Population optimization and solar-thermal allocation were key drives for yield resilience in delayed sown wheat...

More frequently extreme precipitation delayed sowing window of winter wheat (Triticum aestivum L.) in North China Plain (NCP), which could change wheat phenological development, threatening yield formation. Widely, increased seeding rates were a proposed strategy to maximize potential yields. There is a clear need to examine the effects of delayed sowing and increased seeding rates on key wheat parameters, including phenology, growth and development. A 2-year field experiment was conducted with three sowing dates (conventional date, Con; delayed 7 days, D7; delayed 14 days, D14) and two seeding rates (250 seeds m^-2, Nor; 310 seeds m^-2, Inc).

Results showed that without abundant pre-winter photothermal resources, yields under delayed sowing decreased by 7.60% (D7) and 18.04% (D14) compared with Con. However, Inc could alleviate and even reverse the yield loss caused by delayed sowing, which primarily was due to 29.95% higher pre-winter population and 9.40% more final spikes than Nor. Additionally, post-winter thermal accumulation under delayed sowing increased by 24.57-72.62 d °C compared to Con, which ensured higher tillers improvement from overwintering to jointing, increased relative growth rate by 38.52-109.69% compared to Con after jointing and prolonged effective grain-filling duration. Notably, compared with Nor-Con, the Inc-D7 effectively balanced crop population and individual characteristics, thereby achieved a 101.82% reversal in aboveground biomass accumulation and a 7.03% yield increase.

Inc-D7 combination established yield resilience by establishing optimal population and adaptive growth regulation, which provided valuable information to secure production stability in the NCP agricultural system to cope with climate changes. © 2026 Society of Chemical Industry.