Effect of Planting Dates on Yield Traits and Components in Sunflower Genotypes

Abstract

A field experiment was conducted during the spring and autumn seasons of 2025 to cultivate sunflower (Helianthus annuus L.) at the experimental fields of Al-Musayyib Technical College, Babil Governorate, within Al-Musayyib Project District, located about 40 km north of the governorate (longitude 44.50° E, latitude 32.50° N). The experiment aimed to study the effect of planting dates on yield traits and their components for several sunflower genotypes.The study included a factorial field experiment with two factors. The first factor consisted of six sunflower genotypes, while the second factor included three planting dates. The experiment was arranged in a Randomized Complete Block Design (RCBD) according to a factorial experiment system.The results of the statistical analysis showed significant differences among genotypes. The genotype Zahrat Al-Iraq recorded the highest mean number of seeds per head (1125.57), whereas Argensun recorded the lowest mean (932.33). Planting dates also showed a significant effect, as the first planting date (20 June) produced the highest mean (1097.60), while the third planting date (10 July) produced the lowest mean (971.43). The interaction treatment (Zahrat Al-Iraq × first planting date) recorded the highest value (1271.70), whereas (Argensun × third planting date) recorded the lowest value (817.70).Seed weight differed significantly among genotypes. Zahrat Al-Iraq recorded the highest mean seed weight (6.96 g), whereas Shumoos recorded the lowest mean (3.81 g). The first planting date resulted in the highest seed weight (5.69 g), while the third planting date produced the lowest value (4.52 g). The interaction (Zahrat Al-Iraq × first planting date) recorded the highest value (7.47 g), whereas (Shumoos × third planting date) recorded the lowest (3.17 g).Significant differences were also observed in plant yield, biological yield, and harvest index. Zahrat Al-Iraq recorded the highest plant yield (76.75 g plant⁻¹) and biological yield (260.57 g plant⁻¹), whereas Shumoos recorded the lowest values (37.90 and 161.90 g plant⁻¹). The first planting date produced the highest values for plant yield (63.40 g plant⁻¹), biological yield (233.40 g plant⁻¹), and harvest index (27.20%). The interaction (Zahrat Al-Iraq × first planting date) recorded the highest harvest index (35.65%), whereas (Argensun × third planting date) recorded the lowest (21.65%).