Sampling Strategy of Primary Core Germplasm of Cinnamomum camphora in China

In order to optimize the conservation strategy of camphor tree germplasm resources and improve the utilization efficiency, we used 4 phenotypic data of 872 camphor trees in China, including seedling height, ground diameter, seed size and weight, to research the primary core germplasm sampling strategy of camphor tree in China in this study, from the aspects including grouping method, intra-group sampling proportional method, clustering method, sampling strategy, and overall sampling ratio. The results showed that the effect of the core germplasm constructed was different by 4 kinds of systematic sampling methods under different clustering methods and sampling strategies. Under the premise of determining the longest distance method and the preferential sampling strategy, the core germplasm construction of camphor tree was better by the logarithmic proportion method in the group. The range coincidence rate and coefficient of variation rate of the core germplasm screened by the longest distance method were higher than those of the other 6 methods, which was the best clustering method. The values of genetic diversity index, phenotypic frequency variance, phenotypic variance and the variable rate of coefficient of variation of core germplasm constructed by the preferential sampling method were all the best. The genetic diversity index, phenotypic retention ratio and phenotypic variance were the highest and the phenotypic frequency variance was the lowest at 25% sampling ratio, indicating which was the best sampling ratio to construct the primary core germplasm of camphor tree. Based on the analysis results of 6 parameters, the provenance-logarithmic proportion-longest distance clustering-preferential sampling method is finally determined as the optimal sampling strategy for the construction of core germplasm of camphor tree in China.