Pathways to increase maize yield in Northwest China: A multi-year, multi-variety analysis

Identifying methods to increase maize production is of great significance to ensuring food security. We here collected and analyzed data from 160 plots containing 134 maize varieties grown from 2010 to 2020. Plots were divided into three yield bands: < 15, 15–18, and > 18 t ha−1. The effects of dry matter (DM) accumulation, leaf area index (LAI), and growth period on yield were analyzed, and the contributions of individual yield components to the final yield were determined. The average yield was 16.62 t ha−1, with a range of 10.44–22.52 t ha−1. Increases in yield from < 15 to > 18 t ha−1 were associated with increases of 12.8%, 24.0%, 6.1%, 20.4%, 24.6%, and 13.8% in harvest ear number, kernel weight per ear (KWE), kernel number per ear (KNE), 1000 kernel weight (1000-KW), pre-silking DM, and total DM, respectively. LAI at the silking stage (R1) and at maturity (R6) also increased by 9.0% and 3.6%, respectively. Yield first increased, then decreased along with increases in harvest ear number, and the highest yield was obtained when the harvest ear number was 12.13 × 104 ears ha−1. Yield was significantly and positively correlated with KWE, KNE, and 1000-KW. Higher KNE and 1000-KW were associated with higher yield due to increased KWE. Pre-silking DM (Pre-DM) had a greater effect on yield than Post-silking DM (Post-DM) did. The increase in R1 LAI enhanced the photosynthetic capacity of the maize population and promoted Pre-DM accumulation and Total-DM accumulation in the maize population, thus enabling higher total yield. The contributions of KWE, Pre-DM, and R1 LAI to yield increased from the lowest to the highest yield band, whereas the contributions of harvest ear number, Post-DM, and R6 LAI decreased. In conclusion, current yield levels indicate that yield could be optimized by enhancing population LAI, the DM distribution ratio, and yield composition through three main strategies: selection of varieties tolerant to high-density planting; increasing planting density; and implementing rational water and fertilizer application strategies.