Mixing trait-based corn (Zea mays L.) cultivars increases yield through pollination synchronization and increased cross-fertilization

Abiotic stress such as high temperature at flowering is one of many conditions reducing yield of corn (Zea mays L.). Mixing corn cultivars with diverse functional traits increases within-crop diversity and provides a potential means of mitigating yield losses under stress conditions. We conducted a three-year field study to investigate the effects of cultivar mixtures on kernel setting rate, pollen sources, and yield. This study consisted of six treatments, including two high temperature-tolerant (HTT) monocrops of WK702 and DH701, two high temperature-sensitive (HTS) monocrops of DH605 and DH662, and two HTT–HTS mixtures of WK702-DH605 and DH701-DH662. The anthesis–silking interval (ASI) was 0.9–1.6 days shorter in mixtures than in monocrops. Kernel setting rate was increased in mixtures (86.4%–88.7%) compared with those in monocrops (74.7%–84.1%) as a result of synchrony and complementarity of pollination. Grain yields of the HTT–HTS mixtures increased by 13.3%–18.7%, equivalent to 1169 to 1605 kg ha−1, in comparison with HTS corn monocrops. The results of SSR markers showed that cross-fertilization percentage in corn cultivar mixtures ranged from 29.3% to 47.8%, partially explaining yield improvement. Land equivalent ratio (LER) was 1.12 for corn mixtures and the partial land equivalent ratio (e.g., > 0.5) showed the complementary benefits in corn mixtures. The results indicated that mixing corn cultivars with diverse flowering and drought-tolerance traits increased yields via pollination synchrony.