Climatic suitability and future dynamics of test-weight-defined high-quality wheat in China under climate change

Climate change is expected to affect crop production and grain quality by altering the environmental conditions that define crop climatic niches. However, the spatial distribution and future dynamics of climatic suitability for test-weight-defined high-quality wheat in China remain insufficiently understood. This study aimed to characterize the climatic suitability of high-test-weight (High-TW) wheat and assess its potential changes under future climate scenarios.

High-TW wheat was defined as wheat with a test weight (TW) ≥ 750 g L^-1. Long-term wheat quality monitoring records, WorldClim bioclimatic variables, BCC-CSM2-MR-based future climate projections, and an optimized MaxEnt model were used to characterize the baseline suitability pattern, identify dominant climatic predictors, and project changes under four future climate scenarios.

The model showed strong discrimination under random holdout evaluation, with a mean test AUC of 0.936 and a continuous Boyce index of 0.9702. The minimum temperature of the coldest month (Bio6) was the dominant predictor, contributing 55.3% to the model, indicating the importance of winter thermal conditions in the climatic niche associated with High-TW wheat. Under the 1970-2000 baseline climate, high-suitability areas were mainly concentrated in the north-central Huang-Huai-Hai Plain, broadly corresponding to traditional production regions of strong- and medium-strong-gluten wheat. Under the BCC-CSM2-MR projections, the broad spatial pattern remained relatively stable, while changes occurred mainly in the composition and peripheral distribution of suitability classes. By 2081-2100, high-suitability area increased under all four scenarios, with the largest relative increase under SSP126 (+12.35%). Centroid shifts were modest and scenario-dependent rather than proportional to emission intensity, with the largest late-century displacement reaching approximately 48 km under SSP370.

Future climate change may primarily reorganize the internal structure of climatic suitability while maintaining the broad national-scale pattern of High-TW wheat suitability. These findings provide a national-scale climatic-suitability perspective for High-TW wheat zoning, regional adaptation, and future production-planning assessments in China.