## 2 Materials and Methods
### Leaf Functionality and Tree Water Relations  
Three plants similar in canopy size and potential crop load were selected for each treatment. At fruit cell division, pit hardening, fruit cell expansion and close to the harvest stages, leaf net photosynthesis (Pn, \(\mu\)mol m\({}^{-2}\) s\({}^{-1}\)), stomatal conductance (gs, mol m\({}^{-2}\) s\({}^{-1}\)) and transpiration (Tr, mol m\({}^{-2}\) s\({}^{-1}\)) were measured on well-exposed leaves placed on the east and west side of the canopy, 4 times during the day (9.00-17.00 h), with an open circuit infrared gas analyzer fitted with an LED light source (Li-COR 6400 XT, LI-COR, Lincoln, Nebraska, USA). At each time of the day and canopy side, light intensity was maintained constant across the 4 treatments, setting the LED light source at the natural irradiance experienced by the leaf immediately before the measurement. The values obtained on the west and east side of the canopy were averaged for each tree. At the same time of measure, stem water potential  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Date**} & \multirow{2}{*}{**Treatment**} & **N** & **P** & **pH** & **EC** & **TOC** \\  & & **(g kg\({}^{-1}\))** & **(mg kg\({}^{-1}\))** & & & **(dS m\({}^{-1}\))** & **(\%)** \\ \hline \multirow{8}{*}{14/04/2015} & T & 1.06 & 34.40 & 8.43 & 0.17 & 1.05 & a \\  & M & 1.00 & 28.32 & 8.38 & 0.17 & 0.98 & b \\  & F & 0.98 & 44.70 & 8.42 & 0.17 & 1.03 & a \\  & S & 1.20 & 41.48 & 8.40 & 0.14 & 1.05 & a \\ \cline{2-7}  & _F-value_ & _3.08_ & _1.45_ & _0.47_ & _4.12_ & _10.72_ & \\  & _p-value_ & _0.129_ & _0.334_ & _0.715_ & _0.081_ & _0.013_ & \\ \hline \multirow{8}{*}{24/09/2015} & T & 1.21 & 42.05 & 8.33 & 0.18 & 1.22 & \\  & M & 1.15 & 35.87 & 8.26 & 0.18 & 1.16 & \\  & F & 1.00 & 53.00 & 8.32 & 0.19 & 1.18 & \\  & S & 1.17 & 51.46 & 8.21 & 0.20 & 1.22 & \\ \cline{2-7}  & _F-value_ & _1.30_ & _1.49_ & _0.94_ & _0.05_ & _0.95_ & \\  & _p-value_ & _0.372_ & _0.325_ & _0.489_ & _0.981_ & _0.484_ & \\ \hline \multirow{8}{*}{16/12/2016} & T & 0.68 & 37.97 & ab & 8.31 & 0.19 & 1.11 & a \\  & M & 0.66 & 39.83 & ab & 8.38 & 0.12 & 1.20 & a \\ \cline{1-1}  & F & 0.94 & 52.36 & a & 8.27 & 0.17 & 1.18 & a \\ \cline{1-1}  & S & 0.75 & 27.14 & b & 8.33 & 0.13 & 0.99 & b \\ \cline{1-1} \cline{2-7}  & _F-value_ & _1.07_ & _5.53_ & _0.28_ & _0.43_ & _8.57_ & \\ \cline{1-1}  & _p-value_ & _0.392_ & _0.010_ & _0.838_ & _0.736_ & _0.002_ & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Soil chemical traits at the beginning of the trial (14 April 2015) after the harvest of the first year of the study (24 September 2015) and before the winter pruning of the second year (16 December 2016). Within each date and for each variable, different letters indicate a statistical difference at \(p\leq 0.05\).  
(Vs, MPa) was measured on the same trees belonging to the 4 treatments according to [37]. Pn and Tr, collected during the day, were integrated [38], providing the specific amount of CO2 (\(\Sigma\)Pn, mol m\({}^{-2}\)) and water (\(\Sigma\)Tr, mol m\({}^{-2}\)) fixed and transpired by a square meter of leaf during the time of measure. To take into account the amount of energy used by trees to raise water from the soil during the time of measure, the water stress integral (S\({}_{\Psi}\), GPa) was calculated as the difference between the integral by time of stem water potential and the integral by time of the minimum stem water potential measured in the same time range [39; 40].