Sub-optimal plant density is a significant factor limiting the profitability of maize (Zea mays L.) production in Nigeria. Despite this, the maize planting density recommendation has remained constant at 53,333 plants per hectare across various maize genotypes and agroecologies. Increasing plant density has the potential to enhance resource utilization and improve maize productivity.

In this study, two open-pollinated maize varieties (DMRLSR-W and SUWAN-1) and two hybrids (OBASUPER-1 and OBASUPER-2) were grown under two plant densities: 80,000 and 53,333 plants per hectare. The experiment was conducted at the Institute of Agricultural Research and Training, Ibadan, during the 2017 and 2018 growing seasons. The treatments were arranged in split-plots using a Randomized Complete Block Design (RCBD) with three replications. Data were collected on maize growth parameters, yield components, and grain yield (GY), and the data were subjected to analysis of variance (ANOVA) at a 95% confidence level.

Results showed that the 80,000 plants per hectare density significantly (P < 0.05) increased grain yield (GY), with 3.29 t/ha compared to 2.83 t/ha at 53,333 plants/ha. There were no significant differences in grain yield between the maize varieties at P < 0.05. Among the varieties, OBASUPER-1 (189.21 cm) and SUWAN-1 (191.85 cm) exhibited higher plant heights compared to OBASUPER-2 (175.04 cm) and DMRLSR-W (176.57 cm). Additionally, OBASUPER-1 (30.38 g) had the highest 100-seed weight, followed by OBASUPER-2 (27.58 g), DMRLSR-W (27.08 g), and SUWAN-1 (27.42 g).

The study concludes that increasing plant density to 80,000 plants per hectare significantly enhanced maize yield compared to the standard 53,333 plants per hectare. The findings suggest that further exploration of these and other maize varieties under higher plant densities across different agroecologies would be beneficial for optimal resource utilization and increased output