Climate warming causes changes in wheat phenological development that benefit yield in the Sichuan Basin of China

The effects of climate warming on wheat yields vary geographically under different warming scenarios. Such variations reflect real climatic differences and our insufficient understanding of how physiological processes respond to warming conditions. In this study, a 16-year trial comprising three crop production systems (CPSs) and a 5-year trial including seven cultivars were conducted in the Sichuan Basin of China to investigate the effects of climate warming on the phenological development, grain yield (GY), dry matter (DM) accumulation and translocation of wheat. The three CPSs included conventional rotary tillage with residue removal for both rice and wheat (CPS1), conventional rotary tillage with the wheat residue incorporated for the rice following zero tillage with residue-mulching for wheat (CPS2), and zero tillage and residue-mulching employed for both wheat and rice (CPS3). The wheat cultivars used in this study were all spring-type wheat, and the trials were planted from 26 to 30 October each year, irrigation was applied only at the seeding and topdressing stages and in amounts less than 20 mm. The results showed that mean of daily mean temperature from November to March (MTNₒᵥ₋Mₐᵣ) and November to April (MTNₒᵥ₋Aₚᵣ) significantly increased by 0.0964 °C yr⁻¹ and 0.0947 °C yr⁻¹ from 2004 to 2020, respectively. This warming caused earlier flowering and significantly decreased mean temperature from anthesis to maturity (PₒₛₜATₘₑₐₙ) by 0.091 °C yr⁻¹. However, grain number m⁻² was unaffected by this warming. Cooler and longer grain-gilling periods (GFP) lead to larger grain sinks and allow more preanthesis assimilates to be transported to the grain, resulting in increased individual grain weight and harvest index under all CPSs and all cultivars. There were no significant differences in sensitivities of GY and DM related trait responses to temperature change between CPSs or between cultivars. Averaged over all CPSs, GY increased 741.9 kg ha⁻¹ with each 1 °C increases in MTNₒᵥ₋Aₚᵣ. The increase in yield was mainly attributable to increase in grain weights while grain number m⁻² was maintained. In addition, the MTNₒᵥ₋Aₚᵣ values in the Sichuan Basin were predicted to reach 14.7 °C and 16.5 °C by the end of this century under the SSP245 and SSP585 climate change scenarios, respectively. When the CO₂ concentration was fixed at 350 ppm, the Agricultural Production Systems SIMulator (APSIM) model showed that the increasing MTNₒᵥ₋Aₚᵣ values significantly increased the GY under the SSP245 scenario, but the GY was initially positively and then negatively affected under the SSP585 scenario. These results lay the foundation for developing adaptation strategies to address future climate change in climates like that of Sichuan Basin and ensure wheat supplies.