Evaluating the predictability of SIF at multiple temporal scales for winter wheat yield in Huang-Huai-Hai plain

• SIF740 showed higher drought sensitivity than SIF683 and VIs during regreening. • Cumulative SIF during jointing-flowering best predicted yield without drought. • Under drought, yield correlation with SIF rose with time, peaking at season scale. As a remote sensing indicator of vegetation physiology, solar-induced chlorophyll fluorescence (SIF) serves as a proxy for photosynthesis and has been widely used for monitoring stress conditions such as drought and for estimating crop yields. However, few studies systematically evaluated the capacity of SIF to indicate crop yield variations under drought and non-drought conditions across different temporal scales. This study focused on the Huang-Huai-Hai Plain (HHHP) and used the Standardized Soil Moisture Index (SSMI) to identify the spatial distribution of agricultural drought. We compared the sensitivity of SIF740, SIF683, NDVI, and NIRv to drought during different growth stages of winter wheat, and examined the associations between SIF740 and winter wheat yield under drought and non-drought conditions at various temporal scales. The results indicated that SIF740 was more sensitive to drought than SIF683, NDVI, and NIRv, particularly during the regreening stage. Under non-drought conditions, cumulative SIF740 during the jointing-anthesis stage exhibited the strongest correlation with winter wheat yield, outperforming instantaneous and growing-season scale estimates. Under drought conditions, the association between SIF740 and yield improved with increasing temporal scale, with seasonal cumulative SIF740 showing the best performance. This study further elucidated the underlying mechanisms of the association between SIF and crop yield, providing a representative example for SIF-based regional yield estimation.