Designing virtual maize cultivars with optimal planting date and density can improve yield and water use efficiency under plastic mulching conditions

Context: Global food production is facing severe challenges due to climate change. Previous climate-crop modeling studies have developed multiple adaptation strategies, such as adjusting sowing dates, densities, and optimizing cultivars, to counteract the negative impacts of climate change. In northwest China, plastic mulching (PM) is extensively utilized to alleviate drought stress, improving both yield and water use efficiency (WUE). Nonetheless, the integration of PM with prevalent agricultural practices to formulate a comprehensive strategy for adapting to climate change has not been investigated. Objective: We aim to integrate different virtual cultivars, sowing dates, and plant densities with PM practices to identify the most effective strategies for enhancing yield and WUE under climate change. Methods: The simulation of maize yield and WUE under adaptive conditions was conducted using the SPACSYS (Soil-Plant-Atmosphere Continuum System) model. The model was calibrated and validated with five-year field observation data at Yangling in northwest China. It was driven by climate data projected from one Global Climate Model identified as representing the worst-case scenario from the Coupled Model Intercomparison Project phase 6 for the study site. The simulations were based on a high emission scenario of future societal development pathway (SSP585) during two periods (2021–2060 and 2061–2100). Results: Our simulation results show that future maize yield without adaptation was projected to decrease by 4.3 % in the 2040s (2021–2060) and 56.0 % in the 2080s (2061–2100). We found that postponing sowing dates by 15 days and increasing plant density to 7.5–9 plants m^–2 can boost yield and WUE in future climate scenarios. Furthermore, when PM was integrated with optimal virtual cultivar under optimal planting date and density, the simulated yield rose by 97.6 % and 25.5 % in the 2040s and 2080s, respectively, relative to the reference management, while WUE rose by 162 % and 114 %, respectively. Conclusions: Integrating PM with delayed sowing and higher planting densities can enhance maize yield and WUE under future climates. An optimal climate-adapted maize cultivar should have longer growth durations, higher specific leaf area, and improved carbohydrate transfer rates than current cultivars. These results underscore the significant potential of combining optimal genotype and agronomic options to enhance yield and WUE under climate change in arid rainfed regions. Significance: This research offers valuable insights for breeders and agronomists in formulating genotype × management strategies to cope with climate change.