LIGHT DISTRIBUTION WITHIN APPLE TREE CANOPIES UNDER DIFFERENT SLOPE ASPECTS AND ROW ORIENTATIONS

Abstract

The study (2022–2025, Central fruit-growing zone of the Republic of Moldova) evaluated the light microclimate in two contrasting apple orchard configurations: super-intensive on flat terrain ('Gala'/M9, North–South row orientation) and intensive on a 5° northern slope ('Golden Delicious'/M26, East–West row orientation). Actinometric results show that the North–South
orientation on flat terrain ensures homogeneous and symmetrical illumination between the eastern and western canopy flanks (a difference of only ~3 %). In contrast, the East–West orientation on the northern slope generates a pronounced radiative asymmetry, with the northern flank experiencing a 38 % light deficit compared to the southern flank (0.45 vs. 0.73 cal/cm²·min). Furthermore, the wider canopy (B = 2.0 m) on the slope reduces basal radiation to 0.31 cal/cm²·min. For northern slopes, an H/L ratio of 0.87 causes mutual shading. Reducing tree height to 2.8–3.0 m (H/L = 0.70–0.75), limiting canopy width below 1.5 m, and
performing thinning pruning in the upper canopy tier are recommended to optimize insolation.