Effect of Integrated Nitrogen and Bio-fertilization on Growth, Yield and Oil traits of Sunflower (Helianthus annuus L.)

• Raghad Amjad Abdulhameed and Waleed Khalid Shahatha Al-Juheishy

  Author

A field experiment was conducted during the spring and autumn growing seasons of 2025 in the 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 characteristics 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 for both growing seasons. The combination of 35 kg N ha^-1 + Azotobacter resulted in the highest average plant height, disc diameter, and oil percentage for both seasons, while the combination of 20 kg N ha + Azotobacter resulted in the highest average chlorophyll content index. Cultivars significantly affected all studied traits. The Taqah-1 cultivar recorded the highest values ​​for plant height, number of leaves, disc diameter, 1000-seed weight, seed yield, oil percentage, and oil yield for both growing seasons, while the Aqmar cultivar  recorded the highest value for chlorophyll content index for both growing seasons. There was a significant interaction between the 35 kg N ha^-1 + Azotobacter combination and the Taqah-1 cultivar  in plant height and oil percentage and 1000-seed weight for both growing seasons.

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