Canopy Architecture and Light Use Efficiency in High-Yielding Maize Varieties Under Different Plant Populations in South West Nigeria

This study analyses canopy architecture characteristics and light use efficiency in high-yielding maize varieties under different plant population densities in South West Nigeria, contributing to the quantitative understanding of canopy physiology that underlies population density-yield relationships. Maximising maize yield under high-population density management requires varieties with canopy architectures that efficiently intercept and convert solar radiation across dense plant communities. The canopy physiology basis of yield-population responses in modern tropical maize hybrids has received limited study under South West Nigerian conditions. This study establishes a replicated canopy physiology experiment at Obafemi Awolowo University Ile-Ife and IITA Ibadan research farms, evaluating three advanced IITA maize hybrids and one open-pollinated variety at five population densities from 40,000 to 110,000 plants per hectare. Canopy light interception at multiple heights, leaf area index, extinction coefficient, photosynthetically active radiation at ear height, radiation use efficiency, and grain yield are measured at weekly intervals from emergence to maturity over two seasons. Findings reveal that radiation use efficiency is the strongest determinant of yield variation across population densities, accounting for 58 percent of yield variation in regression analysis. Advanced hybrids with erect leaf angles maintain higher PAR transmission to ear level at high populations compared to open-pollinated varieties with more horizontal leaf angles. Maximum RUE for the best hybrid reaches 3.8 grams per megajoule, comparable to values reported for temperate hybrids. The study contributes original canopy physiology data for tropical maize and recommends selection for erect leaf angle as a criterion for high-population density adaptation in Nigerian maize breeding.

Keywords: canopy architecture, light use efficiency, maize, plant population, South West Nigeria.