Genetic Diversity Of A Larix Olgensis Henry Seed Orchard Using SSR Markers

To find out the changes of genetic diversity in the Larix olgensis Henry elementary clone seed orchard,we take the38clones (260individuaLS) in Qingshan Weihe L. olgensis orchard and21half-sib progenies(146individuaLS) as the materiaLS and use14pairs SSR primers to analyse the genetic diversity.By conventional methods, we anaylyse the diversity both seeds growth of21family and the growth of25half-sib progenies.Using SSR markers,Genetic diversity in a Larix olgensis Henry seed orchard before and after thinning were analysed.The following were results:(1) Parentage population and the progeny population showed a high genetic diversity.the average effective number of alleles of parentage population and the progeny population respectively are4.0714,4.9286.Shannon’s diversity(1.0232) index,mean expected heterozygosity(0.5493),the Nei diversity(0.5475) all higher than the parentage’s(0.9805、0.5146、0.5136),except that the effective number of alleles(2.3163) lower than the parentage’s(2.3258).Compared with the parent groups genetic diversity, the parent and offspring groups have19.72%,10.84%heritable variation value respectively; The gene flow value(Nm*) of parent and offspring is1.0179,2.0572(more than one) respectively. From the persective of the parent clone of Larix olgensis seed orchard and the off spring family groups, the SSR genetic diversity between the differnet clones in the offerspring groups has no significant difference with that in the parent groups.(2) there were extremely signifieant differences for1000-grain weight,water content,Seed Fineness Test,empty grains,astringent grains,germination percentage test and germination energy test.Seed soundness has a highly significant positive relationship with the water content, thousand seed weight and germination percentage. Whereas, it has a highly significant negative relationship with the percentage of empty grains and dry grains. The water content has a highly significant positive correlation with the thousand seed weight,and,germination potential and a negative correlation with the percentage of empty grains.Thousand seed weight has a significant positive relationship with both germanation percentage and germination potential, moreover, germination percentage has positive relationship with the gernimation potential, and percentage of empty grains has close positive correlation with the percentage of dry grains. there were extremely signifieant differences for DBH and height of half-sib progenies,DBH(diameter at breast height) does not have significant difference with the volume of wood,(variable coefficient, etc), both tree height and DBH have very significantly positive correlation with the volume of wood.(3) According to the individua LS’ability of growth, bearing and their progeny, we design simulation thinning of the intensity from10to60%, and analyze the changes of genetic diversity before and after thinning by POPGENE3.2.The results show that the reduction level of genetic diversity is positive correlation with the thinning intensity,it less affected if the thinning intensity is less than40(reduction is less than0.5%).If the genetic diversity of one clone is preserved, at least7-9individuaLS need to be reserved, so it would not be affected of the orchard genetic diversity if each clone needs to consist of more than12～15individuaLS at the beginning of building a Larix olgensis orchard by the preservation rate is60%after thinning.