Effect of Azotobacter Inoculation on Growth, Yield, and Oil Quality of Sunflower (Helianthus annuus L.) Cultivars

Abstract

A field experiment was conducted during the spring and autumn seasons of 2025 in Al- Jalyukhan region to study the effect of five combinations of biofertilizers and nitrogen fertilizers (80 kg N ha⁻¹, 65 kg N ha⁻¹ + Azotobacter, 50 kg N ha⁻¹ + Azotobacter, 35 kg N ha⁻¹ + Azotobacter, and 20 kg N ha⁻¹ + Azotobacter) and three sunflower cultivars (Aqmar, Banam, and Taqah-1) on growth traits and yield. The experiment was conducted as a split-plot factorial experiment with a randomized complete block design (RCBD) and three blocks. The results showed significant differences between the combinations in most of the studied traits in both seasons. The combination of 35 kg N ha-1 + Azotobacter gave the highest average plant height, number of seeds per disc, seed yield, and oil percentage in both seasons, while the combination of 50 kg N ha-1 + Azotobacter gave the highest average disc diameter. Cultivars significantly affected all studied traits. Taqah-1 cultivar recorded the highest values for plant height, stem diameter, number of seeds, 1000-seed weight, seed yield, oil percentage, and oil yield in both seasons. There was a significant interaction between the 35 kg N ha-1 + Azotobacter combination and Taqah-1 cultivar in plant height, oil percentage for spring season, number of seeds per disc, and 1000-seed weight for both seasons.