| Sapium sebiferum is one of the native trees which is widely distributed in China. It is a mult-fuction woody species, such as energy resources, medicinal value, timber wood and ornamental applicaton. Ten S. sebiferum populations in Chuan-yu area were selected in this research to study on its genetic diversity according to determining the phenotypic traits of seeds and seedlings of offspring, and the genetic diversity between families of inter-population and intra-population was also analyzed. The core collection (eighty one samples) was screened out from primary two hundreds and seventy families. This research was aimed to supply scientific and theoretical basis for the resource evaluation, protection and preservation, genetic improvement of S. sebiferum. The results were as follows.(1) The phenotypic characters of S. sebiferum seeds inter-population and intra-population had profuse genetic variation. Qualitative character of seeds was more stable than shape index. The variation coefficient of different seed characters was range from 6.84%to 39.54%, with the average of 16.78%. The repeatability of each seed character was range from 0.31 to 0.98, with the average of 0.61. The phenotypic multiplicity degree was range from 0.40 to 0.65, with the average of 0.56. The Shannon information index was range from 0.69 to 1.07, with the average of 0.92. Each genetic diversity index of population of Youxian was best, it showed that Youxian may be the diversity distribution center of germplasm resources of S. sebiferum. The phenotypic differentiation coefficient was range from 6.71% to 42.72%, with the average of 25.47%, it showed that variation intra-population was higher than that of inter-population. Most of the sixteen seed phenotypic characters were significantly correlation. The seed phenotypic variation of S. sebiferum intra-population presented one way variation pattern with latitude in space distribution, and the variation was mainly controlled by low temperature. According to UPGMA cluster analysis by Euclidean distance inter-population, the nine populations of S. sebiferum could be classified to four types.(2) The variation coefficient of height, basal diameter, lateral root number, main root length and branch number of S. sebiferum offspring was range from 19.78%to 34.32%, 15.4% to 21.79%,31.60% to 40.14%,18.97% to 25.08% and 25.1% to 69.67% respectively, with the average of 27.1%,19.54%,36.61%,21.01%and 55.56%. The average genetic differentiation coefficient of S. sebiferum was 17.6287%. it showed that the variation intra-population was significantly higher than that of inter-population in seedling stage of S. sebiferum. The family heritability of height, basal diameter, lateral root number, main root length and branch number was 0.55,0.60,0.43,0.49 and 0.56 respectively, while their individual heritability was 0.81,0.87,0.54,0.55 and 0.76 respectively. Height was significantly correlation with basal diameter and main root length, the correlation coefficient was 0.788 and 0.839 respectively. Basal diameter was also significantly correlation with main root length, and the con-elation coefficient was 0.770. According to UPGMA cluster analysis by Euclidean distance inter-population, the S. sebiferum populations could be classified to three types, and it was same to the results of cluster analysis of phenotypic characteristics.(3) The phenotypic data of 270 parts of S. sebiferum germplasm materials were clustered by UPGMA method, and established 81 parts of core collection, the evaluation result showed that the average value, standard deviation, range value, variation coefficient, phenotypic diversity degree and Shannon information index of sixteen seed traits of core collection were highly coincidence with primary populations, the coincidence rate was 96.50%,91.64%, 91.55%,96.33%,97.90%and 97.93%respectively. The first five principal components of core collection had represented the genetic diversity of eighty eight percents of primary populations. The characteristic value of each principal component was similar to that of primary populations. The F test result showed that there had no significantly difference between the sixteen phenotypic traits of preliminary core collection and primary populations, it showed that this eighty one core germplasm resources samples could represent the genetic diversity of primary populations excellently.(4) Based on the germplasm resource research, a preservation gene bank was established by using the split plot experiment design, which included ten populations of one hundred and fifty families, its land area was one hundred and thirty five acre, and it is the only gene bank in China of S. sebiferum for regional allopatry preservation. |
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