## 3 Results
### Biofertilizers Improved Date Palm Growth Parameters under Salt Stress
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**NaCl** & **Treatment** & **Leaf Number** & **Plant Height (cm)** \\ \hline \multirow{8}{*}{0 mM} & Control & 5.33 (1.53) a & 33.50 (3.28) b  \\  & Comp & 6.67 (1.15) a & 42.00 (9.16) a \\  & AMF\({}_{1}\) & 7.67 (0.58) a & 41.67 (3.51) a \\  & AMF\({}_{2}\) & 5.33 (1.53) a & 42.63 (1.18) a \\  & PGPR & 5.67 (1.15) a & 46.07 (1.01) a \\  & AMF\({}_{1}\)+Comp & 7.33 (1.15) a & 47.27 (0.64) a \\  & AMF\({}_{2}\)+Comp & 7.00 (1.00) a & 45.67 (1.53) a \\  & PGPR+Comp & 6.67 (0.58) a & 44.17 (0.76) a \\  & PGPR+AMF\({}_{1}\) & 6.33 (0.58) a & 45.93 (0.90) a \\  & PGPR+AMF\({}_{2}\) & 6.00 (1.00) a & 46.97 (0.35) a \\  & PGPR+AMF\({}_{1}\)+Comp & 7.67 (0.58) a & 47.87 (0.81) a \\  & PGPR+AMF\({}_{2}\)+Comp & 6.67 (1.53) a & 48.10 (0.96) a \\ \hline \multirow{8}{*}{120 mM} & Control & 4.00 (1.00) a & 29.00 (1.00) d  \\  & Comp & 4.33 (1.53) a & 31.33 (2.08) c  \\  & AMF\({}_{1}\) & 6.33 (0.58) a & 31.03 (1.55) c  \\  & AMF\({}_{2}\) & 4.67 (0.58) a & 32.50 (1.32) c  \\  & PGPR & 5.33 (0.58) a & 30.23 (1.12) c  \\  & AMF\({}_{1}\)+Comp & 6.00 (1.00) a & 43.5 (0.50) a  \\  & AMF\({}_{2}\)+Comp & 5.67 (0.58) a & 43.17 (0.76) a  \\  & PGPR+Comp & 5.00 (1.00) a & 40.50 (0.50) b  \\  & PGPR+AMF\({}_{1}\) & 6.00 (1.00) a & 40.20 (1.25) b  \\  & PGPR+AMF\({}_{2}\) & 5.67 (0.58) a & 43.50 (2.18) a  \\  & PGPR+AMF\({}_{1}\)+Comp & 6.33 (1.00) a & 44.50 (0.50) a  \\  & PGPR+AMF\({}_{2}\)+Comp & 5.33 (0.58) a & 43.83 (0.76) a  \\ \hline \multirow{8}{*}{240 mM} & Control & 3.33 (0.58) b  \\  & Comp & 3.33 (0.58) b  & 29.33 (1.53) c  \\  & AMF\({}_{1}\) & 4.67 (0.58) a, b  & 28.17 (0.76) c  \\  & AMF\({}_{2}\) & 3.33 (0.58) b  & 27.47 (0.61) c  \\  & PGPR & 4.67 (0.58) a, b  & 25.37 (2.95) d, e  \\  & AMF\({}_{1}\)+Comp & 5.67 (1.15) a, b  & 34.23 (0.75) b  \\  & AMF\({}_{2}\)+Comp & 5.33 (0.58) a  & 34.60 (0.79) b  \\  & PGPR+Comp & 4.33 (0.58) a  & 36.63 (0.71) b  \\  & PGPR+AMF\({}_{1}\) & 4.67 (0.58) a, b  & 36.63 (0.71) b  \\  & PGPR+AMF\({}_{1}\) & 4.67 (0.58) a, b  & 36.77 (1.75) b  \\  & PGPR+AMF\({}_{2}\) & 4.67 (0.58) a, b  & 36.37 (1.10) b  \\  & PGPR+AMF\({}_{1}\)+Comp & 6.00 (1.00) a  & 42.07 (0.90) a  \\  & PGPR+AMF\({}_{2}\)+Comp & 4.67 (0.58) a, b  & 41.36 (0.78) a  \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Effects of biofertilizers on growth parameters of date palm vitroplants under different salt (NaCl) stress levels, 0, 120 and 240 mM. Accordingly, the root dry weight (RDW) was also significantly increased by biofertilizer treatment under all salt stress levels (\(p<0.001\), F = 114.25). Under non-stressed conditions, the tripartite combination PGPR+AMF\({}_{2}\)+Comp presented the highest improvement of 187% over the control. At 120 mM, the highest record was obtained by the application of the bipartite combination AMF\({}_{2}\)+Comp, which increased RDW by 161% compared to the control. In addition, under the highest salt stress, only the bipartite AMF\({}_{2}\)+Comp (155%) and tripartite PGPR+AMF\({}_{1}\)+Comp (139%) treatments significantly increased the RDW compared to the salt-stressed control. Biofertilizers Promoted Date Palm Chlorophyll Fluorescence, Gas Exchange and Leaf Water Potential under Salt Stress  
Chlorophyll fluorescence was not affected by biofertilizer application (data not presented). In contrast, gas exchange (gs) and leaf water potential (leaf \(\Psi\)) were both affected by biofertilizer application under all salinity levels (Table 3). Figure 3 showed that the application of biofertilizers improved the gs (\(p<0.001\), F = 11.22), except for the stressed plants treated by Comp, AMF\({}_{1}\), AMF\({}_{2}\), PGPR and AMF\({}_{1}\)+Comp, which presented no significant difference compared to stress controls. A high enhancement of 50% was recorded by the tripartite combination PGPR+AMF2+Comp. Under both  
Figure 2: Effects of salt stress and biofertilizers on shoot dry weight (SDW) and root dry weight (RDW) of date palm vitroplants.