# Spatial Variability of Grape Berry Maturation Program at the Molecular Level
## 3 Results and Discussion
### Vineyard Spatial Variability in Vigor and Quality Traits
Compounds associated with unripe berries, such as malic acid that accumulates from fruit set to veraison as a product of photosynthetic activity, were significantly higher in HVC. After veraison, malic acid tends to decline due to berry respiration, which is a process highly accelerated by temperature [35]. Higher concentrations of malic acid in mature HVC berries compared to LVC ones could be the result of greater concentrations reached before veraison or slower depletion, both suggesting a reduced ripening pace possibly related to the higher yield of HVC plants. The cooling effect exerted by largerHVC canopies on cluster microclimate could also have contributed to the slowdown of malic acid degradation. Figure 1: Spatial variability maps. (**a**) Normalized difference vegetation index (NDVI) map generated from a multispectral image. (**b**) Vigor class map interpolated from NDVI values extracted for each block (**c**). Interpolated maps of vine and berry parameters measured at each block. All interpolations followed inverse distance weighting and quantile classification methods. YAN: Yeast assimilable nitrogen. TSS: Total soluble solids. Numbers from 1 to 14 indicate vineyard blocks. Other compounds associated with unripe berries are C\({}_{6}\) aroma compounds responsible for green/grassy sensory attributes. C\({}_{6}\) compounds tend to increase during maturation and decline at late ripening [36]. A high concentration of these compounds in HVC compared to LVC might be due to the more advanced maturation level of the latter at harvest, which agrees with the tight relationship between C\({}_{6}\) abundance and berry developmental stage in Cabernet Sauvignon grapes reported by [PERSON] et al. [25]. The more advanced maturation phase of LVC grapes at harvest can explain the higher concentration of quercetin, anthocyanins, and tannins, which, besides characterizing ripe berries, are also highly susceptible to change in relation to the cluster microclimate [37; 38; 39]. The LVC canopy, which was thinner and with lower \(\Psi_{\text{leaf}}\), might have resulted in greater cluster insolation sun exposure and increased water deficit, which may have promoted the accumulation of these compounds. These results are in line with previous reports on spatial variability in berry composition caused by differences in vigor levels within the vineyard [40; 41; 42; 43]. The bound form of the floral-scented horisoprenoid \(\beta\)-damascenone was more abundant in LVC. Norisoprenoids are formed by carotenoid degradation that occurs from verasion to maturity, and their accumulation becomes significant in the most advanced ripening stages [35]. Since carotenoids are photosynthetic pigments that tend to build on light, the thin vegetation of LVC may have resulted in higher light exposure on developing fruit clusters, promoting carotenoid accumulation and, consequently, higher \(\beta\)-damas cenone concentration in LVC berries. YAN was the berry compositional trait with the greatest intra-vineyard variability (25.49 CV%), and its content was higher in HVC. Nitrogen is the soil nutrient most strictly related to the promotion of plant growth and linked directly with grapevine vigor. It has been reported that an excess of vigor could hinder the YAN content of berries due to a competition between vegetative and reproductive organs for nitrogen [44]. However, in our case, the relationship between YAN and vigor was quite clear, which is consistent with previous observations [45]. For selected parameters, which showed statistically significant differences between the vigor classes (Table 1; Tukey test \(p<0.05\)), spatial variability maps were interpolated (Figure 1b). The maps had comparable patterns among them, which agreed with the NDVI class map pattern, and distinguished the northeast area of the vineyard from the southwest area. LVC was characterized by lower pruning weight and yield per vine, higher concentrations of sugars, \(\beta\)-damascenone, and anthocyanins, and lower concentrations of YAN, C\({}_{6}\) compounds, and malic acid.