## 3 Results
### Response of Various Plant Root Mechanical Properties to Different Flooding Durations
#### 3.2.2 Tensile Strength of the Root  
Under flooding conditions, all three plant species demonstrated a negative correlation between root diameter and tensile strength. Specifically, for _Carex_ (Figure 5A), tensile strength initially increased and subsequently decreased with prolonged flooding duration. Nevertheless, small-diameter roots showed a relatively stable tensile strength compared to larger roots and the overall mechanical stability remained relatively consistent, as evidenced by high fitting significance across most flooding durations. For _Cynodon_ (Figure 5B), a similar overall trend was observed; however, the differences in tensile strength among roots of various diameters under different flooding durations were not significant. Notably, at 90 days of flooding; the fitting significance markedly decreased (R\({}^{2}\) = 0.32; \(p\) > 0.05), suggesting notable mechanical instability at this stage. _Elusine_ (Figure 5C) exhibited a trend more similar to that of _Cynodon_, with significantly lower fitting quality and significance at 90 days (R\({}^{2}\) = 0.32; \(p\) > 0.05, Table 3). For both species, however, the negative correlation between root diameter and tensile strength remained robust across other flooding intervals. Overall; while _Carex_ and _Cynodon_ exhibited peak tensile strengths at intermediate flooding durations (90 days); _Carex_ demonstrated superior mechanical stability under flooding stress compared to the other two species. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **Flooding** \\ **Durations (Days)** \\ \end{tabular} } & \multicolumn{2}{c}{_Carex_} & \multicolumn{2}{c}{_Cynodon_} & \multicolumn{2}{c}{_Elusine_} \\ \cline{2-10}  & **Equation** & **R\({}^{2}\)** & **Significance** & **Equation** & **R\({}^{2}\)** & **Significance** & **Equation** & **R\({}^{2}\)** & **Significance** \\ \hline
0 & \(y=12.87x^{1.11}\) & 0.96 & \textless{}0.01 & \(y=13.23x^{1.40}\) & 0.97 & \textless{}0.01 & \(y=9.75x^{0.99}\) & 0.97 & \textless{}0.01 \\
30 & \(y=12.22x^{1.01}\) & 0.93 & \textless{}0.01 & \(y=15.95x^{1.54}\) & 0.93 & \textless{}0.01 & \(y=9.39x^{0.88}\) & 0.96 & \textless{}0.01 \\
60 & \(y=10.38x^{1.22}\) & 0.93 & \textless{}0.01 & \(y=13.14x^{1.26}\) & 0.89 & \textless{}0.01 & \(y=8.74x^{0.69}\) & 0.70 & \textless{}0.01 \\
90 & \(y=10.25x^{0.81}\) & 0.93 & \textless{}0.01 & \(y=10.97x^{0.90}\) & 0.47 & \textgreater{}0.05 & \(y=6.17x^{0.27}\) & 0.04 & \textgreater{}0.05 \\
120 & \(y=7.84x^{0.80}\) & 0.25 & \textgreater{}0.05 & \(y=8.73x^{0.90}\) & 0.86 & \textless{}0.01 & \(y=5.27x^{0.64}\) & 0.35 & \textgreater{}0.05 \\
150 & \(y=8.58x^{0.951}\) & 0.86 & \textless{}0.05 & \(y=5.88x^{0.66}\) & 0.70 & \textless{}0.01 & \(y=4.23x^{0.65}\) & 0.77 & \textless{}0.01 \\
180 & \(y=4.9x^{0.70}\) & 0.61 & \textless{}0.05 & \(y=4.88x^{0.75}\) & 0.75 & \textless{}0.01 & \(y=6.32x^{1.13}\) & 0.54 & \textless{}0.05 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Fitting equation for tensile force and root diameter. Figure 4: Effect of diameter on the tensile force of single root under different flooding treatments in plants: (**A**) represents _Carex_; (**B**) represents _Cynodon_; (**C**) represents _Elusine_; the range of 0 to 180 indicates the number of days for various flooding treatments.