Alginate Hydrogel with Pluronic F-68 Enhances Cryopreservation Efficiency in Peach Germplasm

The long-term conservation of <i>Prunus persica</i> (peach), a crop of significant agronomic and genetic value, remains challenging due to its recalcitrance to conventional cryopreservation methods. Low tolerance to dehydration and cryoprotectant toxicity often results in poor survival and regrowth, thereby limiting the reliability of germplasm storage. This study evaluated whether combining an alginate hydrogel matrix with Pluronic F-68 improves vitrification efficiency and post-thaw regeneration of peach shoot tips by enhancing dehydration dynamics and reducing cryo-injury. Shoot tips were immobilized in thin sodium alginate layers on aluminum foil strips, with the hydrogel providing mechanical stabilization and moderating water loss during exposure to PVS3 and subsequent liquid nitrogen immersion. To further mitigate cryoinjury, Pluronic F-68, a non-ionic surfactant with membrane-stabilizing properties, was incorporated into the system. Differential scanning calorimetry revealed that the hydrogel reached complete vitrification after 120 min in PVS3, whereas encapsulated shoot tips required 150 min for full suppression of crystallization. The optimized system achieved 71% post-cryopreservation survival and 40% regrowth, compared with 25% and 9% in non-encapsulated controls. PF-68 accelerated vitrification kinetics, lowered crystallization enthalpies, and improved post-thaw viability. These findings demonstrate that engineered hydrogel-surfactant matrices can stabilize the microenvironment during vitrification and offer a promising approach for the long-term cryopreservation of peach germplasm.