## 3 Results
### Response of Various Plant Root Mechanical Properties to Different Flooding Durations
#### 3.2.3 Elastic Modulus of the Root  
The duration of flooding stress significantly influenced the mechanical characteristics of plant roots, and species-specific responses were observed in terms of elastic modulus. Specifically, _Carex_ (Figure 6A) exhibited a notably higher elastic modulus values in smaller-diameter roots (\(<\)0.2 cm), decreasing gradually with prolonged flooding durations. Its elastic modulus sensitivity to diameter changes was enhanced in short- to medium-term flooding (as indicated by increased R\({}^{2}\) values compared to non-flooded conditions; Table 4). The elastic modulus of _Cynodon_ roots (Figure 6B) also decreased significantly with increasing diameter, yet exhibited a notable decline in fitting quality at 90 days of flooding (R\({}^{2}\) = 0.24, \(p\) > 0.05; Table 4), further indicating mechanical instability during this period. Similarly, _Eleusine_ (Figure 6C) displayed a negative correlation between diameter and elastic modulus, yet its response to flooding differed somewhat. The significance of the fitting equation decreased notably at 60 days of flooding (\(p\) > 0.05), confirming potential structural adaptation or damage during early flooding stages. However, following prolonged flooding (150-180 days), the fitting accuracy and significance rebounded markedly (R\({}^{2}\) > 0.77, \(p\) < 0.01), indicating the gradual stabilization of root mechanical properties under long-term flooding stress.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{**Flooding**} & \multicolumn{2}{c}{_Carex_} & \multicolumn{4}{c}{_Cynodon_} & \multicolumn{4}{c}{_Elusine_} \\ \cline{2-10}
**Durations (Days)** & **Equation** & **R\({}^{2}\)** & **Significance** & **Equation** & **R\({}^{2}\)** & **Significance** & **Equation** & **R\({}^{2}\)** & **Significance** \\ \hline
0 & \(y=252.5x^{-0.69}\) & 0.62 & \(<\)0.05 & \(y=348.3x^{-0.41}\) & 0.71 & \(<\)0.01 & \(y=506.7x^{-0.33}\) & 0.84 & \(<\)0.01 \\
30 & \(y=219.6x^{-0.94}\) & 0.95 & \(<\)0.01 & \(y=282.7x^{-0.34}\) & 0.60 & \(<\)0.05 & \(y=276.3x^{-0.61}\) & 0.76 & \(<\)0.01 \\
60 & \(y=197x^{-1.03}\) & 0.93 & \(<\)0.01 & \(y=270.15x^{-0.99}\) & 0.76 & \(<\)0.01 & \(y=205.5x^{-0.68}\) & 0.45 & \(>\)0.05 \\
90 & \(y=239.9x^{-1.16}\) & 0.89 & \(<\)0.01 & \(y=545.9x^{-0.99}\) & 0.24 & \(>\)0.05 & \(y=331.4x^{-1.22}\) & 0.68 & \(<\)0.01 \\
120 & \(y=434.6x^{-0.63}\) & 0.64 & \(<\)0.05 & \(y=241.8x^{-0.99}\) & 0.47 & \(>\)0.05 & \(y=177.4x^{-1.65}\) & 0.92 & \(<\)0.01 \\
150 & \(y=489.1x^{-1.88}\) & 0.98 & \(<\)0.01 & \(y=415.8x^{-0.59}\) & 0.43 & \(>\)0.05 & \(y=289.6x^{-1.22}\) & 0.77 & \(<\)0.01 \\
180 & \(y=149.9x^{-1.41}\) & 0.72 & \(<\)0.01 & \(y=382.5x^{-0.83}\) & 0.71 & \(<\)0.01 & \(y=217.6x^{-1.21}\) & 0.81 & \(<\)0.01 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Fitting equation for elastic modulus and root diameter.  
Figure 5: Effect of diameter on single root tensile strength under different flooding treatments of plants: (**A**) represents _Carex_; (**B**) represents _Cynodon_; (**C**) represents _Eleusine_; the range of 0 to 180 indicates the number of days for various flooding treatments.