis for the selection and evaluation of excellent families or clones.In short,we had a good knowledge of variation analysis of growth traits,wood properties,cold resistance,seed cone traits,germination characteristics and growth traits of progeny of L.Olgensis parents clones,which could provide theoretical foundations for the comprehensive and accurate evaluation and selection of excellent families or clones in L.Olgensis seed orchard,and also provide a reference for seed orchard upgrading. |
PDF Full Text Request