Study On Seed Characters And Genetic Diversity Of Masson Pine Tungong Provenance

The reproductive capacity and mating dynamics of tree populations are directly related to their genetic quality.At the same time,the reproductive capacity of trees has a certain periodicity.The yield and quality of seeds will decrease if they are too old,Pinus massoniana,as one of the most important economic and ecological afforestation tree species in China,is not clear about its seed quality and genetic diversity level.Therefore,in this study,SSR marker was used for the following research on the source of seed stand of Pinus massoniana(1959 afforestation)and its four progeny plantations(afforested time in 1996,2000,2006 and 2015),located in Tianhongling forest farm,Cangwu County,Guangxi.1.The average DBH(D)was 58.87cm for the mother tree was tested.The average fresh weight of single fruit(CM),fruit length(CL)and fruit width(CW)were 14.09g,48.95mm and 24.11mm respectively.The average 1000 grain weight(TSW),germination rate(GR)and germination potential(GP)were 8.36g,70%and 45%.Mother in cone phenotype and seed traits were significantly different.Correlation analysis showed that there was no significant correlation between other traits except single fruit weight,fruit length and fruit width,germination percentage and germination potential.By using principal component analysis(PCA)and cluster analysis,the tested mother trees were divided into 5 groups.The group 1 and 2,with good seeds and large fruit shape,which could be used as the first seed collecting mother tree.2.Genetic diversity of seed stand and its four 4 different ages of progeny plantations were analyzed with 29 SSR markers.It was found that both the progeny and the seed stand were rich in genetic diversity and had a wide genetic basis.There was no significant difference among offspring plantations and seed stand on genetic diversity parameters.3.The genetic structure of the parent and four progeny stands were analyzed.The results showed that the genetic differentiation between the mother tree and the four progeny plantations was increased with the age of mother tree at seeds collecting.The genetic composition of 1996 offspring was similar to that of the seed stand,while the 2015 offspring was distinct with that of the seed stand.The mating system analysis of 7 families indicated that the rate of inbreeding was higher(tm=0.892,ts=0.695),and the inbreeding index(tm-ts=0.207)was greater than zero.The parental inbreeding coefficient F was equal to 0.207,the effective pollen donor number(n=1.754)is small,the half sib ratio is Phs is 0.430,and the full sib ratio is Pfs is 0.570.Comparing the cross rate between seed group(before germination test)and the germinated seed group,the former group displayed lower cross rate(tm=86.7%,ts=67.5%)than that of latter one(tm=91.1%,ts=76.4%),implying that the seeds germination rate was affected by cross rate.