## 3 Results
In order to estimate antioxidant capacities in apple plants, both the 2,2-diphenyl1-1-picryl hydrazil (DPPH) method [62] and the ferric reducing antioxidant potential (FRAP) method [63] were used. The first method showed that there were statistically significant differences in antioxidant capacity among the treatments (Figure 2a). In the subtreatments where no NaCl was administered to the plants (I), no significant differences were recorded in the antioxidant capacity between the various treatments, and also no differences were found in the sub-treatments where only NaCl was administered (II). Nevertheless, the antioxidant capacity of plants was lower in normal conditions than when the irrigation with salt took place in all substrate additives, while in the case of zeolite the aforementioned parameter reached the highest value. However, the application of seaweed extract under saline conditions overturned the previous picture, leading to the statistically significantly lowest antioxidant capacities in zeolite and in the EM treatment. \begin{table}
\begin{tabular}{c c c c c} \hline
**Treatments–Substrate** & **Sub-Treatments** & **Proline (\(\mu\)mol/g FW)** & **Carbohydrates (\(\mu\)mol/g FW)** & **Carotenoids (mg/g FW)** \\ \hline Control & I & 2.09 \(\pm\) 0.82 bc & 59.97 \(\pm\) 12.2 a & 564.13 \(\pm\) 78.32 bcd \\  & II & 0.75 \(\pm\) 0.27 c & 69.20 \(\pm\) 7.54 a & 687.04 \(\pm\) 84.71 a–d \\  & III & 1.07 \(\pm\) 0.70 c & 43.56 \(\pm\) 10.74 a & 687.78 \(\pm\) 21.53 a–d \\  & IV & 1.65 \(\pm\) 0.55 bc & 57.66 \(\pm\) 12.26 a & 823.88 \(\pm\) 31.00 ab \\ \hline Zeolite & I & 1.72 \(\pm\) 0.45 bc & 71.97 \(\pm\) 10.70 a & 847.60 \(\pm\) 100.35 a \\  & II & 2.44 \(\pm\) 0.86 bc & 56.69 \(\pm\) 12.73 a & 543.32 \(\pm\) 79.53 cd \\  & III & 1.33 \(\pm\) 0.42 c & 39.45 \(\pm\) 6.04 a & 524.13 \(\pm\) 24.62 cd \\  & IV & 1.09 \(\pm\) 0.20 c & 59.21 \(\pm\) 6.12 a & 736.79 \(\pm\) 6.67 abc \\ \hline EM & I & 1.10 \(\pm\) 0.39 c & 64.88 \(\pm\) 2.96 a & 673.78 \(\pm\) 47.16 a–d \\  & II & 5.63 \(\pm\) 0.54 a & 65.88 \(\pm\) 12.76 a & 681.11 \(\pm\) 18.51 a–d \\  & III & 4.16 \(\pm\) 0.63 ab & 48.34 \(\pm\) 2.34 a & 430.80 \(\pm\) 24.74 d \\  & IV & 1.76 \(\pm\) 0.30 bc & 55.48 \(\pm\) 11.83 a & 602.32 \(\pm\) 3.56 a–d \\ \hline \end{tabular} All the values are averages of three replications \(\pm\) standard error. The different letters in the same column show statistically significant differences among the twelve subtreatments according to the Tukey’s test (\(p\leq\) 0.05) with the larger values corresponding to the letter “a”. I: no NaCl, II: NaCl 50 mM, III: NaCl 50 mM + seaweed extract spraying, IV: NaCl 50 mM + ceramic powder spraying. EM treatment included compost addition.  
\end{table} 
Table 2: Proline, carbohydrate, and carotenoid concentration in leaves of the apple plants. Figure 2: (**a**) DDPH, (**b**) FRAP, (**c**) phenolic compounds, and (**d**) flavonoid concentration in leaves of the apple plants. All the values are averages of three replications \(\pm\) standard error. The different letters in the same column show statistically significant differences among the nine subtreatments, according to the Tukey test (\(p\leq 0.05\)) with the larger values corresponding to the letter “a”. I. no NaCl, II: NaCl 50 mM, III: NaCl 50 mM + seaweed extract spraying. EM treatment included compost addition. The antioxidant capacity did not demonstrate any significant fluctuations when it was assessed with the ferric reducing antioxidant potential (FRAP) method. The highest value was recorded in plants that were grown in zeolite under saline conditions (Figure 2b). Furthermore, no significant variations were observed in the concentration of phenolic compounds in the leaves among the treatments in this study (Figure 2c). The phenolic concentration ranged at the same level in all substrate additives without NaCl (I). Nonetheless, the addition of salt (II) brought about a decline in phenols in the control treatment, while a rise in these compounds occurred in the zeolite treatment.