Comprehensive analysis of the effects of foliar application of the synthetic strigolactone analog GR24 during the growth period on postharvest quality and metabolic indicators of pak choi.

Strigolactones (SLs) regulate plant growth and metabolism, but their concentration-dependent effects on leafy vegetable quality remain unclear. We investigated how the synthetic SL analog GR24 affects physiological and metabolic processes in pak choi (Brassica rapa subsp. chinensis). Mantel correlation analysis and partial least squares structural equation modeling (PLS-SEM) revealed distinct response patterns. The 1 μmol·L-1 treatment (T2) enhanced photosynthesis, carbon‑nitrogen assimilation, mineral accumulation, and GA3, ZT, ABA, and JA levels, whereas the 10 μmol·L-1 treatment (T3) promoted carotenoid and phenolic accumulation, including rutin, ferulic acid, and caffeic acid. Multivariate analysis linked phenolic acid accumulation mainly to nitrogen and amino acid metabolism, with additional associations with P status. Overall, T2 broadly enhanced primary metabolism and nutrition, whereas T3 favored secondary and antioxidant-related metabolism, providing a framework for optimizing GR24 application in high-quality leafy vegetable production.