Boron enhances morphophysiological development of arabica coffee minicuttings under variable exogenous sucrose and leaf area

Vegetative propagation via stem cuttings is a critical strategy for clonal multiplication of elite Coffea arabica genotypes. However, rooting success and shoot development depend on a complex interplay of nutritional, hormonal, and physiological factors. This study evaluated the effects of boron (B) supplementation in the rooting solution with foliar sucrose application (0, 10, and 20 g L⁻¹), and retained leaf area (25%, 50%, and 75%) on the morphophysiological development of C. arabica cuttings. The experiment followed a triple factorial (2 x 3 x 3) design, using indole-3-butyric acid (IBA) in all treatments. Morphological parameters related to shoot growth and root architecture were measured, and data were analyzed using linear mixed-effects models and multivariate principal component analysis (PCA). The results demonstrated that B supplementation significantly enhanced shoot elongation, stem diameter, and new leaf emergence, particularly under higher retained leaf area and foliar sucrose levels. Root volume, length, surface area, and dry mass also improved markedly with B application, irrespective of sucrose supply. PCA revealed strong segregation between B-treated and untreated groups, highlighting the structural and physiological integration promoted by boron. These findings suggest that optimizing B supply, leaf retention, and exogenous carbon application may substantially improve propagation efficiency in C. arabica nurseries.