# The Irrigation Water pH Has a Dominant Impact on the Growth and Stress Markers of Bigleaf Hydrangea
## 3 Results
### Impact of pH and EC of Irrigation Water and Hydrangea Varieties on Morpholayed Characteristics
#### 3.2.4 Impact of pH and EC of Irrigation Water and Hydrangea Varieties on Biochemical Parameters  
The irrigation water pH and EC significantly affected the MDA and proline content (Table 4). The lowest proline (659.5 \(\upmu\)mol g\({}^{-1}\) FW, Figure 6a) and MDA (0.215 \(\upmu\)mol g\({}^{-1}\) FW, Figure 6b) concentrations were recorded in the slightly acidic reaction, i.e., pH 6, while the highest proline (12881.86 \(\upmu\)mol g\({}^{-1}\) FW, Figure 6a) and MDA (1.257 \(\upmu\)mol g\({}^{-1}\) FW, Figure 6b) concentrations were measured at pH 4. As for the irrigation water EC, the lowest proline (4068.206 \(\upmu\)mol g\({}^{-1}\) FW, Figure 6c) and MDA (0.550 \(\upmu\)mol g\({}^{-1}\) FW, Figure 6d) concentrations were recorded in the EC 2 irrigation water treatment, while the highest concentrations of proline (4880.794 \(\upmu\)mol g\({}^{-1}\) FW, Figure 6c) and MDA (0.691 \(\upmu\)mol g\({}^{-1}\) FW, Figure 6d) were measured in the EC 4 treatment. In this study, no significant effect of variety on proline and MDA concentrations was recorded (Table 4). The highest proline and MDA concentrations were recorded for the Early Blue variety (Figure 6e,f). For the Early Blue variety, a very high positive correlation (r = 0.97) was found between the flower and stem number (Figure 7). A high positive correlation was found between leaf and stem number (r = 0.8), leaf and flower number (r = 0.76), and between proline and MDA concentrations (r = 0.86). A moderate positive correlation (r = 0.66) was found between leaf weight and flower weight. A low positive correlation was found between flower weight and stem number (r = 0.36), flower number (r = 0.34), and leaf number  
\begin{table}
\begin{tabular}{c c c c c c c} \hline  & \multicolumn{2}{c}{**MDA**} & \multicolumn{4}{c}{**Proline**} \\ \hline  & pH & EC & Variety & pH & EC & Variety \\ F & 176.328 & 3.875 & 2.452 & 28.35 & 11.01 & 1.181 \\ \(p\) & **0.000** & **0.013** & 0.066 & **0.000** & **0.000** & 0.281 \\ LSD\({}_{0.05}\) & 0.094 & 0.094 & 0.066 & 303.430 & 303.430 & 214.557 \\ LSD\({}_{0.01}\) & 0.125 & 0.125 & 0.088 & 403.0(r = 0.41). Furthermore, a low positive correlation was found between leaf weight and stem number (r = 0.39), flower number (r = 0.39), leaf number (r = 0.48), and between proline and flower diameter (r = 0.33). A high negative correlation was found between flower diameter and stem number (r = \(-\)0.76), flower number (r = \(-\)0.73), and between proline and leaf weight (r = \(-\)0.71). A moderate negative correlation was found between flower diameter and leaf number (r = \(-\)0.57), proline and stem number (r = \(-\)0.52), flower number (r = \(-\)0.5), leaf number (r = \(-\)0.61), and flower weight (r = \(-\)0.6). A moderate negative correlation was also found between MDA and leaf number (r = \(-\)0.51) and leaf weight (r = \(-\)0.65). A low negative correlation was found between MDA concentration and stem number (r = \(-\)0.4), flower number (r = \(-\)0.36), and flower weight (r = \(-\)0.42). Figure 6: Proline and MDA concentrations for different irrigation water pH (**a,b**), EC (**c,d**) and hydrangea varieties (**e,f**). Columns with the same letters are not significantly different. Figure 7: The analysis shows the negative (\(-\), purple) and positive (\(+\), red) correlations between morphological properties, proline, and MDA concentrations in the Early Blue hydrangea variety. The strength of the correlation and its significance are indicated by a number, while empty fields are not significant. For the Bianco hydrangea variety, a very high positive correlation (r = 0.96) was found between flower and stem number (Figure 8). A high positive correlation was found between leaf weight and leaf number (r = 0.84) and between proline and MDA concentrations (r = 0.86). A moderate positive correlation was found between flower diameter and plant height (r = 0.41) as well as between flower weight and stem number (r = 0.55) and flower number (r = 0.57).