## 3 Results
Indeed, for the untreated control, higher values of malate content were recorded during the autumn-winter crop cycle, followed by the autumn and finally the winter cycle; the brown algae treatment led to higher malate values at the second cycle; under the protein hydrolysate and _Spirulina platensis_ applications, the mentioned organic acid showed a similar trend as in the untreated control. In the autumn-winter cycle, the protein hydrolysate and _Spirulina_ treatments led to higher malate content than the control, whereas in autumn and winter no significant differences were recorded. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Biostimulant Formulation** & **Crop Cycle** & \begin{tabular}{c} **Malate** \\ **(g kg\({}^{-1}\) d.w.)** \\ \end{tabular} & \begin{tabular}{c} **Citrate** \\ **(g kg\({}^{-1}\) d.w.)** \\ \end{tabular} \\ \hline Control & \begin{tabular}{c} Autumn \\ Autumn-winter \\ Winter \\ \end{tabular} & \begin{tabular}{c} 9.1 c \\ 24.2 b \\ 6.1 def \\ \end{tabular} & \begin{tabular}{c} 23.2 a \\ 10.3 ef \\ 15.5 cde \\ \end{tabular} \\ \hline _Cystoseira tamariscifolia_ & \begin{tabular}{c} Autumn \\ Autumn-winter \\ Winter \\ \end{tabular} & \begin{tabular}{c} 8.3 cd \\ 25.6 ab \\ 6.5 cdef \\ \end{tabular} & \begin{tabular}{c} 20.7 abc \\ 10.2 ef \\ 17.8 bcd \\ \end{tabular} \\ \hline Protein hydrolysate & \begin{tabular}{c} Autumn \\ Autumn-winter \\ Winter \\ \end{tabular} & \begin{tabular}{c} 7.5 cd \\ 27.3 a \\ 4.6 ef \\ \end{tabular} & \begin{tabular}{c} 22.2 ab \\ 8.8 f \\ 13.0 def \\ \end{tabular} \\ \hline _Spirulina platensis_ & \begin{tabular}{c} Autumn \\ Autumn-winter \\ Winter \\ \end{tabular} & \
\begin{tabular}{c} 6.8 cde \\ 28.1 a \\ 4.0 f \\ \end{tabular} &
\begin{tabular}{c} 16.4 cd \\ 10.3 ef \\ 11.0 ef \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Interaction between biostimulant formulation and crop cycle on malate and citrate contents in rocket leaves. Figure 6: Interaction between cultivar and biostimulant formulation on nitrogen use efficiency in rocket. Values followed by different letters are significantly different at \(p<0.05\) (Tukey’s test). The citrate content (Table 2) in the untreated control, and in plants supplied with protein hydrolysate and _Spirulina_, was higher in autumn, whereas under _Cystoseira tamariscifolia_ application it was significantly lower during the second crop cycle, compared to the other two cycles. Moreover, in the same season the citrate content was lower upon _Spirulina_ treatment, compared to the other biostimulants and the untreated control; in winter _Cystoseira tamariscifolia_ resulted in higher citrate accumulation than _Spirulina plantensis_; no significant differences between the biostimulant formulations were recorded in autumn-winter. The hydrophilic antioxidant activity (HAA) was significantly influenced by cultivar and biostimulant formulation (Table 3), whereas only the latter experimental factor showed a significant effect on lipophilic antioxidant activity (LAA). Particularly, the variety Naples showed higher HAA values (0.24 mmol ascorbic acid eq. 100 g\({}^{-1}\) f.w.) compared to the other cultivars, which did not differ from each other (0.09 mmol ascorbic acid eq. 100 g\({}^{-1}\) f.w., as an average). Regarding the applied biostimulants, _Spirulina platensis_ elicited the highest HAA values in rocket leaves (0.2 mmol ascorbic acid eq. 100 g\({}^{-1}\) f.w. ), whereas no significant differences arose between the other treatments. The interaction between cultivar and biostimulant formulation was significant on the lipophilic antioxidant activity (LAA; Figure 7). Rocket leaves in the untreated control showed significantly higher LAA values, compared to the treatment with _Cystoseira tamariscifolia_, in the varieties Mars and Naples (by 19.1% and 16.7%, respectively), while no significant differences arose between the three biostimulant formulations. The untreated control leaves also showed higher values than