Morpho-Physiological Characteristics and Dry Matter Partitioning As Influenced By Plant Density in Commercial Maize Genotypes in Nigeria.

Maize genotypes respond differently to plant population densities in their morpho-physiological, dry matter partitioning and yield. For effective utilization of growth resources and maximum grain yield to be obtained, optimum plant density is imperative. Studies were therefore carried out in both late and early rainy seasons to evaluate the morpho-physiological characteristics, dry matter accumulation and distribution as well as grain yield of maize genotypes using different plant densities. The treatments were three commercial maize genotypes: single cross hybrid (Oba Super 1) and two open pollinated genotypes (Suwan -2 and Suwan -1) and four plant density levels: 37,000plants/ha (90x30cm), 53,333plants/ha (75x25cm), 66,667plants/ha (60x25cm) and 80,000plants/ha (50x25cm). In the growth rate measurements, planting density affected the leaf area index (LAI), crop growth rate (CGR) and net assimilation rate with high density producing high values while there was no significant density effect on the leaf area ratio (LAR). Highest values for total dry matter per unit area were obtained at 80,000plants/ha. The percentage total dry matter increase of 80,000 plants/ha over the 66.667, 53,333 and 37,000 plants/ ha ranged from 1.0% - 60.8% in the three genotypes. Grain yield increased significantly with increase in plant density with the highest value at 80,000 plants/ha (6.16t/ha); significantly higher than grain yield obtained at 37,000plants/ha (3.88t//ha) in the early season. In the late season, highest grain yield was obtained at 80,000plants/ha (6.07t/ha); significantly higher than values obtained at 53,333 plants/ha and 37,000plants/ha. Among morpho-physiological traits, plant height, number of leaves, stem girth, leaf area duration (LAD) and LAI had significant and positive correlation with grain yield, no correlation among LAR, CGR and grain yield while plant aspect showed negative significant correlation. Grain yield of maize in the derived savannah ecology of southwest Nigeria can be increased by increasing plant density level up to 80,000plants/ha.