## 3 Results
### Field Experiments on Vineyards
#### 3.2.2 Evolution of the Phenolic Composition in Grapes during Ripening Period  
Each group of polyphenol families is directly responsible for the important characteristics of specific grape varieties and their products [44]. The polyphenol compositions at different harvest dates were determined by HPLC-DAD analysis and the results are shown graphically for the main polyphenol families in Figures 3-5. Figure 4: Total flavonoids in grapes during the ripening period. Abbreviations: MeJA: methyl1 jasmonate; Nano-MeJA: methyl jasmonate adsorbed on amorphous calcium phosphate; Ap-MeJA: methyl jasmonate supported on crsailimum calcium phosphate. * Indicates significant differences among treatments according to [PERSON]’s test (\(p<0.05\)). Figure 3: Anthocyanins in grapes during the ripening period. ((**A**) total anthocyanins; (**B**) acylated anthocyanins; (**C**) acetates anthocyanins; (**D**) coumarates anthocyanins.) Abbreviations: MeJA: methyl jasmonate; Nano-MeJA: methyl jasmonate adsorbed on amorphous calcium phosphate; Ap-MeJA: methyl jasmonate adsorbed on crystalline apatite nanoparticles. * Indicates significant differences among treatments according to [PERSON]’s test (\(p<0.05\)). Evolution of Anthocyanins during Ripening Period  
The results for the evolution of total anthocyanins in Monastrell grapes in skin extracts of treated and untreated grapes are shown in Figure 3 (numerical data can be seen in ST2 of the Supplementary Materials). The accumulation of anthocyanins starts at veraison and reaches a maximum around harvest time [45], and they are the main pigments responsible for the colour of the grapes and wines. Regarding total anthocyanins (Figure 3A), the treated grapes obtained the highest concentrations of these compounds at harvest, increasing by 33% when MeJA was applied in a conventional way, and 11% and 12% when applied as Nano-MeJA or as Ap-MeJA, respectively. In this regard, it is worth noting that when we applied Nano-MeJA or Ap-MeJA, the concentration of MeJA used was 10 times lower than when applied in a conventional way, and yet we still managed to increase the concentration of anthocyanin at harvest. These results can be explained by the fact that during maturation, MeJA increases the level of secondary metabolites in grapes, specifically by triggering the biosynthesis of anthocyanins [44]. Several authors have found how MeJA treatments increased anthocyanin levels at harvest for different grape varieties, such as Monastrell, by 25% [24], 29% [46] or 44% (for Garnacha). [47]. Likewise, a study during ripening by [PERSON] et al. [26] revealed how Monastrell grapes treated with MeJA and benzothiadiazol (BTH) showed higher anthocyanin levels than control grapes at the fourth sampling date during ripening, and these differences were maintained until harvest. As we can see, the MeJA and Nano-MeJA treatments obtained higher anthocyanin concentrations from the beginning of the maturation period until harvest. However, at the end of the maturation period the grapes treated with Ap-MeJA also had increased  
Figure 5: (**A**) Total skin proanthocyanidins in grapes during ripening period. (**B**) % epigallocatechin during ripening period. (**C**) mDP in skins during ripening period. (**D**) % galloylation in skins during ripening period. Abbreviations: MeJA: methyl jasmonate; Nano-MeJA: methyl jasmonate adsorbed on amorphous calcium phosphate; Ap-MeJA: methyl jasmonate adsorbed on crystalline apatite nanoparticles. * Indicates significant differences among treatments according to [PERSON]’s test (\(p<0.05\)). anthocyanin concentration compared to the control, although during all the previous samplings they obtained the lowest concentration of anthocyanin.