Efficient Production of Vigorous Scions by Optimizing Leaf Retention in Passiflora edulis

Passiflora edulis propagation relies extensively on grafting, yet the optimization of pruning strategies for scion quality remains empirically guided. This study elucidates the physiological and molecular mechanisms underlying scion quality across five leaf retention treatments (0%, 25%, 50%, 75%, and unpruned control). The 50% partial leaf retention (50% PLR) treatment optimally promoted axillary bud development in passion fruit through coordinated physiological and molecular adaptations. This treatment significantly outperformed other treatments in terms of both bud sprouting rate and growth parameters (including length and diameter). Physiological analyses demonstrated transient auxin accumulation coupled with synchronized antioxidant system activation, maintaining redox homeostasis. Transcriptomic profiling identified upregulation of genes in the auxin signaling pathway and cytokinin activators, while dormancy-related genes were suppressed. These findings establish 50% PLR as an optimal threshold that balances photosynthetic capacity with hormonal regulation, providing a science-based strategy to standardize grafted seedling production, while enhancing scion quality for grafting efficiency.