Grafting on resistant rootstocks alleviates salt stress on tomato by enhancing morpho-physiological and biochemical...

Salinity is a global threat to crop production, reducing yields and jeopardizing food and nutrition security. This study was performed to evaluate the salinity tolerance of high-yielding commercial tomato 'Super Sweet F₁'(SS), which was self-grafted, or cross-grafted with salt-tolerant rootstocks 'Maxifort F₁' (MF), 'Pimp-M021'(PM), and 'Ramsi' (RM). The plants were evaluated at low (18.2 mM NaCl) and high-water salinity (150 mM NaCl). The cross-grafted plants SS/MF and SS/PM showed similar responses under high salinity with increased leaf chlorophyll concentration, relative water content (RWC), membrane stability index (MSI), Na⁺ and K⁺ concentration, electrolyte leakage (EL), stomatal conductance, fruit number, and weight, when compared to non-grafted and self-grafted plants. Due to the salt stress, elevated activities of proline, total phenols (TPC), total flavonoids (TFC), polyphenol oxidase (PPO; EC 1.14.18.1), peroxidase (POD; EC 1.11.1.7), catalase (CAT; EC 1.11.1.6), and superoxide dismutase (SOD; EC 1.15.1.1) were also measured in the leaves of SS/MF, SS/PM, and SS/RM in comparison with SS and SS/SS. The principal component biplot analysis confirmed that the grafted tomatoes, SS/MF and SS/PM, showed improved performance under salt stress compared with non-grafted, self-grafted, and cross-grafted SS/RM plants. This study revealed that Pimp-M021'(PM) could be a promising candidate beside the commercial Maxifort F₁ (MF) rootstock for tomato under salt stress conditions. Our findings demonstrated the positive effects of salt-tolerant rootstocks on tomato growth, yield, and fruit characteristics, and this could herald a sustainable tomato production practice in salinity-prone areas worldwide.