Note: * mean significant different at 0.05 level; ** mean significant different at 0.01 level.
Principal Component Analysis
The oil content of seed kernels and the main fatty acid fractions of 70 A. truncatum samples from nine populations were subjected to principal component analysis, and two principal components were extracted by analyzing the degree of contribution of each index, screening out independent variables with dominant roles, and using an eigenvalue greater than one as the principle (the results are shown in Table 7). As can be seen in Table 7, the cumulative contribution of the first 2 principal components is as high as 84.29%, which has been able to explain most of the information. In the 1st principal component, palmitic acid, stearic acid, oleic acid, linoleic acid, eicosapentaenoic acid, erucic acid, and neuronic acid contents were more highly correlated with PC1, and the absolute value of the loading was higher, all of which were greater than 0.8, so the 1st principal component can be summarized as the fatty acid component playing a major contributing role; in the 2nd principal component, the oil content of the seed kernel of A. truncatum had the largest absolute value of the loading, and thus the 2nd principal component mainly contained the seed oil content. In summary, the difference between the oil content of A. truncatum seed kernels and the major fatty acid fractions was large, which was the same as the results of the previous analysis of variance, and the contribution of the major fatty acid fractions was more than that of the oil content of the seed kernels, indicating that the fatty acid fractions played a major contributing role in the variation of the seed oil of A. truncatum .
Table 7. Principal component analysis of seed kernel oil content and main fatty acid components in Acer truncatum