## 2 Materials and Methods
### Relationship between Seed Vigor and Chlorophylll Content of Astragalus Seeds  
The chlorophylll contents of different _Astragalus_ seeds could be predicted based on the R and G values. In order to further demonstrate the relationship between the vitality of _Astragalus_ seeds and the chlorophylll content, we conducted germination tests of _Astragalus_ seeds with known chlorophyll content and grouped them based on the R values and G values. The results are given in Table 4. The proportion of high-quality seeds of seeds with R > 80 was significantly lower than that of seeds with R \(\leq\) 80. The germination percentage, hard-seed percentage, high-quality seed percentage, abnormal seedling percentage and mildew percentage of seeds with R > 90 were significantly lower than those with R \(\leq\) 90, in which the germination percentage was only about 8.7% and the high-quality seed percentage was only about 37.7%. Similarly, G values show similar laws. The germination percentage and the percentage of the high-quality seed with G \(\leq\) 55 were significantly higher than those with G > 55, and the percentage of the high-quality seed reached about 98.3%. Among the seeds with G > 55, the seeds with G > 70 were significantly lower than other seeds in all aspects, and the percentage of the high-quality seed was about 81.0%.  
Figure 9 is a box plot between R values (a) and G values (b) of different groups and their corresponding high-quality seed percentage. As can be seen from Figure 9, different high-quality seed percentage correspond to different R value and G value ranges.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**R or G Value** & \begin{tabular}{c} **Chlorophylll** \\ **Content (mg/g)** \\ \end{tabular} & \begin{tabular}{c} **Germination** \\ **Percentage (\%)** \\ \end{tabular} & \
\begin{tabular}{c} **Hard Seed** \\ **Percentage (\%)** \\ \end{tabular} &
\begin{tabular}{c} **High-Quality Seed** \\ **Percentage (\%)** \\ \end{tabular} \\ \hline R \(\leq\) 60 & 0.289 \(\pm\) 0.023 e & 54.3 \(\pm\) 5.9 a & 40.7 \(\pm\) 4.9 bc & 95.0 \(\pm\) 1.0 a \\
60 \(<\) R \(\leq\) 70 & 0.390 \(\pm\) 0.022 d & 40.7 \(\pm\) 4.7 b & 53.7 \(\pm\) 5.9 a & 94.3 \(\pm\) 2.3 a \\
70 \(<\) R \(\leq\) 80 & 0.524 \(\pm\) 0.038 c & 44.3 \(\pm\) 5.9 ab & 47.3 \(\pm\) 4.0 ab & 91.7 \(\pm\) 2.5 a \\
80 \(<\) R \(\leq\) 90 & 0.722 \(\pm\) 0.024 b & 39.7 \(\pm\) 3.8 b & 34.0 \(\pm\) 4.4 cd & 73.7 \(\pm\) 0.6 b \\ R \(>\) 90 & 0.971 \(\pm\) 0.033 a & 8.7 \(\pm\) 8.1 c & 29.0 \(\pm\) 7.0 d & 37.7 \(\pm\) 15.0 c \\ \hline G \(\leq\) 55 & 0.300 \(\pm\) 0.026 e & 58.3 \(\pm\) 2.5 a & 40.0 \(\pm\) 2.6 b & 98.3 \(\pm\) 2.1 a \\
55 \(<\) G \(\leq\) 60 & 0.372 \(\pm\) 0.012 d & 47.3 \(\pm\) 2.5 b & 47.3 \(\pm\) 2.5 ab & 94.7 \(\pm\) 0.6 b \\
60 \(<\) G \(\leq\) 65 & 0.485 \(\pm\) 0.033 c & 42.7 \(\pm\) 5.0 b & 52.0 \(\pm\) 4.0 a & 94.7 \(\pm\) 1.2 b \\
65 \(<\) G \(\leq\) 70 & 0.526 \(\pm\) 0.040 b & 43.0 \(\pm\) 7.0 b & 49.7 \(\pm\) 6.0 a & 92.7 \(\pm\) 1.2 b \\ G \(>\) 70 & 0.696 \(\pm\) 0.052 a & 42.7 \(\pm\) 6.7 b & 38.3 \(\pm\) 6.5 b & 81.0 \(\pm\) 2.6 c \\ \hline \end{tabular} Notes: The means followed by different lowercase letters are significantly different at the 0.05 level.  
\end{table}
Table 4: Statistics of germination percentage and hard seed percentage of _Astragalus_ seeds in different R and G value groups.  
Figure 8: The linear relationships between the R value (**a**) and G value (**b**) and chlorophylll content.  
The lower the R and G values, the higher the percentage of high-quality seeds; that is, the lower the chlorophyll content, the higher the percentage of high-quality seeds (Figure 10). At the same time, this study also provided a reference for the selection of mature, viable _Astragalus_ seeds.