## 3 Results
### Effect of Chilling Stress on the Physiological Indices of Leafy Mustard
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Index** & **Treatment** & **Minimum** & **Maximum** & **Mean** & \
\begin{tabular}{c} **Standard** \\ **Deviation** \\ \end{tabular} &
\begin{tabular}{c} **Coefficient of** \\ **Variation\%** \\ \end{tabular} \\ \hline Chl & \(5\,^{\circ}\mathrm{C}\) & 0.37 & 2.65 & 1.14 & 0.47 & 41.07 \\  & \(25\,^{\circ}\mathrm{C}\) & 0.08 & 2.23 & 0.94 & 0.45 & 47.89 \\  & \(5\,^{\circ}\mathrm{C}\) & 0.17 & 3.42 & 0.99 & 0.70 & 70.58 \\ SS & \(25\,^{\circ}\mathrm{C}\) & 0.07 & 2.51 & 0.54 & 0.51 & 92.93 \\ Pro & \(5\,^{\circ}\mathrm{C}\) & 17.01 & 303.53 & 56.84 & 61.42 & 108.06 \\  & \(25\,^{\circ}\mathrm{C}\) & 16.38 & 253.47 & 27.28 & 29.41 & 107.81 \\ SOD & \(5\,^{\circ}\mathrm{C}\) & 155.04 & 350.83 & 251.39 & 42.26 & 16.81 \\  & \(25\,^{\circ}\mathrm{C}\) & 54.78 & 300.2 & 134.02 & 60.05 & 44.81 \\ POD & \(5\,^{\circ}\mathrm{C}\) & 1027.39 & 4327.89 & 1953.05 & 702.05 & 35.95 \\  & \(25\,^{\circ}\mathrm{C}\) & 1316.39 & 3843.67 & 2604.16 & 681.63 & 26.17 \\  & \(5\,^{\circ}\mathrm{C}\) & 66.42 & 861.33 & 379.14 & 194.27 & 51.24 \\  & \(25\,^{\circ}\mathrm{C}\) & 78.42 & 790 & 254.16 & 151.65 & 59.67 \\  & \(5\,^{\circ}\mathrm{C}\) & 0.73 & 68.92 & 6.00 & 13.60 & 226.85 \\  & \(25\,^{\circ}\mathrm{C}\) & 0.42 & 26.88 & 2.94 & 4.48 & 152.36 \\  & \(5\,^{\circ}\mathrm{C}\) & 0.60 & 0.84 & 0.79 & 0.04 & 5.22 \\  & \(25\,^{\circ}\mathrm{C}\) & 0.66 & 0.85 & 0.80 & 0.04 & 4.71 \\  & \(5\,^{\circ}\mathrm{C}\) & 0.53 & 0.79 & 0.70 & 0.05 & 6.53 \\  & \(25\,^{\circ}\mathrm{C}\) & 0.61 & 0.79 & 0.73 & 0.04 & 5.73 \\  & \(5\,^{\circ}\mathrm{C}\) & 0.07 & 0.54 & 0.25 & 0.10 & 40.42 \\  & \(25\,^{\circ}\mathrm{C}\) & 0.06 & 0.45 & 0.30 & 0.09 & 29.52 \\  & \(5\,^{\circ}\mathrm{C}\) & 0.17 & 1.67 & 0.66 & 0.32 & 48.26 \\  & \(25\,^{\circ}\mathrm{C}\) & 0.18 & 1.54 & 0.51 & 0.20 & 39.18 \\ qP & \(5\,^{\circ}\mathrm{C}\) & 0.11 & 0.71 & 0.36 & 0.14 & 39.42 \\  & \(25\,^{\circ}\mathrm{C}\) & 0.09 & 0.60 & 0.41 & 0.11 & 27.23 \\  & \(5\,^{\circ}\mathrm{C}\) & 0.40 & 2.95 & 1.30 & 0.59 & 45.02 \\ Rfd & \(25\,^{\circ}\mathrm{C}\) & 0.39 & 2.10 & 1.21 & 0.35 & 29.03 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Analysis of variation physiological indices of leafy mustard under chilling stress. Correlation analysis of the chilling tolerance coefficients of 13 indices in 65 leafy mustard cultivars is shown in Figure 1. As the correlation coefficient values approaches 1 or \(-1\), it indicates a strong relationship between the variables. Specifically, there was a significant negative correlation between SS content and POD activity, and a highly significant negative correlation between SS content and Fv\({}^{\prime}\)/Fm\({}^{\prime}\), with correlation coefficients of \(-0.30\) and \(-0.42\), respectively. Meanwhile, there was a significant positive correlation between SS content and NPQ, with a correlation coefficient of 0.31. SOD activity showed a significant positive correlation with CAT activity, with a correlation coefficient of 0.31. POD activity showed a highly significant positive correlation with CAT activity and a significant negative correlation with NPQ, with correlation coefficients of 0.43 and \(-0.25\), respectively. Fv/Fm showed a significant positive correlation with Fv\({}^{\prime}\)/Fm\({}^{\prime}\) and NPQ, with correlation coefficients of 0.72 and 0.32, respectively. Additionally, it was significantly positively correlated with Rfd, with a correlation coefficient of 0.31. Fv\({}^{\prime}\)/Fm\({}^{\prime}\) was highly significantly negatively correlated with NPQ, with a correlation coefficient of \(-0.37\). \(\Phi\)PSII was highly significantly positively correlated with qP and Rfd, with correlation coefficients of 0.97 and 0.57, respectively. NPQ was highly significantly positively correlated with Rfd and significantly positively correlated with qP, with correlation coefficients of 0.71 and 0.24, respectively. Finally, qP was highly significantly positively correlated with Rfd, with a correlation coefficient of 0.62.