## 3 Results  
Effect of the Treatments on the Growth, Yield, and Fruit Characteristics of the Olive Tree and Quality Parameters of the Olive Oil over a Period of 3 Years  
The growth and production of the trees were not significantly affected by the presence of _Ailanthus_ or the implementation of deficit irrigation (Table 1). However, both treatments, individually, resulted in a reduction in oil content compared to the control, while the combination of _Ailanthus_ presence under deficit irrigation resulted in the lowest olive oil percentage. Deficit irrigation resulted in a significant reduction in fruit weight and dimensions compared to full irrigation (Table 2). In particular, deficit irrigation, irrespective of the presence of _Ailanthus_, resulted in smaller fruits with reduced length and diameter. In addition, fruit length was significantly reduced by deficit irrigation in the presence of _Ailanthus_. Full irrigation resulted in lower fruit color parameters but in an increased maturity index compared to deficit irrigation (Table 3). When applied in the presence of _Ailanthus_, deficit irrigation significantly increased the chroma value of fruits and decreased the maturity index, compared to the combination of full irrigation in the absence of _Ailanthus_. \begin{table} \begin{tabular}{c c c c c c} \hline \hline  & **Increment (cm)** & **TCSA (cm2)** & **Fruit Yield/Tree (kg)** & **Olive Oil (\% _w/w_ of Olive Paste)** & **Olive Oil/Tree (kg)** \\ \hline Treatment & & & & & \\  C (Control) & 15.72 a & 0.55 a & 0.21 a & 15.91 a & 0.03 a \\  A (_Ailanthus_) & 10.65 a & 0.46 a & 0.22 a & 12.85 b & 0.03 a \\  Irrigation regime & & & & & \\  C (Full) & 13.17 a & 0.48 a & 0.21 a & 16.24 a & 0.03 a \\  D (Deficit) & 13.20 a & 0.53 a & 0.22 a & 12.52 b & 0.03 a \\  Treatment \(\times\) Irrigation regime & & & & \\  C \(\times\) F & 13.71 a & 0.52 a & 0.18 a & 16.44 a & 0.02 a \\  C \(\times\) D & 17.73 a & 0.58 a & 0.23 a & 15.37 a & 0.03 a \\  A \(\times\) F & 12.63 a & 0.45 a & 0.24 a & 16.04 a & 0.03 a \\  A \(\times\) D & 8.67 a & 0.48 a & 0.20 a & 9.66 b & 0.02 a \\ \hline \hline \end{tabular}   
\begin{tabular}{c c c c c c} \hline \hline  & **Increment (cm)** & **Increment (cm)** & **Increment (cm)** & **Fresh Weight/Dry Weight/Fruit Weight/Fruit Weight/Fruit Weight/Fruit Weight/Fruit Weight/Fruit Weight/Fruit Weight/Fruit Weight/Fruit Weight/Fruit Weight/FRegardless of the irrigation system used, the presence of _Ailanthus_ increased the K232 and K270 values compared to the control (Table 4), but it did not have any significant impact on peroxide value and acidity. This increase was also observed when full irrigation was applied in the presence of _Ailanthus_. Furthermore, the application of deficit irrigation, regardless of the presence of _Ailanthus_, resulted in a reduction of oil acidity, while no significant differences were detected regarding the peroxide value. Under deficit irrigation (irrespective of _Ailanthus_ presence), the concentration of total flavonoids increased (Table 5). The presence of _Ailanthus_ (irrespective of the irrigation regime employed) led to an increase in the concentration of total o-diphenylons too. The lowest values of total phenolics and total flavonoids were recorded when _Ailanthus_ was absent and full irrigation was applied, with a significant difference from the control under deficit treatment. In contrast, the combination of _Ailanthus_ and deficit irrigation led to the highest concentration of total o-diphenylons. The highest values of all three antioxidant capacity assays (DPPH, FRAP, ABTS) were detected when deficit irrigation was applied in the absence of _Ailanthus_.