Comparative analysis of salt tolerance in five commercial Prunus rootstocks

Salinity threatens agricultural productivity worldwide, particularly affecting fruit trees like Prunus species. Rootstocks can enhance salt tolerance, but comparative evaluations of modern commercial rootstocks under saline conditions remain limited. This study assessed salt tolerance mechanisms in five Prunus rootstocks (Garnem, GF677, Rootpac 20, Rootpac 40 and Rootpac R) under increasing NaCl concentrations.

Significant genotypic variation in salt tolerance was observed, with distinct parameter-specific responses challenging simple tolerance rankings. Rootpac R demonstrated balanced performance across growth, physiological and ion homeostasis parameters. Rootpac 20 maintained the best shoot elongation (only 9.9% reduction at 75 mmol L^-1 NaCl) despite severe ion dysregulation and near-complete defoliation, revealing independent tolerance mechanisms. GF677 performed well at moderate salinity but showed threshold effects at higher concentrations. Rootpac 40 maintained superior K⁺/Na⁺ ratios that did not translate to growth performance, while Garnem showed poor performance in both growth metrics despite large initial size. Initial vigor rankings (based on control performance) showed no correlation with salt tolerance, indicating that these traits are genetically independent.

Salt tolerance in Prunus rootstocks involves multiple, independent mechanisms including growth maintenance, ion selectivity and physiological stability. No single genotype exhibited universal superiority; instead, each employed distinct tolerance strategies with specific advantages. Rootpac R offers the most balanced performance for general saline conditions, while other genotypes may be preferred for specific situations: Rootpac 20 for short-term growth maintenance, Rootpac 40 for ion homeostasis priority or Garnem for mild stress conditions. These findings emphasize that rootstock selection must consider specific environmental conditions and production goals rather than relying on simple tolerance rankings. © 2025 Society of Chemical Industry.