Variability for Morphological and Physiological Traits Associated with Barrenness and Grain Yield in the Maize Population, Iowa Upright Leaf Synthetic #11

Barrenness, the failure of a plant to produce a normal ear, is a major limitation to efficient conversion of light energy into grain in maize (Zea maysL.) grown at high plant densities. Our research was conducted to determine magnitudes of genetic variability and heritabilities for various traits of the maize population Iowa Upright Leaf Synthetic #1 (BSUL1) and to determine which traits were associated with barrenness and grain yield at high plant densities. We grew 144 S1lines from BSUL1 for 2 years at one location and at two plant densities. Results indicated that BSUL1 contained large amounts of genetic variability for the 14 traits studied at 42,300 and 96,800 plants/ha. Significant heritabilities ranged from 0.31 for grain/leaf area at the high density to 0.91 for tassel branch number (low density). Phenotypic and genotypic correlations indicated that silking traits, pullen‐shed‐to‐silking interval, and grain/plant were highly correlated with grain yield and barrenness at both densities. Canopy orientation traits generally showed weak associations with grain yield and barrenness. Correlations and genotype × year interactions suggested that selection at a low density (42,300 plants/ha) in one location for traits correlated with barrenness should improve BSUL1 for tolerance to high plant densities.