## 4 Discussion  
### Yield, Quality, Antioxidants, and Mineral Composition  
The results from the present two-year research demonstrated that the biostimulant effect on wild rocket (_Dipidtaxis tenuifolia_ L.) production is strongly genotype dependent. Protein hydrolysate proved to be the most effective biostimulant for the cultivars Mars, Naples, Tricia, and Olivetta, with remarkable yield increase by approximately 25-26%, compared to the untreated control. The latter outcome is consistent with previous findings [26,27] regarding the positive impact of protein hydrolysate on yield and quality in rocket and other leaf vegetables. The obtained results may be due to enhanced nutrient uptake, photosynthetic activity, and nitrogen metabolism of the mentioned varieties [28,29]. However, the rocket cultivar Venice provided a positive response exclusively to _Spirulina platensis_ application, with a 36.2% yield increase compared to the untreated control, which is in accordance with the reports from other authors [30,31] concerning other crops. In the latter cases, the treatment with _Spirulina_ significantly enhanced growth parameters, photosynthetic pigment concentration, and antioxidant activity, which likely relates to the phytohormes, vitamins, and antioxidant-rich profile of _Spirulina platensis_[32]. The absence of yield response to _Cystoseira tamariscifolia_ supply is in contrast with other studies on leafy greens, though it also depends on the biostimulant concentration and/or genotype,  
Figure 10: Principal component analysis. as previously observed in onion varieties [33]. Protein hydrolysate remarkably augmented yield, as also reported by [PERSON] et al. [26], particularly in the autumn-winter and winter crop cycles (+19.3% and +21.4%, respectively), likely due to the cumulative effects on root development and meristem activity [34]. Protein hydrolysate significantly increased the dry matter content in the cultivars Mars, Tricia, Naples, and Olivetta, confirming its ability to enhance carbon assimilation and structural biomass [26; 27]. _Spiulina_ significantly encouraged dry matter accumulation in Venice, consistent with previous findings about its positive impact on some metabolic pathways without importantly eliciting the carbohydrate accumulation in different genotypes [31]. The latter results indicate that yield response to sequential harvests in wild rocket is significantly influenced by cultivar. Indeed, in our research some varieties exhibited production increase under biostimulant application, progressing from autumn to winter, whereas other cultivars maintained stable yields or selectively reacted to specific formulations, as also observed in other leafy vegetables [26; 27; 34]. Leaf brightness (colorimetric L* value) is a major indicator of visual quality in leafy vegetables and is closely linked to consumer perception of freshness and market value. In our study, the biostimulant application significantly influenced the L* value, while the a* and b* parameters were unaffected. Consistent with our findings, [PERSON] et al. [35] observed that the application of humic-fulvic acids significantly improved leaf brightness and the overall visual appearance in _Amaranthus tricolor_, emphasizing the genotype-dependent biostimulant effect. Similarly, [PERSON] et al. [36] reported a positive influence of brown seaweed-based biostimulants on the L* value of cucumbers. The pigment increase plays an important role in influencing light absorption and reflectance, as recorded in lettuce treated with seaweed and protein hydrolyses [37], and the latter effects may be associated to improved leaf turgor, structural density, and altered epidermal surface properties that enhance light scattering. The higher hydrophilic antioxidant activity (HAA) exhibited by the rocket cultivar Naples is in agreement with previous findings [6] about the genotype-dependent antioxidant responses in leafy vegetables.