## 3 Results
### Comparison of Biospeckle Contrast of Seeds after AMD Exposure for 48 h and Biomass after 7 Days  
The percentages of seeds germinated at 48 h under different treatments were the same (Figure 4), and there was no noticeable difference in appearance. Therefore, we decided to investigate if there are differences in the internal activity of seeds at 48 h. The bOCT method was used to monitor the seeds under different treatments, which did not damage the germinated seeds and was beneficial to observe the subsequent growth of seeds. The OCT images of the Kaiware daikon seeds exposed under different AMD concentrations of the control, 40 mL/L, and 80 mL/L AMD after an exposure of 48 h to AMD are shown in Figure 5a-c. There were no significant differences seen in the structural images with the change of treatment. The bOCT images of seeds exposed to different treatments for 48 h are shown, respectively, in Figure 5d-f. A clear difference could be seen due to different AMD concentrations. The temporal variation is higher in the red regions compared to the blue regions. The blue part was more in the AMD treatment than in the control, indicating that the temporal variations in the AMD treatments were lower than that in the control after 48 h. The temporal change in the 80 mL/L AMD treatment was lower than that in the 40 mL/L AMD treatment. Figure 6 is obtained by calculating the averaged biospeckle contrast of six seeds under each treatment. The results showed that there were significant differences between the treatments. The contrasts of seeds under AMD treatments were significantly lower than that of the control, and the biospeckle contrast of seeds exposed to 80 mL/L AMD was significantly lower than that under 40 mL/L AMD (Figure 6). Figure 4: Percentage of seed germination under different treatments. After 7 days, the biomasses of kaiware daikon under each treatment were measured. Figure 7 shows the photograph of the plants' growth under different treatments after 7 days. Depending on AMD treatment levels, the plants growth was significantly different with clear changes in appearance. At the same time, the shoot length, root length, shoot root ratio (RS ratio), fresh weight, dry weight, and water content of the plant were measured (Figures 8 and 9). There were significant differences in shoot length between treatments (Figure 8). The difference in root length between the control and 80 mL/L AMD treatment was significant but not significant with 40 mL/L AMD treatment. There was a significant difference in the ratio of root to shoot between the control and 80 mL/L AMD treatment, but the difference with 40 mL/L AMD treatment was not significant. These results reveal that AMD inhibits shoot growth, and high concentration AMD inhibits root growth. Figure 5: Cross sections of OCT structural (top row) and bOCT (bottom row) images after 48 h of AMD exposure for (**a**,**d**) 0 mL/L or the control, (**b**,**e**) 40 mL/L, and (**c**,**f**) 80 mL/L. Figure 6: Averaged biospeckle contrast value of seeds under different treatments after 48 h exposure. (Different letters, a b c, represent statistical differences between treatments; the error bar represents standard deviation; Fisher-LSD multiple comparison; \(p<0.05\) level, Number N = 6). The differences in fresh weight between treatments were significant but not in dry weight (Figure 9). The difference between the fresh weight water content of the plants under the control and 80 mL/L AMD treatment was significant, and the difference with 40 mL/L AMD treatment was not significant. The results indicate that 80 mL/L AMD reduces the water content of Kaiware daikon. The tendency of plant growth after 7 days was consistent with the bOCT results at 48 h, indicating that the bOCT results could reveal internal activity of the seed much in advance. In addition, there were obvious differences in the morphology of the roots under different treatments (Figure 7). The roots of the plants under 80 mL/L AMD were very short or almost non-existent.