QTL identification of ear leaf morphometric traits under different nitrogen regimes in maize

The ear leaf is one of the most important leaves in maize (Zea mays); it affects plant morphology and yield. To better understand its genetic basis, we examined ear leaf length, ear leaf width, and ear leaf area for quantitative trait locus (QTL) mapping in a recombinant inbred line population under two nitrogen regimes. Nine QTLs, on chromosomes 1 (one), 2 (one), 3 (one), 4 (three), 7 (one), and 8 (two), were mapped under the high nitrogen regime, which explained phenotypic variation ranging from 5.4 to 14.8%. Under the low nitrogen regime, 7 QTLs were located on chromosomes 1 (one), 4 (two), 7 (one), and 8 (three), which accounted for phenotypic variation ranging from 5.5 to 20.5%. These QTLs had different mapping intervals to their nearest markers, ranging from 0.3 to 21.0 cM. Due to additive effects, 3 and 13 QTLs can cause phenotypic values of these traits to increase or decrease to some extent, respectively. This information will help understand the genetic basis of ear leaf formation and will be useful for developing marker-assisted selection in maize-breeding projects.