Patterns Of Pollen Contamination On 2^nd Generation Eucalyptus Pellita

Pollen contamination of forest trees not only affects the estimation of genetic parameters of forest populations,but also has a great impact on seed quality in seed orchards and reduces the genetic gain level of seed orchards.As an important fast-growing tree species and a widely used wood production tree species,E.pellita can easily hybridize with many euclaypt species hence ease to be pollen contaminated.Study on patterns of pollen comtamination on E.pellita seed orchards can effectively promote breeding,conservation and utilization of this species.In this paper,2^ndgeneration seed orchard which seed sourced from four 1^stgeneration seed orchards?Zhanjiang,Chongzuo-1,Chongzuo-2 in Guangxi,Sabah in Malaysia?were used as the research genetic material.Using morphological features and SSR molecular markers,The pollen contamination rate and sources of their contamination in different seed orchards were studied,and the effects of pollen contamination on the growth,health and flowering phenology of E.pellita were analyzed.The main results are as following:1 According to traits of the 2^ndof E.pellita leaves,all the 4 E.pellita sources with pollen contamination.Contamination rates were significantly different?P<0.05?between sources which were ranged from 18.75%to 35.50%.Family level contamination rate is 92.81%.The contamination rates between families?within source?were highly significant?P<0.001?.Pollen contamination significant effected?P<0.01?leaf morphological.traits,mainly caused:color lighter,shape narrower,wax on leaf thinner.But it didn't significantly affected leaf attitude.Pollen contamination didn't significantly affected tree volume growth and flowering phenology.But tree health index was decreased by 4.74%.That was highly significant?P<0.001?.2 Using SSR molecular marker technology to analyze the pollen contamination of four different source groups,it was found that the E.pellita in four sources were polluted,and their contamnination rate ranged from 10.87%to 26.33%.The average contamnination rate for the four sources is 18.19%.Among them,the contamnination of Chongzuo-2 in Guangxi reached26.23%,and the contamnination rate of Zhanjiang in Guangdong was 10.87%.According to statistics,74.75%of the families were polluted by eucalyptus pollen outside the seed garden.The proportion of uncontaminated families from Chongzuo-1 in Guangxi was the highest,reaching 54.54%.The contamnination rate of most families in the four sites was 0-40%,accounting for 84.34%of the entire group.According to the analysis of pollen sources from different site,the sources of pollen from the four sources are not the same.The sources of pollen contamnination from the two groups in Chongzuo,Guangxi are E.urophylla?E.grandis.The source of pollen from the Zhanjiang group in Guangdong is the Eucalyptus urophylla.The sources of exotic pollen contamnination in Sabah,Malaysia are mainly E.urophylla.3 Combined with phenotypic analysis and SSR molecular markers,it was found that the E.pellita populations at four locations were contaminated by exotic pollen,but there were some differences in the statistical results.The average contaminated rate obtained by performance anal.ysis was 27.24%,and the average pollution rate obtained by SSR molecular markers was18.19%,but the two were consistent with the trend of contaminated rate of the four groups.Both methods showed that the contamination rate of the E.pellita from Chongzuo-2 in Guangxi was the highest,and the contamination rate of the two groups was between 0%and 40%.This indicates that both methods can be used for the discrimination study of the hybrids of the E.pellita.In summary,the 2^ndgeneration E.pellita have been polluted,and SSR molecular marker technology and phenotypic traits are good judgment methods.According to the identification results at different stages of seed or forest conservation forest construction,eliminate contaminated plants and improve the purity of the gene of the E.pellita,laying the foundation for high-generation breeding.