Statistical analysis
Using SPSS 23.0, data were analyzed using nested design ANOVA, multiple comparison analysis, correlation analysis, and principal component analysis; and oil content and fatty acid fractions were thoroughly investigated utilizing the method of affiliation function and principal component analysis[21].
The affiliation function method was used for evaluation: the affiliation function value of each index was calculated, and the average value of the affiliation function value of each index was used as the evaluation standard; the larger the average value of the affiliation function, the better the effect, and the overall quality of A. truncatum seed oil.
\begin{equation} R(X_{j})=\frac{X_{j}-X_{\min}}{X_{\max}-X_{\min}}\nonumber \\ \end{equation}
Where: Xj is the measured index value,Xmin and Xmax refer to the minimum and maximum values of all measured values, respectively.
Results
Seed Kernel Oil Content and Fatty Acid Fractions in Inter- and Intra-population Groups
In Table 3, the findings from the analysis of 70 samples from 9 populations to determine the oil content and main fatty acid components of A. truncatum seed kernels are shown. According to Table 3, the seed kernel oil content of differed greatly among different populations, with AWH-5 having the highest oil content (50.11%) and SJN-14 having the lowest oil content (14.43%), a difference of about three times. According to 58.6% of the total experimental material, 41 of the 70 samples had oil content above average, showing that the distribution ofA. truncatum germplasm resources was quite even in terms of seed kernel oil content level. AWH (46.77%), SX (36.95%), and JXZ (33.47%) were the three populations with higher-than-average oil content among populations, and SJN had the lowest seed kernel oil content (28.35%). The average oil content of the nine populations ranged from 28.35% to 46.77%, and the average oil content among populations was 33.26%. For populations and sample people, the areas corresponding to the extremes of seed kernel oil concentration were essentially the same. The average coefficient of variation of seed kernel oil content was 21.64%, indicating that the oil content of seed kernels of A. truncatumhas a rich degree of variation, which can be used as a basis for the screening of A. truncatum ’s high-oil germplasm resources.
In 70 samples of A. truncatum , 37 fatty acid fractions were experimentally identified; the chromatograms of these samples are presented in Fig. 1 (where the chromatogram of the STA-1 sample is used as an example). A total of 19 fatty acid fractions were found, but 6 of them—myristic acid, heptadecanoic acid, eicosanoid, docosapentaenoic acid, palmitoleic acid, and methyl docosahexaenoate—had concentrations that could be ignored and were less than 0.1%, thus they were not included in the table. According to Table 3’s findings, the average amounts of each fatty acid portion in the Genboldia seed kernel are, in descending order: linoleic acid (21.11%) > oleic acid (17.45%) > erucic acid (14.28%) > eicosapentaenoic acid (6.36%) > neuronic acid (5.54%) > palmitic acid (3.44%) > stearic acid (1.70%) > α-linolenic acid (1.13%) > Behenic acid (0.72%) > eicosanoic acid (0.35%) > gamma-linolenic acid (0.33%) > eicosadienoic acid (0.19%) > arachidic acid (0.19%). The neuronic acid content of the 70 samples ranged from 2.78% to 10.80%, with a mean value of 5.54%; the sample with the highest content was STA-4 (10.80%), followed by SJN-9 (10.35%) and STA-7 (10.26%), and the sample with the lowest content was SXA-6 (2.78%), with a rise of up to 288%; the neuronic acid content of the 9 populations was also examined. The extreme difference was 4.45%, with STA having the greatest percentage (7.74%) and SXA having the lowest (3.29%). It appears that the distribution of variance in oil content and fatty acid fractions of A. truncatumseed kernels was reasonably even since the sites corresponding to the extremes of oil content and neuronic acid concentration of the samples and populations were the same. The coefficients of variation of the components ranged from 24.13% to 38.20%, with an average coefficient of variation of 31.21%, and the larger coefficients of variation indicated that the fatty acid fractions of A. truncatum seed kernels were more rich in variation; the coefficients of variation for oleic acid were the smallest among the fatty acid fractions (24.13%), and eicosapentaenoic acid was the largest (38.20%), suggesting that oleic acid variations are relatively stable, whereas The coefficient of variation of eicosadienoic acid was 33.40%, indicating that the test material possessed the material basis for screening the high neuronic acid-specific germplasm.