Climate variability increasingly constrains genetic gains in rapeseed oil content: A survey on big data

Recent advances in crop breeding have improved the potential for quality enhancement, yet how climate variability constrains the realization of these gains remains insufficiently understood. Here, we compiled 16,424 production-scale observations of winter rapeseed oil content from the Yangtze River Basin during 2008 to 2022 and used a stage-resolved analytical framework to quantify climate-associated constraints on realized oil-content gains. Rapeseed oil content showed a significant long-term upward trend, with an ordinary least squares slope of 0.24% per year. However, climate effects increasingly reduced the realized gains over time: the mean signed climate contribution declined from -0.01% (2008- 2012) to -1.06% (2013 - 2017) and further to -1.75% (2018- 2022). Extreme heat exposure was negatively associated with oil content, and the strongest effect was observed in the Middle Yangtze River Basin, where the coefficient for extreme degree days reached -0.06. Stage-specific and SHapley Additive exPlanations (SHAP)-based analyses showed that the declines in oil-content were mainly associated with heat- and moisture-related signals during key developmental periods. Flowering exhibited the greatest climate sensitivity, with the largest median permutation-induced R 2 decline of 0.47. These findings highlighted the increasing climate constraints on rapeseed oil-content gains and the need for greater climate resilience in breeding.