Fruit developing in different canopy positions are exposed to distinct light environments that can influence their maturation process and internal quality development. Maturation, a highly regulated process at the molecular level, significantly impacts fruit quality. Our understanding of the true effect of various pre-harvest factors on fruit quality is limited due to poor control of maturity among comparisons in previous studies. Here, an experiment was conducted to assess the true impact of canopy vigor and position (bottom: 0.3–1.2 m and top: 2.1–3.0 m) on ‘Sierra Rich’ (low vigor, LV) and ‘Cresthaven’ (high vigor, HV) peach fruit internal quality. Given the lower vigor of ‘Sierra Rich,’ it was recorded that light was more evenly distributed throughout the canopy thus, hypothesized that this could be leading to fruit of uniform quality across the different positions. Fruit from the different canopy positions were assessed at the commercial harvest stage for size, dry matter content (DMC) and physiological maturity (index of absorbance difference, I_AD), using non-destructive visible (Vis) to near-infrared spectroscopy (NIRS). Fruit maturity and DMC advanced/increased with the elevated height of canopy in both cultivars. However, when controlling for equal maturity, only fruit coming from the vigorous ‘Cresthaven’ trees showed a significant (P ≤ 0.05) ΔDMC of 2.1 % between extreme canopy positions. Non-targeted metabolite profiling was carried out using gas chromatography mass spectrometry (GC–MS) on the mesocarp and exocarp of equally mature peach fruit samples. Mesocarp metabolite profiling of equally mature fruit coming from the different canopy positions demonstrated minimal metabolic variation. However, significant metabolite variation across canopy positions was observed in the exocarp of the HV cultivar. In general, sucrose, sorbitol and catechin were more abundant in higher quality, exposed to high-light environment fruit, while increased aspartic acid, asparagine, threonine, citric acid, monosaccharides (sorbose and fructose), butanoic acid and shikimic acid were associated with inferior quality, exposed to low-light environment fruit. Overall, this combined physiological and metabolomic analysis provides insight into the true impact of canopy position and underscores the light environment-related metabolic regulations that facilitate peach fruit quality development.

在不同树冠位置发育的果实暴露在不同的光照环境中，这会影响它们的成熟过程和内部质量的发育。成熟是一个在分子水平上受到高度调控的过程，它显着影响水果的品质。由于在之前的研究中对成熟度的控制不佳，我们对各种收获前因素对水果质量的真实影响的理解是有限的。在这里，进行了一项实验以评估冠层活力和位置（底部：0.3-1.2 m 和顶部：2.1-3.0 m）对“Sierra Rich”（低活力，LV）和“Cresthaven”（高活力， HV) 桃果实内在品质。鉴于 'Sierra Rich' 的活力较低，据记录，光线更均匀地分布在整个树冠中，因此，假设这可能导致不同位置的果实质量一致。在商业收获阶段评估来自不同冠层位置的果实的大小、干物质含量 (DMC) 和生理成熟度（吸光度差异指数，I_AD )，使用非破坏性可见光 (Vis) 到近红外光谱 (NIRS)。两个品种的果实成熟度和 DMC 都随着冠层高度的升高而提前/增加。然而，当控制等成熟度时，只有来自旺盛的 'Cresthaven' 树的果实表现出显着（P≤ 0.05) 极端树冠位置之间的 ΔDMC 为 2.1 %。使用气相色谱质谱法 (GC-MS) 对同样成熟的桃果实样品的中果皮和外果皮进行非靶向代谢物分析。来自不同冠层位置的同样成熟果实的中果皮代谢物分析表明代谢变异最小。然而，在 HV 栽培品种的外果皮中观察到跨冠层位置的显着代谢物变异。一般而言，暴露于高光环境的果实中，蔗糖、山梨糖醇和儿茶素含量更高，而天冬氨酸、天冬酰胺、苏氨酸、柠檬酸、单糖（山梨糖和果糖）、丁酸和莽草酸的增加与劣质、暴露于弱光环境的水果。总体，