## 4 Discussion
### Yield, Quality, Antioxidants, and Mineral Composition
The significant enhancement of HAA under the _Spiulina platensis_ application confirms the enhanced antioxidant capacity recorded in wild rocket treated with microalgae-based biostimulants by [PERSON] et al. [16]. The contrasting effects of biostimulants on HAA and LAA in the present study highlight their different impact on the antioxidant pathways, as previously reported by [PERSON] et al. [38] in wall rocket. The reduction in LAA following _Spiulina platensis_ treatment, particularly in the cultivars Olivetta and Tricia, suggests that microalgae-derived compounds may prioritize the mechanisms related to water-soluble antioxidants over the lipid-soluble ones, potentially through selective gene expression modulation [22]. The variety-dependent reactions to biostimulant applications, in terms of LAA, reflect previous similar findings in perennial wall rocket [26] and, particularly, the higher values recorded in untreated controls in some cultivars are consistent with the observations of [PERSON] and [PERSON] [39]. In our research, the lack of significant antioxidant differences between the crop cycles contrasts with previous investigations on wild rocket [16], and this discrepancy may be due to variations in environmental conditions or cultivation systems [40]. The distinct antioxidant profiles induced by different biostimulants suggest the related diversity in biochemical mechanisms, according to the composition of the applied formulation: _Cystoseira tamariscifolia_ is rich in polysaccharides and phytohormones [17], whereas protein hydrolyses have a high content of nitrogen-based compounds that enhance protein synthesis [41]. The interaction between cultivar and biostimulant formulation on nitrate accumulation revealed differential responses of the five wild rocket varieties compared. Venice showed the most pronounced reaction to biostimulant application, with both protein hydrolysate and _Spirulina platensis_ treatments significantly reducing NO\({}_{3}\) content, compared to the untreated control. This genotype-dependent response agrees with previous research: a 10.6% nitrate content reduction in wild rocket leaves was recorded following biostimulant treatment [18], and an effect on nitrate content in greenhouse-grown spinach was related to the biostimulant formulation used [21]. The contrasting responses of cultivars can be attributed to genotypic variations in nitrogen metabolism pathways, which in lettuce cultivars primarily stem from the change in nitrate uptake mechanisms rather than from differences in nitrate reduction capacity [13]. [PERSON] et al. [11] reported similar variation in nitrate accumulation in lettuce cultivars, some of which maintained lower nitrate levels regardless of growing conditions. Interestingly, in the cultivars Mars and Tricia only the application of protein hydrolysate elicited a tendency toward lower nitrate content, compared to _Cystoseira tamarsic-folia_ treatment, though not significantly different than the untreated control. The latter outcome is consistent with the findings by [PERSON] et al. [16], who demonstrated a 24% decrease in nitrate content in wild rocket leaves upon the application of protein hydrolysates derived from Fabaceae tissues, like in our study, despite remarkable variations between the genotypes. No significant differences in nitrate accumulation were observed in the variety Olivetta under the biostimulant treatments, suggesting a genetic stability of nitrate metabolism regardless of biostimulation formulation, as also reported by [PERSON] et al. [12] in lettuce cultivars with rather stable nitrate content under different growing seasons and conditions. The importance of selecting appropriate biostimulant-genotype combinations to effectively prevent nitrate accumulation in wild rocket was supported by [PERSON] [9], who emphasized the need for integrated strategies to manage nitrate content in leafy vegetables, particularly the nitrate hyperaccumulator species like rocket.