Optimizing sowing dates increase solar radiation to mitigate maize lodging and yield variability: A five-year field study

Optimizing sowing dates (SDs) is a potential strategy for adjusting maize production to climate change and increasing yield. However, there is still a lack of research on the combined effects of lodging and yield in relation to climatic variables across various SDs. This study aims to investigate the changing patterns and distribution of important climatic variables during the maize growth season, their impact on yield and lodging, and the critical factors affecting lodging at crucial growth stages under different SD scenarios. In this study, we assessed the impact of climate change on yield and lodging by conducting field experiments over 5 years (2015, 2016, 2019–2021) encompassing 25 SDs in the Sichuan basin, China. Results demonstrated that the lodging rate had a significant effect on the coefficient of variation (CV, 3.31–10.50%) of maize yield. A 1% increase in lodging rate, led to a decrease of 58.05 kg ha-1 in yield. Changes in SDs notably affected solar radiation (Sr) from emergence to silking (E-R1). Additionally, the study found that Sr explained 34.7% of the lodging rate variation in E-R1. Analysis of historical meteorological data showed notable inter-annual variations in Sr trends, with a decline of -8.7763 MJ m-2 yr-1 from 1990 to 2021, especially noticeable from late May to early July. Variation Partitioning Analysis (VPA) revealed that climatic variables during the period from emergence to physiological maturity (E-R6) and E-R1 explained 43.9 and 53.2% of yield, respectively, across different SDs. These variables also contributed 56.0 and 45.4% to lodging. Using Random Forest (RF) determined that changes in SDs significantly impacted lodging rates mainly through modifications in basal internode morphology, which explained 69.79% of the variation. The study identified optimal sowing dates for achieving high and consistent yields, primarily occurring between late March and mid-April, attributed to increased Sr during E-R1. Overall, this research provides valuable insights into the effects of climate change on stalk lodging and offers guidance on adjusting sowing dates to mitigate maize lodging rates.