Comparison of Inbred and Hybrid Corn Grain Yield Measured at Equal Leaf Area Index

Grain yield of 44 single crosses and their component inbreds of corn (Zea mays L.) was determined over a wide range of plant populations. Yield was determined for inbreds and single cross hybrids at unit intervals of leaf area index (LAI) of 1–4. Mean inbred yield was no greater than 60% of the mean hybrid yield, regardless of whether yields were compared at a common plant density or LAI. Optimum LAI (LAI where grain yield was at its maximum) was higher for the hybrids than for the inbreds.