EFFECTS OF SEED DENSITY ON GROWTH AND BIOMASS PRODUCTION OF SOYBEANS

Soybean (Glycine max L.) is an essential legume crop that contributes significantly to global food security, human nutrition, and livestock feed due to its high protein and oil content. However, optimizing agronomic factors such as seed density remains critical for improving its productivity, particularly in semi-arid regions like Maiduguri, Nigeria, where research on this aspect is limited. This study investigated the effect of varying seed densities on the growth and biomass production of soybean under controlled conditions. A randomized complete block design (RCBD) was adopted, consisting of four treatments low (10 seeds/polythene bag), medium (20 seeds/polythene bag), high (30 seeds/polythene bag), and very high (40 seeds/polythene bag) seed densities with uniform irrigation and nutrient management. Growth parameters, including plant height, leaf area, biomass accumulation, and grain yield, were recorded weekly over an eight-week period. Results revealed that seed density significantly influenced soybean growth and development. The very high-density treatment (40s) produced the tallest plants (80.3 cm) and the largest leaf area (57.7 cm²) by the eighth week after planting (WAP), compared to 59.0 cm and 43.0 cm² respectively in the low-density treatment (10s). Biomass production and yield also increased proportionally with seed density, indicating improved light interception and canopy development under dense stands. Although excessively high densities may induce intra-specific competition, the 40-seed treatment achieved the best balance between individual plant performance and total yield per unit area. The study concludes that seed density is a critical agronomic factor influencing soybean growth and productivity. An optimal density of approximately 40 seeds per polythene bag (or its field equivalent) is recommended for maximizing biomass and yield in Maiduguri’s semi-arid conditions. This finding provides a practical guideline for farmers to enhance productivity while promoting efficient resource utilization and sustainable agricultural intensification.