## 3 Results
### PEG Stress Tolerance Based on Proline Content and Antioxidant Enzyme Activity  
The findings of our analysis revealed that there were major variations between the genotypes under non-stress and stress conditions for the proline content and antioxidant enzyme activities (APX and CAT) (Table 7). Notable differences between these characteristics were established between the four groups (Figure 3) across the six genotypes. Larger distribution ranges were seen in the proline content (PC) under all conditions. The smallest distribution ranges between unstressed and stressed groups were revealed in APX and CAT under the T0.50 condition. Under the optimum condition (T0.00), Gwll Swr, Red Bazyan, and White Bazyan registered the best values in PC (0.31 umol/g FW), APX (0.81 nkat/mg FW), and CAT (10.49 nkat/mg FW) activities, respectively. At T0.50, the ranges of PC, APX, and CAT were from 0.21 to 0.46 umol/g FW, 0.75 to 1.11 nkat/mg FW, and 16.55 to 26.98 nkat/mg FW, respectively. Choman had the largest output values of APX and CAT actions under the T1.00 and T1.50 stress treatments and Shawre showed the maximum PC value. For the overall stress conditions, the genotypes' resistance/susceptibility rating according to the PC, APX, and CAT characteristics was as follows: Choman > Shawre > White Bazyan > Gwll Swr > Red Bazyan > Kalar (Table 8). In addition, the degree of metabolic alterations in response to stress was associated with the reported sensitivity/tolerance phenotype. \begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Stress Level** & **Index** & **Choman** & **Gwll Swr** & **Kalar** & **Red Bazyan** & **Shawre** & **White Bazyan** \\ \hline \multirow{4}{*}{T0.50} & STI & 1.06 & 0.75 & 0.54 & 0.59 & 1.05 & 1.08 \\  & AR & 2.18 & 3.64 & 5.82 & 4.73 & 3.55 & 1.09 \\ \cline{2-8}  & Rank & 2 & 4 & 6 & 5 & 3 & 1 \\ \hline \multirow{4}{*}{T1.00} & STI & 1.01 & 0.54 & 0.49 & 0.50 & 1.01 & 0.92 \\  & AR & 1.45 & 4.73 & 5.55 & 4.64 & 2.09 & 2.55 \\ \cline{2-8}  & Rank & 1 & 5 & 6 & 4 & 2 & 3 \\ \hline \multirow{4}{*}{T1.50} & STI & 1.01 & 0.53 & 0.61 & 0.55 & 0.94 & 0.74 \\  & AR & 1.18 & 5.64 & 3.18 & 4.36 & 2.73 & 3.91 \\ \cline{2-8}  & Rank & 1 & 6 & 3 & 5 & 2 & 4 \\ \hline \multirow{2}{*}{Overall} & Sum of Ranks & 4 & 15 & 15 & 14 & 7 & 8 \\ \cline{2-8}  & Overall Rank & 1 & 5 & 5 & 4 & 2 & 3 \\ \hline \end{tabular}
\end{table} 
Table 6: Rank of rice genotypes by the stress tolerance index (STI) and the average sum of ranks (ASRs) based on callus growth characters under stress conditions. Genotypes with the highest STI and lowest ASR values were considered to be the best genotypes and the best performance of each phenotype was assigned the lowest rank. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Proline Content (umo/g FW)**} & \multicolumn{4}{c}{**APX (nkat/mg FW)**} & \multicolumn{4}{c}{**CAT (nkat/mg FW)**} \\ \hline Genotype & T0.00 & T0.50 & T1.00 & T1.50 & T0.00 & T0.50 & T1.00 & T1.50 & T0.00 & T0.50 & T1.00 & T1.50 \\ \hline Choman & 0.30 a & 0.36 b & 0.40 b & 0.49 b & 0.57 b & 0.86 bc & 1.61 a & 2.32 a & 9.11 b & 26.98 a & 37.58 a & 48.91 a \\ Guill Swr & 0.31 a & 0.46 a & 0.49 a & 0.62 a & 0.54 b & 0.75 c & 1.10 c & 1.23 d & 9.66 a & 17.55 c & 25.93 c & 37.65 c \\ Kalar & 0.28 b & 0.35 b & 0.33 c & 0.56 b & 0.51 b & 0.93 abc & 1.03 c & 1.24 d & 8.99 b & 16.55 c & 22.35 d & 38.03 c \\ Red Bazyan & 0.12 d & 0.29 c & 0.34 c & 0.38 d & 0.59 a & 1.11 a & 1.27 b & 1.54 c & 10.49 a & 16.90 c & 24.56 cd & 33.21 d \\ [PERSON] & 0.16 c & 0.18 d & 0.45 a & 0.64 a & 0.52 b & 0.90 bc & 1.33 b & 1.80 b & 7.22 c & 22.63 b & 36.39 a & 49.35 a \\ White Bayaran & 0.15 c & 0.21 d & 0.31 c & 0.48 c & 0.61 a & 1.02 ab & 1.26 b & 1.59 c & 8.54 c & 22.60 b & 29.53 b & 42.96 b \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Influence of drought stress on the proline content, ascorbate peroxidase (APX), and catalase (CAT) activities in the callus of six rice genotypes. The results displayed are the average of three replicates.