## 2 Results
### Antioxidant Activity (ABTS\({}^{+}\) and DPPH Methods) and Total Polyphenols  
Results of antioxidant activity (AA), measured by two methods (ABTS\({}^{+}\) and DPPH), and total phenolic content (TPC) are shown in Table 1. No statistical differences between irrigation treatments were found regarding both AA methods, although a different trend was observed for TPC. Treatment 2 showed the highest value of TPC, while T1 had the smallest one. The correlation between TPC and stress level was studied, and Figure 1 shows that this correlation produced a quadratic relationship in which it could be seen that TPC increased as the minimum midday stem water potential decreased until \(-4\) MPa; at this stress level, phenols start to decrease.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **ANOVA\({}^{\ddagger}\)** & **T0** & **T1** & **T2** & **T3** \\ \hline \multicolumn{6}{c}{**Watering Technique Conditions**} \\ \hline Applied water (mm) & & 468 & 197 & 160 & 162 \\ Stress integral (MPa \(\times\) day) & NS\(\dagger\) & 53.4 & 152 & 182 & 132 \\ Min \(\psi_{\text{stem}}\) (MPa) & NS & \(-3.80\) & \(-4.00\) & \(-4.68\) & \(-4.04\) \\ Yield (kg ha\({}^{-1}\)) & NS & 7287 & 6902 & 6316 & 6764 \\ Oil Yield (\% dry weight) & NS & 28.0 & 30.4 & 30.1 & 33.0 \\ \hline \multicolumn{6}{c}{**Olive Oil Quality Parameters**} \\ \hline \multicolumn{6}{c}{Acidity index (\%)} & NS & 0.31 & 0.37 & 0.24 & 0.31 \\ Peroxide value (meq Q\({}_{2}\) kg\({}^{-1}\)) & NS & 9.29 & 8.07 & 9.36 & 10.1 \\ K\({}_{232}\) & NS & 2.15 & 1.91 & 2.14 & 2.02 \\ K\({}_{270}\) & NS & 0.10 & 0.10 & 0.11 & 0.10 \\ \(\Delta\)K & NS & \(-0.03\) & \(-0.02\) & \(-0.02\) & \(-0.02\) \\ \hline \multicolumn{6}{c}{**Antiv oxidant Activity and Total Phenol Content**} \\ \hline ABTS\({}^{+}\) (mmol Trolox eq L\({}^{-1}\)) & NS & 0.113 & 0.098 & 0.114 & 0.151 \\ DPPH (mmol Trolox eq L\({}^{-1}\)) & NS & 0.233 & 0.223 & 0.265 & 0.282 \\ TPC (mg GAE L\({}^{-1}\)) & * & 259.8 a\({}^{\ddagger}\) & 126.8 b & 267.3 a & 181.5 ab \\ \hline \multicolumn{6}{c}{\(\dagger\) NS = not significant at \(p<0.05\); *, significant at \(p<0.05\). \(\ddagger\) Values of olive oil quality parameters, antioxidant activity, and total phenolic content (TPC) (mean of 12 replications per irrigation treatments) followed by the same letter, within the same row, were not significantly different (\(p<0.05\)), according to [PERSON]’s least significant difference test. Note: Acidity index: Threshold value for extra virgin olive oil (EVOO) is \(\leq\)0.8%; peroxide value: threshold value for EVOO is \(\leq\)20 mag O\({}_{2}\) kg\({}^{-1}\); K\({}_{232}\): threshold value for EVOO is \(\leq\)2.5; K\({}_{270}\): threshold value for EVOO is \(\leq\)0.22; AK: threshold value for EVOO is \(\leq\)0.01; (EEC Regulation 25689/1). T0: control (100% Et); T1: Optimal RDI (RDI during stage II); T2: Confederation RDI (RDI during stage II using water limitation of Guadalquivirr hydrographic confederation); T3: Confederation SDI (SDI using water limitation of Guadalquivirr hydrographic confederation). ABTS\({}^{+}\): azimo-bis (3-ethylbenzothazoline-6-sulfonic acid; DPPH 2,2-diphenyl-1-pirylhydrazyl.}\) \\ \hline \end{tabular}
\end{table}
Table 1: Watering technique conditions, oil technological parameters, antioxidant activity (ABTS\({}^{+}\) and DPPH methods), and total phenol content (TPC) of “Arbequina” olive oil.