Introduction.

The use of microbial consortia (CM) combined with adequate plant densities (DP) can be a viable and friendly alternative to increase sustainable sunflower (Helianthus annuus L.) production. Objective. To determine the individual and combined effects of microbial consortia and plant densities on sunflower growth and yield under water-deficit conditions. Materials and methods. The study was conducted between January and May 2024 in Sancti Spíritus, Cuba. Under field conditions, an experiment was established using a split-plot arrangement in a randomized block design with three replications. The main plots consisted of two DP (20,000 and 40,000 plants/ha), and the secondary plots of three CM concentrations (0, 100, and 200 mL m-2). Results. Individually, DP and CM directly influenced sunflower growth and yield. The DP of 40,000 plants/ha favored plant height, leaf area index, percent of full seeds, seed mass per head, and yield. The DP of 20,000 plants/ha increased leaf area, chlorophyll content, head diameter, and total and full seed per head. The concentrations of 100 mL m-2 of CM stimulated plant growth and yield in both densities compared to the treatments without CM and with 200 mL m-2 of CM. Conclusions. The combination of a density of 40,000 plants/ha and inoculation with 100 mL m-2 of CM could be considered a local, viable, important, and friendly strategy to increase sustainable sunflower production under low-rainfall conditions.