Adapting maize cultivation to late sowing: integrated strategies of planting density and hybrid maturity to ensure production

1 Post-silking GDD over 728°C d enabled yield gains from raising planting density. 2 Raising density to 82500 plants ha −1 mitigated yield losses in late-June sowing. 3 Early-maturing hybrids at low density reduced yield losses in early-July sowing. Climate warming and the increasing unpredictability of precipitation have led to frequent sowing delays for summer maize, severely affecting maize production. This study aimed to identify strategies to minimize yield losses and enhance mechanical harvest quality under various late-sowing scenarios by optimizing planting density and hybrid maturity, along with understanding the underlying mechanisms. A field experiment was conducted from 2022 to 2024 in the Huanghuaihai Plain (HHHP), China, involving three sowing dates (mid-June, late-June and early-July), three planting densities (67,500, 82,500 and 9,7500 plants ha −1 ), and two hybrid types (early-maturing and late-maturing). The results showed that maize production's response to planting density was governed by post-silking growing degree days (GDD). When post-silking GDD exceeded 728°C d, increasing planting density to 82,500 plants ha −1 significantly enhanced leaf area index (17.0%), canopy radiation interception (4.2%) and maximum grain filling rate (15.5%), thereby increasing post-silking dry matter accumulation by 8.6% and mitigating yield losses from delayed sowing by 7.1%. Planting early-maturing hybrids was more conducive to reducing harvest grain moisture by 7.2% while maintaining yield. These optimized practices are applicable to over 94.6% of regions in HHHP under late-June sowing scenarios in the 2030s. Conversely, when post-silking GDD was below 685°C d, insufficient GDD significantly inhibited maize growth at both individual and population levels, resulting in 41.5% yield losses and a 53.8% increase in grain moisture. About 87% of regions cannot compensate for yield losses by increasing planting density. Under these conditions, planting early-maturing hybrids at lower densities proved more advantageous for minimizing yield loss and grain moisture at harvest, especially north of 33.7°N. These findings provide a theoretical basis for strategies to reduce yield loss from late sowing under climate warming and unpredictable rainfall.