Bioscience Evidence 2026, Vol.16, No.4, 221-234 http://bioscipublisher.com/index.php/be 223 In an early-season peach orchard in southern Tunisia, both continuous deficit irrigation at 50% ETc (DI) and partial root-zone drying at 50% ETc (PRD50) produced positive results. These treatments increased fruit dry matter and firmness. The DI treatment achieved the highest SSC of 14.3°Brix, while reducing some organic acids and increasing several phenolic compounds, anthocyanins, and mineral elements. Moderate water stress can therefore be an effective strategy for saving irrigation water and improving commercial fruit quality in dry regions. However, its long-term effects still require multi-year evaluation, and attention should be given to the risks of soil salinization and tree decline caused by poor-quality irrigation water (Toumi et al., 2022). In a late-season peach orchard under semi-arid conditions, reflective ground covers reduced water loss and maintained or even increased net photosynthesis, yield, and fruit size, although only about 50% of the normal irrigation amount was applied (Losciale et al., 2020). 2.4 Nutrient management and fertilization Nitrogen, phosphorus, potassium, and mineral elements such as Ca, B, Fe, and Mn determine the nutritional status of peach trees. They also influence fruit quality by affecting fruit development, carbohydrate accumulation, and organic acid metabolism. Nitrogen deficiency reduces flower bud quality, weakens root growth, and limits water and nutrient uptake. In contrast, excessive nitrogen promotes excessive vegetative growth, increases pruning costs, reduces fruit quality, and raises the risk of disease. Therefore, nitrogen management should always be balanced with other nutrients and adapted to local growing conditions. In commercial peach orchards located in warm regions, an appropriate split application of N, P, and K improved both yield and fruit quality. Higher nitrogen supply during the S2 growth stage favored higher yield, while higher nitrogen and potassium supply during the S3 and S4 stages was generally associated with greater fruit weight, larger fruit diameter, and higher SSC. In contrast, phosphorus supply was negatively correlated with total sugar content (Maatallah et al., 2024). A soil mineral prediction model further showed that available B, Ca, N, and K had the greatest influence on fruit weight, whereas available Fe, K, B, and Ca were the most important factors affecting SSC. These results suggest that precision fertilization should focus on coordinated management of multiple nutrients rather than single-element application (Sun et al., 2022). 2.5 Bagging cultivation and fruit protection measures Fruit protection practices, including ground cover, fruit bagging, and protective facilities, influence peach fruit quality by changing the orchard microclimate. Regarding ground management, clean cultivation often reduces soil fertility and damages the orchard ecosystem, which can indirectly decrease both yield and fruit quality. In contrast, grass cover, especially hairy vetch (Vicia villosa), improves soil nitrogen availability and microbial diversity, promotes tree growth, increases fruit sugar content and the sugar-to-acid ratio, and reduces organic acid levels (Guo et al., 2024). 3 Orchard Management and Peach Fruit Quality Development 3.1 Light regulation and fruit coloration Light management plays a key role in peach appearance, especially peel redness and color uniformity. The main purpose of an ideal tree architecture is not simply to increase total light interception but also to improve light distribution within the canopy, producing fruit with more uniform and higher quality. In 'Xiahui 8' peach, the open-center canopy provided better light distribution and greater light interception than the Y-shaped canopy, resulting in higher fruit weight, soluble solids, dry matter, firmness, yield, and economic return. Fruits located in the upper canopy usually showed better coloration and higher soluble solids, and relative light intensity between 30% and 90% was positively correlated with fruit size, skin color, and the sugar-to-acid ratio (Zhen et al., 2025). Under planar training systems, fruit color, soluble solids, and titratable acidity showed stronger metabolic relationships, suggesting that improved light conditions not only change fruit appearance but also reshape metabolic coordination during ripening. In rain-shelter orchards, light quality is also important. Long-term low light reduces tree growth, yield, and fruit quality. Neutral light-filtering films help maintain leaf photosynthesis and overall fruit quality, whereas yellow films increase fruit size but reduce skin coloration and internal quality (Zhang et al., 2018).
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