Role of Sowing date and Gibberellic Acid Spray on Growth and Quality Traits of Faba Bean

• Ameer Sadiq Obaid1 Razzaq Lifta Attiya2

  Author

     A field experiment was carried out to study the effect of growth regulator foliar spray and thermal accumulation during the winter season of 2024-2025 on a Spanish variety of Faba bean (Vicia faba L.) 'Luz de Oton' Cv. The experiment was carried out on silty clay soil at Al-Mahnawiyya Extension Farm belonging to Babylon Training and Extension Center (32.61°N, 44.30°E). The study was conducted using Randomized Complete Block Design (RCBD) with a split plot arrangement and three replications. The purpose of the study was to examine the effect of thermal accumulation and gibberellic acid (GA₃) spray on Faba bean growth and quality. The treatments in the main plot were four sowing dates: 1 October, 15 October, 1 November and 15 November (D1, D2, D3 and D4, respectively). Subplots were assigned six concentrations of gibberellic acid: 0, 50, 100, 150, 200, and 250 mg L^-1, designated as G0, G1, G2, G3, G4, and G5, respectively. The vegetative growth and qualitative traits were measured at physiological maturity. In the branching stage foliar application of gibberellic acid (GA3) was applied to the vegetative parts according to prescribed treatments. The control treatment was sprayed with distilled water only. The results indicated that the highest average of plant height, branch numbers and chlorophyll content (73.11 cm),(8.83 branch plant -1), and (47.09 SPAD) were recorded at the second planting date (D2). On the other hand, the first planting date (D1) has the highest averages of protein percentage, total carbohydrate and thermal accumulation (GDD)(32.278%, 49.078%, 1089.10∘C⋅d). Moreover, the highest average of most of the studied traits were recorded when spraying plants with gibberellic acid at 250 mg L⁻¹ (G5). Planting dates by gibberellic acid concentrations interaction significantly affected some traits; In this respect, interaction treatment D1G5 led to the highest protein and carbohydrate percentages (37.829%, 52.606%). But the interaction was not significant for other traits.

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