## 4 Discussion
With respect to nutrient (N) recipes, the impact on total fruit yield was not significant. However, N1 and N2 were found to have better effects compared with other recipes, with LSD of 1.167 and 1.190 kg m\({}^{-2}\) for the first and second seasons, respectively. These results showed that all studied tomato cultivars could be grown successfully under hydroponic systems using irrigation water with salt concentration up to 6.0 dS m\({}^{-1}\) in combination with the N1/N2 recipe without affecting total fruit yield. The results shown in Tables 6 and 7 indicate that grafted plants tolerated salinity stress better than non-grafted plants, as evidenced by the higher vegetative growth and yield under high-salinity conditions (i.e., -9.0 dS m\({}^{-1}\)). The increase in WUE was clearly observed in the grafted cultivars, whose WUE under the low-salinity (S1) conditions was greater by 42-47.0% (for non-grafted plants) and 50-55.1% (for grafted plants) compared with those under the high-salinity conditions (S3). Similar results were reported by [PERSON] et al. [42], who found that the difference in the WUE of tomato cultivars with respect to salinity treatments ranged between 2 and 15 dS m\({}^{-1}\), which was less evident than in the present study. Another study [43] also confirmed that irrigation of tomato plants with moderate saline water could be more efficient. Moreover, the nutrient recipe N2 was superior under salinity stress compared with the N3 and N4 recipes due to its higher performance in terms of vegetative growth and yield parameters. Also, higher WUE values were recorded in Maxifort-grafted tomato plants compared with non-grafted plants under the low-salinity level (S1). Moreover, non-grafted plants grown under the S1 treatment showed the lowest plant growth and yield values (Table 4). These results support the results of [PERSON] et al. [44], who found that grafting tomato plants onto an appropriate rootstock reduces crop yield losses under salinity stress. Grafting Valouro-RZ and Ghandowra-F1 cultivars onto Maxifort significantly improved their growth and yield parameters (Table 8). This is because plants grafted onto a suitable rootstock are able to absorb more water and nutrients from the root zone than non-grafted plants due to their robust root structure, which increases the contents of endogenous plant hormones and, thus, the rate of photosynthesis, which in turn enhances plant growth and fruit development [30; 31]. Distinct variations in plant growth and fruit yield were observed among the studied tomato cultivars due to the applied salinity treatments. The re \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multicolumn{5}{c}{**Pr \textgreater{} F**} \\ \cline{2-6}  & **Yield** & **WUE** & **Plant Height** & **Stem Diameter** & **Leaf Area** \\ \hline Salinity (S) & \textless{}0.0001 & \textless{}0.0001 & \textless{}0.0001 & \textless{}0.0001 & \textless{}0.0001 \\ Nutrient (N) & 0.045 & 0.045 & 0.085 & 0.335 & 0.333 \\ Grafting (G) & \textless{}0.0001 & \textless{}0.0001 & \textless{}0.0001 & \textless{}0.0001 & \textless{}0.0001 \\ \(\text{S}^{\text{N}}\) & \textless{}0.0001 & \textless{}0.0001 & 0.040 & 0.031 & 0.001 \\ \(\text{S}^{\text{*G}}\) & 0.163 & 0.163 & 0.168 & 0.504 & 0.086 \\ \(\text{N}^{\text{*G}}\) & 0.705 & 0.705 & 0.595 & 0.260 & 0.462 \\ \(\text{S}^{\text{*N}}\text{S}^{\text{*G}}\) & 0.001 & 0.001 & 0.849 & 0.963 & 0.036 \\ \(\text{R}^{2}\) & 0.962 & 0.962 & 0.901 & 0.876 & 0.896 \\ Coeff. Var. & 8.49 & 8.49 & 7.38 & 10.05 & 9.78 \\ RMSE & 1.98 & 2.25 & 16.13 & 1.23 & 1.39 \\ Mean & 23.36 & 26.48 & 218.46 & 12.23 & 14.25 \\ LSD & 1.167 & 1.32 & 9.48 & 0.72 & 0.82 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Analysis of variation (ANOVA) (mean square) examining agro-morphological traits in tomato plants under different salt stress (S), nutrient (N) recipe, and grafting conditions (season 1). sults showed that Valouro-RZ recorded higher vegetative growth and fruit yield compared with Ghandowra-F1 and Feisty-Red cultivars (Table 3).