(1) Background: Spring frost damage is a common phenomenon that occurs in Southern Chile that considerably affects vine productivity and grape quality. (2) Methods: A field trial was conducted in order to study vine phenology and berry physicochemical parameters in Chardonnay, Sauvignon Blanc and Pinot Noir ungrafted and grafted (onto 101-14 Mgt rootstock) grapevines after a spring frost. This event killed the totality of primary bud shoots when the vines reached the phenological stage of unfolded leaves. (3) Results: From budburst, to flowering of secondary bud shoots, ungrafted Sauvignon Blanc grapevines presented an advanced phenology, whereas 101-14 Mgt rootstock tended to advance the maturity of Pinot Noir grapevines from flowering to ripening of berries. At harvest, berries from secondary buds of vines grafted onto 101-14 Mgt rootstock showed higher soluble solids than the ones from ungrafted Chardonnay and Sauvignon Blanc vines. High total phenolic content was found in berries from secondary buds of the grafted vines, compared to the ones from the ungrafted vines. Berry soluble solids variability tended to statistically decrease toward harvest in the studied plant materials, and the maximum coefficient of variation for soluble solids, berry weight, berry firmness and berry size reached 9.5%, 25.9%, 18.6% and 8.9%, respectively. (4) Conclusions: These preliminary results may be interesting for the Southern Chilean viticulturists since it seems that 101-14 Mgt rootstock could affect phenology and grape berry maturity of grapevines established in the Cautín Valley after spring frost damage.

Plastic covers have been used to prevent environmental constraints negatively affecting sweet cherry production in Southern Chile. However, less information is available on agronomic practices and their effects on fruit quality in sweet cherry covered orchards. Thus, in this study, we evaluated the impact of fruit load regulation on cherries’ antioxidant-related parameters and the quality and condition at harvest and postharvest in sweet cherry (Prunus avium) cv. Regina that was cultivated under a plastic cover in Southern Chile. For this, four fruit load treatments were manually applied—(i) 100% fruit load (the control), (ii) 80% fruit load, (iii) 60% fruit load, and (iv) 40% fruit load—in a commercial sweet cherry orchard for two seasons (2021/2022 and 2022/2023). The results revealed that the yield and fruit load were not significantly different between the treatments. Interestingly, the 60% and 40% fruit loads increased the fresh weight, fruit size, and firmness (20.3%) compared to the control (the 100% fruit load) during both seasons. Likewise, the 60% and 40% fruit load treatments exhibited the highest fruit size distribution of 30 mm, while the 100 and 80% fruit load treatments showed the highest fruit distribution with fruit sizes between 28 mm and 24 mm. The total soluble solids (TSSs) did not vary among the fruit load treatments, while a significant increase was found in the titratable acidity (TA) in the 60 and 40% fruit load treatments during both seasons. No significant differences in antioxidant activity (AA) and total phenols (TPHs) among the treatments were observed during both seasons. Overall, the results revealed that the fruit load treatments, mainly 40%, increased the fruit weight and firmness and reduced pitting in fruits by 39.4% at postharvest. Thus, fruit thinning might be an important agronomical practice to regulate fruit load, positively affecting fruit quality at harvest and during postharvest storage in sweet cherry cv. Regina cultivated under a plastic cover. However, more biochemical and molecular studies are needed to elucidate the mechanism involved in this improvement.

Plastic covers protect fruits from cracking caused by pre-harvest rains in sweet cherry orchards; however, they can decrease the quality parameters of cherries, such as firmness, titratable acidity, color, and sugar content. This study evaluated the impact of a reflective ground film used for 21 or 34 DBH (days before harvest) in a commercial sweet cherry orchard (cv. Regina) grown under plastic cover in southern Chile. Our study showed that the exposition of cherry trees to the reflective film increased firmness and total soluble solid (TSS) content in fruits at harvest, homogenizing the concentration of sugars in fruits along the tree canopy. Additionally, using reflective film for 21 DBH increased the proportion of fruits greater than 32 mm in the upper canopy and the quantity of mahogany-colored cherries in the lower canopy, compared to trees un-exposed to the reflective film. Concerning fruit condition defects, the results reveal that using the reflective film increased the incidence of cracking in fruits in both the upper and lower zones of the canopy. Furthermore, we found that the incidence of orange skin and pitting in fruits decreased at post-harvest in trees exposed to the reflective film, but depending on the canopy zones. Moreover, fruits of trees exposed to the film for 34 DBH exhibited a higher incidence of browning pedicel post-harvest. Finally, according to our results, the antioxidant activity increased in fruits exposed to the reflective film for 21 DBH. Therefore, we can conclude that using reflective films on sweet cherry orchards can improve and homogenize the maturity parameters and the antioxidant activity of fruits; however, this practice can negatively impact the condition of fruits post-harvest.