Características agronômicas de cinco cultivares de soja em quatro densidades populacionais de plantas

Abstract

Soybean is a globally important crop and the main oilseed cultivated worldwide, particularly in Brazil. This study aimed to evaluate the effects of different plant densities on the agronomic traits of soybean cultivars, as well as their performance under distinct population arrangements. The following agronomic traits were quantified: plant height, number of pods per plant, thousand-grain weight, and grain yield. The experiment was conducted in a randomized complete block design with four replications, arranged in a 5 × 4 factorial scheme, consisting of five cultivars (NEO 590 I2X, DM 5961 I2X, CZ 15B99 I2X, CZ 16B12 I2X, and ST 616 I2X) and four plant densities (180,000; 240,000; 280,000; and 320,000 plants ha⁻¹). The cultivars showed different responses to plant density variation. Plant height increased with higher densities, associated with greater intraspecific competition for light. The number of pods per plant and thousand-grain weight tended to decrease at higher populations, indicating assimilate limitation per plant. Grain yield showed a non-linear response, with maximum values generally observed at intermediate densities, suggesting compensation between individual plant components and plant number per area. Responses varied among cultivars, resulting in a significant cultivar × density interaction. Moderate plant densities promoted a better balance between vegetative and reproductive growth, highlighting the need for cultivarspecific population recommendations to maximize yield performance.