Agronomic and Physiological Aspects of Programmed Cycle Pruning in Coffea arabica

Programmed Cycle Pruning (PCP) in Arabica coffee can positively influence plant physiology by modifying plant architecture, promoting a more uniform distribution of branches and leaves, and altering microclimatic conditions within the canopy, particularly light incidence. These structural changes may contribute to improvements in plant performance and productivity. The objective of this study was to evaluate growth, yield, and physiological responses of Arabica coffee plants managed under PCP at different stem densities per hectare. The experiment was conducted in a randomized block design with four replications. Treatments were arranged in a 4 × 2 factorial scheme with an additional treatment representing the traditional pruning system. The factorial combination included four stem densities (4000, 8000, 12,000, and 16,000 stems ha^-1) and two data collection positions on the plant (lower and upper canopy strata). The evaluated variables included canopy diameter, plagiotropic branch length, number of inflorescences per branch, net photosynthetic rate (Anet), stomatal conductance (gs), leaf transpiration (E), vapor pressure deficit between leaf and air (VPDleaf/air), SPAD index, anthocyanin and flavonoid contents, and grain yield. PCP promoted greater uniformity in leaf gas exchange within the canopy and prevented the occurrence of "girdling", which under traditional pruning reduced Anet in the upper canopy. Net photosynthesis increased with stem density under PCP. Although growth variables were similar between pruning systems, yield was higher under PCP, with a nonlinear response to stem density, indicating improved canopy gas-exchange uniformity and productivity in Arabica coffee cultivation.