<![CDATA[Background. Effect of Plant Spacing on Growth, Yield Components, and Yield Stability of Several Soybean (Glycine max L.) Varieties. Soybean is a strategic food commodity in Indonesia, yet domestic production meets only a small portion of national demand due to low farm-level productivity caused by suboptimal variety selection and inappropriate planting spacing, combined with differential variety responses across growing conditions. Aims. This study aimed to evaluate the effects of planting spacing, variety, and their interaction on soybean growth, yield components, and grain yield, and to identify varieties that combine high productivity, consistent performance, and broad adaptability under different planting densities. Methods. A field experiment was arranged in a split-plot design with three replications, using three spacing levels as main plots and four nationally released soybean varieties as subplots. Data were analyzed using analysis of variance, mean comparison tests, and multiple complementary stability and adaptability models. Result. Results showed that plant height and 100-seed weight were determined predominantly by genetic factors, whereas number of seeds per plant and grain yield per hectare exhibited strong variety-by-spacing interactions. Grobogan recorded the highest mean yield and responded well to favorable high-density conditions; Sangga Buana combined broad adaptation with maximum yield at the closest spacing; the large-seeded Dega performed best at intermediate spacing; while Anjasmoro showed the most consistent performance across all conditions despite lower yield potential. Conclusion. It is concluded that agronomic responses to planting spacing are strongly variety-dependent, so no single density is universally optimal for all genotypes. Implementation. These findings provide low-cost, variety-specific spacing recommendations that can immediately raise on-farm soybean productivity, reduce the national yield gap, and support greater food self-sufficiency.]]>
