Response of Flax (Linum usitatissimum L.) Cultivars to Nitrogen Rates and Foliar Fertilization: B- Impacts on Oil, Fiber Yield, and Soil Fertility

Abstract

Flax (Linum usitatissimum L.) is a dual-purpose crop cultivated for seed oil and fibre, and its productivity depends on cultivar performance and balanced nutrient management. A field experiment was conducted during two winter seasons (2022/2023 and 2023/2024) at Etay El-Baroud Agricultural Research Station, Egypt, using a split-split plot design with three replications. Two flax cultivars (Giza 11 and Giza 12) were assigned to the main plots, two nitrogen rates (75% and 100% of the recommended dose; 37.5 and 50 kg N fed⁻¹) to the sub-plots, and eight foliar fertiliser treatments to the sub-sub-plots: control, Fe, Si, S, Si×S, Si×Fe, S×Fe, and Si×S×Fe. Foliar sprays were applied at 50, 60 and 85 days after sowing. The combined analysis showed that Giza 11 recorded higher seed protein content (16.86%), whereas Giza 12 produced higher oil yield (105.85 kg fed⁻¹) and fibre yield (69.71 kg fed⁻¹). Increasing nitrogen to 100% of the recommended dose improved protein, oil and fibre yields. Among foliar treatments, Si×Fe recorded the highest mean protein yield (102.94 kg fed⁻¹), Fe produced the highest oil percentage (24.41%) and oil yield (119.61 kg fed⁻¹), and Si×S×Fe gave the highest fibre percentage (12.40%) and fibre yield (70.68 kg fed⁻¹). The results indicate that cultivar-specific nutrient management can improve flax yield, quality and post-harvest soil fertility.