## 3 Results
### Field Experiments on Vineyards
#### 3.2.2 Evolution of the Phenolic Composition in Grapes during Ripening Period
The delayed impact of Ap-MeJA treatment on anthocyanin concentrations and berry weight (Figure 2D) could be explained by the lower % of MeJA content in Ap nanoparticles (Ap-MeJA, 2.8 wt.%) compared to ACP nanoparticles (Nano-MeJA, 6.2 wt.%) [48] and thus the need for a higher Ap-MeJA nanoparticle uptake, at least twice that of Nano-MeJA, to provide similar MeJA content to the Nano-MeJA treatment. In fact, Ap-MeJA treatments required 7.8 g of nanoparticles per litre for the application of 1 mM of MeJA, while Nano-MeJA treatment involved 3.6 g of nanoparticles per litre for the same MeJA concentration. Regarding acylated anthocyanins (Figure 3B), as occurred with total anthocyanins, these compounds increased during the ripening period until harvest time. Acylation is one of the most common modifications of plant phenolics, including anthocyanins, resulting in a significantly large structural diversity of anthocyanins from the addition of aromatic and/or aliphatic constituents linked to the C6\" positions of the glucosyl groups [49]. The amount of acylated anthocyanins is largely influenced by the grape variety and may be absent from some varieties such as Pinot Noir [3]. Regarding treatments, all treatments applied improved the acylated anthocyanin concentrations. It was observed that conventional MeJA treatment had the greatest influence on acylated anthocyanins, promoting an increase of 33% compared to control grapes at harvest time, as occurred with total anthocyanins. In the cases of nanoparticulate treatments, the increases were 22% for Nano-MeJA and 23% for Ap-MeJA. In another study, [PERSON] et al. [23] showed how MeJA enhanced all forms of acylated anthocyanins in Tempranillo grapes in 2016, although they did not find the same results in previous seasons. In addition, [PERSON] et al. [50] also showed how MeJA increased the acylated forms in Tempranillo grapes, although these differences were not found when MeJA was applied together with phenyl alanine. During the evolution observed in the ripening period, in general, all treatments increased the concentration of acylated anthocyanins in this period when compared to the control grapes. The high concentration reached in the fourth sampling by the grapes treated with MeJA is noteworthy. In the fifth sampling, all samples appeared to be equal, and it is from this moment until harvest when the grapes treated with MeJA and those treated with Nano-MeJA obtained the highest concentrations of acylated anthocyanins, although these differences were not statistical significant. Regarding acetates (Figure 3C), again, all treatments applied boosted acetate anthocyanins, with MeJA applied in the conventional way increasing it by the most (41%) compared to control grapes. In the case of nanoparticles, the increases were 13% in Nano-MeJA and 22% in Ap-MeJA. The possible explanation for the different increases produced using nanoparticles could be due to their different structure and morphology; the first is spherical and the second is elongated, as it has been specified in Section 3.1 of this work. As can be seen in Figure 3C, the increase in these compounds in MeJA-treated grapes was shown from the beginning of the ripening period until harvest, obtaining the highest concentration. Regarding the rest of the treatments, this increase was evident from the third sample until harvest when compared to control grapes. Finally, coumarates (Figure 3D) were also increased using the different MeJA treatments, in this case the highest increase was caused by Nano-MeJA (20%), followed by MeJA applied in a conventional way (17%) and then Ap-MeJA (7%) at harvest time. For these compounds, again the difference in the structure and morphology of the nanoparticles influenced the obtained results. During the ripening period a variability in the results was observed for both the control grapes and the applied treatments. In summary, in all cases, acylated, acetate and coumarate anthocyanins increased with MeJA treatments.