Field experiments were conducted at ChukwuemekaOdumegwuOjukwu University, Igbariam research field in 2019 and 2020 cropping seasons. The objectives were to evaluate the biomass and grain yield of six sorghum cultivars (CSR01, Samsorg11, Samsorg40, Samsorg44, Samsorg45 and Samsorg46) under four plant densities (941760, 1333000, 2182000 and 5714000 plants/ha) constituted the treatments which were laid out in a randomized complete block design (RCBD) with three replications. Data collected were subjected to analysis of variance (ANOVA) and significant mean were separated using Fisher’s Least Significant Difference (LSD). The tested parameters were fresh, dry matter (biomass) and grain yield of all the investigated cultivars. Cultivars CSR01 and Samsorg11 (748.20 and 697.14 respectively) were the most productive in respect to biomass yield while cultivar Samsorg40 was least productive. For grain yield, cultivars samsorg11 and CSR01 were significantly the best. Biomass and grain yield increased with increase in Plant density. Plant density 1333000 plant/ha and 2182000 plant/ha were the best since they produced the largest biomass and grain yield. A sharp reduction was observed from the result as density increased to 5714000 plants/ha. Therefore, these integrated treatments were recommended for maximum biomass and yield. Extreme plant density reduced dry matter and grain yield due to plant competition for resources.

Keywords: Population density, yield, sorghum, biomass, growth.