## 3 Results
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Experimental Treatment**} & \multicolumn{3}{c}{**Leaf Colorimetric Parameters**} \\  & **L* & a* & b* \\ \hline
**Cultivar (Cv)** & & & \\ Mars & 41.0 a & \(-\)14.9 & 22.0 \\ Naples & 41.4 a & \(-\)14.6 & 21.9 \\ Tricia & 41.0 a & \(-\)14.9 & 22.1 \\ Venice & 38.6 b & \(-\)14.7 & 22.8 \\ Olivetta & 40.9 a & \(-\)14.9 & 22.1 \\  & & n.s. & n.s. \\ \hline
**Biostimulant formulation (B)** & & & \\ Control & 38.7 b & \(-\)14.7 & 22.6 \\ _Cystoseira tamariscifolia_ & 39.7 b & \(-\)14.8 & 22.7 \\ Protein hydrolysate & 44.0 a & \(-\)14.9 & 21.7 \\ _Spirulina platensis_ & 40.0 b & \(-\)14.8 & 21.8 \\  & & n.s. & n.s. \\ \hline
**Crop cycle (Cy)** & & & \\ Autumn & 40.6 & \(-\)14.8 & 22.2 \\ Autumn & 40.6 & \(-\)14.8 & 22.2 \\ Winter & 40.6 & \(-\)14.8 & 22.2 \\  & n.s. & n.s. & n.s. \\ \hline
**Interaction** & & & \\ \hline Cv \(\times\) B & n.s. & n.s. & n.s. \\ \hline Cv \(\times\) Cy & n.s. & n.s. & n.s. \\ \hline B \(\times\) Cy & n.s. & n.s. & n.s. \\ \hline \hline \end{tabular} n.s. not significant; values followed by different letters are significantly different at \(p<0.05\) (Tukey’s test).  
\end{table} 
Table 1: Colorimetric parameters L, a, and b of rocket leaves as affected by cultivar, biostimulant formulation, and crop cycle. Figure 4: Interaction between biostimulant formulation and crop cycle on dry matter in rocket leaves. The columns represent the average of all cultivars for each biostimulation. Values followed by different letters are significantly different at \(p<0.05\) ([PERSON]’s test). The L* parameter (brightness) was significantly influenced by both cultivar and biostimulant formulation, but not by crop cycle. Indeed, the variety Venice showed the lowest values, whereas no significant differences were recorded between the other cultivars. The protein hydrolysate application increased the L* parameter by 13.6%, 10.7%, and 9.9%, compared to the untreated control, _Cystoseira tamariscifolia_ and _Spirulina platensis_, respectively, which did not significantly differ from each other. The colorimetric parameters \"a\" and \"b\" were not affected by the three experimental factors applied. A significant interaction between cultivar and biostimulant formulation arose on nitrate content (Figure 5). The treatment with _Cystoseira tamariscifolia_ caused the highest nitrate accumulation in rocket leaves, though not different from the untreated control, in the cultivars Mars, Naples, Tricia, and Venice, whereas in Olivetta no significant differences were recorded between the biostimulant formulations and the control. The untreated control attained the highest nitrate content in the cultivar Venice; Olivetta leaves showed the lowest nitrate accumulation under the _Cystoseira tamariscifolia_ supply; protein hydrolysate and _Spirulina platensis_ did not elicit significant differences in nitrate content between the cultivars. A significant interaction arose between cultivar and biostimulant formulation on nitrogen use efficiency (NUE; Figure 6). Compared to the untreated control, the NUE was increased by protein hydrolysate in the cultivars Mars, Naples, Tricia, and Olivetta (by 22.6%, 28.0%, 26.8%, and 22.8%, respectively), and _Spirulina platensis_ in Venice (by 33.3%). The leaves of the variety Naples showed a higher nitrogen use efficiency than Venice upon the application of the protein hydrolysate biostimulant. No significant differences were recorded between the five cultivars examined under the application of _C. tamariscifolia_ and _S. platensis_, as well as in the untreated control. Figure 5: Interaction between cultivar and biostimulant formulation on nitrate content in rocket leaves. Values followed by different letters are significantly different at \(p<0.05\) (Tukey’s test). The contents of malate and citrate in rocket leaves were significantly influenced by the interaction between biostimulant formulation and crop cycle (Table 2).