Yield response of maize hybrids with different ear flex to nitrogen rate and plant density

Abstract

AbstractMaize (Zea mays L.) hybrids are frequently labeled as fixed or flex hybrid ear types by seed companies based on pre‐commercial trials or field observations during commercialization. However, the underlying physiological cause and the associated management with each hybrid ear type remains a question for growers. Experiments were conducted at multiple locations across 3 years to determine the yield and yield component response to combinations of plant density (4, 6, 8, 10, and 12 plant m−2) and nitrogen (N) rate (0, 78, 159, 235, and 314 kg N ha−1) for three fixed and four flex hybrid ear types. Optimal plant density (OPD) to reach maximum yield was 1.7 plant m−2 greater for fixed hybrid ear type compared to the flex hybrid ear type for N rates greater than 78 kg N ha−1. Flex hybrid ear type achieved similar yield at lower OPD through increased kernel weight (KW) without reduced kernels per square meter. Potential kernel number at silk appearance and established kernels 15 days after silk appearance were similar between hybrid ear types, indicating that the flex component was driven by KW. Fixed hybrid ear type displayed a lower threshold value of total aboveground biomass per plant at physiological maturity to set kernels compared to a flex hybrid ear type. Selection of a flex hybrid ear type provides opportunity for reduced planting density with similar yield potential and N management practices.