The study demonstrates that the GIGANTEA (GI) protein is a core component of the wheat circadian clock, required for robust oscillations in chlorophyll fluorescence and clock gene expression. Loss of functional GI leads to delayed heading under both long and short photoperiods, indicating a photoperiod‑1‑dependent pathway distinct from Arabidopsis. These findings provide insight into photoperiodic regulation of flowering in wheat, informing breeding strategies for high‑yield cultivars.