Response of Flax (Linum usitatissimum L.) Cultivars to Nitrogen Rates and Foliar Fertilization: Impacts on Seed Yield and its Component

Abstract

Flax is an important dual-purpose crop cultivated for fiber and seed production, but its productivity depends strongly on cultivar selection and nutrient-management practices. This study evaluated the response of two flax cultivars to nitrogen rates and foliar applications of silicon, sulphur and iron under field conditions. The experiment was conducted during the 2022–2023 and 2023–2024 winter seasons at Etay El-Baroud Agricultural Research Station, Egypt, using a split-split plot design. The main plots included two cultivars, Giza 11 and Giza 12, while nitrogen fertilisation at 75% and 100% of the recommended dose was assigned to sub-plots. Foliar treatments containing Fe-EDTA, potassium silicate and potassium thiosulphate were applied individually and in combinations at 50, 60 and 85 days after sowing. The results showed that capsule number, seed yield, straw yield, technical length and mineral content were influenced by interactions among cultivar, nitrogen rate and foliar treatment. Giza 12 generally showed higher seed productivity, with seed yield ranging from 0.43 to 0.66 Mg fed⁻¹, whereas Giza 11 ranged from 0.43 to 0.57 Mg fed⁻¹. Combined foliar treatments, especially Si × S, Si × Fe and S × Fe, often produced better yield related responses than individual applications. The findings indicate that cultivar-specific integration of nitrogen and foliar nutrient management can improve flax productivity under the tested conditions.