## 3 Results
### Response of Plant Root Growth to Varying Flooding Durations
#### 3.1.2 Root Diameter Percentages  
There were significant differences (\(p<0.05\)) in the root proportions of the three plants: _Carex_, _Cynodon_, and _Eleusine_. The effects of varying flooding durations on the D5 diameter classes of the root systems of each plant were particularly pronounced (Figure 3). As the duration of flooding increased, the percentage of D1 (<0.2 cm) for the three plants initially increased but then decreased, reaching maximum values of 57.08%, 14.62%, and 6.51% after 90 days, respectively. The percentage of _Carex_ in D2 (0.2\(\sim\)0.3 cm) increased and then decreased with prolonged flooding, while _Cynodon_ tended to decrease, followed by an increase. _Eleusine_ displayed a trend similar to that of _Carex_. The three species reached maximum values of 8.43%, 21.75%, and 16.3% at 120, 150, and 90 days, respectively. In  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Species** & **Parameters** & **Equation** & **R\({}^{2}\)** & **Significance** \\ \hline \multirow{5}{*}{_Carex_} & Diameter & \(y=0.62+4.45\times 10^{-4}x-7.5\times 10^{-7}x^{2}\) & 0.74 & \textless{}0.05 \\  & Length & \(y=686.79+8.28x-4.02\times 10^{-2}x^{2}\) & 0.83 & \textless{}0.01 \\  & Surface area & \(y=140.99+1.69x-8.17\times 10^{-3}x^{2}\) & 0.94 & \textless{}0.01 \\  & Volume & \(y=2.17+2.76\times 10^{-2}x-1.16\times 10^{-4}x^{2}\) & 0.80 & \textless{}0.01 \\  & Diameter & \(y=0.64+1.90\times 10^{-4}x-2.51\times 10^{-7}x^{2}\) & 0.58 & \textless{}0.05 \\  & Length & \(y=735.79+3.55x-1.88\times 10^{-2}x^{2}\) & 0.82 & \textless{}0.01 \\  & Surface area & \(y=149.00+0.47x-2.45\times 10^{-3}x^{2}\) & 0.77 & \textless{}0.01 \\  & Volume & \(y=2.42+4.38\times 10^{-3}x-1.67\times 10^{-5}x^{2}\) & 0.95 & \textless{}0.01 \\  & Diameter & \(y=0.67+4.37\times 10^{-4}x-4.97\times 10^{-7}x^{2}\) & 0.90 & \textless{}0.01 \\  & Length & \(y=394.49-0.16x-1.93\times 10^{-3}x^{2}\) & 0.84 & \textless{}0.01 \\  & Surface area & \(y=68.78+0.40x-2.03\times 10^{-3}x^{2}\) & 0.89 & \textless{}0.01 \\  & Volume & \(y=1.14+1.44\times 10^{-3}x-1.20\times 10^{-5}x^{2}\) & 0.95 & \textless{}0.01 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Fitting equation for root morphology and flooding duration.  
Figure 2: Variation in root morphology with varying flooding durations. (**A**) represents Relationship between Waterlogging Duration and Plant Diameter; (**B**) represents Relationship between Waterlogging Duration and Total Root Length; (**C**) represents Relationship between Waterlogging Duration and Total Root Surface Area; (**D**) represents Relationship between Waterlogging Duration and Total Root Volume.  
D3 (0.3-0.4 cm), varying the flooding duration did not significantly affect the percentages roots of _Carex_ or _Cynodon_, which reached maximum values of 8.41% and 22.31% at 90 and 150 days, respectively. The percentage of the D3 diameter class of _Eleusine_ tended to increase, followed by a decrease as the flooding duration increased, with maximum values of 8.41%, 22.31%, and 23.01% at 90, 150, and 90 days, respectively. In D4 (0.4-0.5 cm), the maximum percentages for the three plants were recorded at 60, 150, and 90 days, with values of 8.28%, 15.05%, and 19.6%, respectively. In D5 (>0.5 cm), the percentage of _Carex_ decreased initially but then increased with prolonged flooding, whereas _Cynodon_ displayed an increasing trend followed by a decrease. _Eleusine_, on the other hand, showed an overall decreasing trend followed by increasing trend after reaching a maximum value at 30 days of flooding. The three species reached their maximum values at 180, 90, and 30 days, with percentages of 26.98%, 31.71%, and 50.37%, respectively. Notably, at the time of sampling, the above-ground portion of the 120-day-old _Eleusine_ sample had completely ceased shedding and no longer exhibited growth with increasing flooding duration.