Training systems regulate the fruit quality of Korla fragrant pear through modifications of canopy structure and light interception

• Training systems regulate fruit quality via distinct canopy-structure and internal-light pathways. • A novel 3D framework quantifies canopy-light-fruit relationships for precision management. • Thinning best improves light in lower/inner zones, Falling heading favors upper/outer zones. • A clear trade-off exists: compact canopies favor quality uniformity, expansive ones boost yield. • Thinning enhances light and yield in dense orchards but requires fruit thinning to maintain quality. This study aimed to elucidate the mechanisms by which training systems influence fruit quality in Korla fragrant pear. This was achieved by precisely quantifying their effects on two key aspects: canopy structure and the internal light environment (PAR). The goal was to establish a functional framework to guide precision canopy management. Four distinct training systems were designed and implemented in a densely planted orchard. A novel three-dimensional spatial analysis framework was employed to synchronously measure detailed canopy structure parameters, PAR (photosynthetically active radiation) at different positions, and the corresponding fruit quality traits. Restrictive pruning maintained compact canopies (3 m³), while thinning practices promoted a dramatic, five-fold increase in canopy volume. Canopy height was the dominant structural factor governing the spatial distribution pattern of light within the canopy. Falling head improved LAI (light average intercaption) in the middle and upper layers, whereas Thinning enhanced it in the middle and lower layers. Training systems regulate pear fruit quality through two distinct pathways: canopy structure predominantly controls skin lightness and hardness, whereas within-canopy light distribution primarily governs skin redness and sugar content. Compact canopies favoring uniform quality and expansive canopies boosting yield. For high density orchards, canopy thinning improves light and yield.