Evaluation of Biostimulant Effects on Flax Cultivar Giza 12: Quality and Economic Aspects

Two field experiments were carried out during the 2020/2021 and 2021/2022 winter seasons on sandy soil in the Nubaria region of Egypt to assess how foliar biofertilizers influence the productivity and quality of flax (Linum usitatissimum L., cv.Giza 12).Three foliar products were compared: an algae extract, CMS (a condensed molasses soluble obtained from yeast) and an amino acid compound, and their bearing on growth, yield quality, chemical composition, fibre traits, the fatty acid profile and economic return was assessed.Every biofertilizer lifted macronutrient and micronutrient concentrations far above those of the untreated control.The highest gains in nitrogen (115.66% and 121.91%), phosphorus (48.98% and 47.10%) and potassium (45.58% and 29.78%) across the two seasons were obtained with CMS at 5.0 ml L⁻¹, which also strongly increased Fe (226.93% and 29.21%) and Mn (115.82% and 37.42%).Amino acids at 2.0 ml L⁻¹ gave the largest increases in N (77.85% and 94.53%) and Fe (117.63% and 90.86%), whereas the 1.5 ml L⁻¹ rate was most effective for Mn, Zn, fibre percentage, straw protein and fibre length.Algae extract at 1.5 ml L⁻¹ markedly improved nutrient uptake, straw protein (84.46% and 108.0%) and fibre length (13.83% and 38.84%).Treatment also reshaped the fatty acid composition of the seed oil: CMS increased unsaturated fatty acids, particularly linolenic acid at 5.0 ml L⁻¹, while the response to amino acids and algae extract depended on the rate applied.Economically, amino acids at 2.0 ml L⁻¹ produced the highest seed gross return (LE 23,888) and benefit to cost ratio (2.408) in the first season, whereas CMS at 7.5 ml L⁻¹ gave the highest straw gross return (LE 53,445) and benefit to cost ratio (5.545) in the second season.Taken together, foliar biofertilization, and in particular CMS at 5.0 ml L⁻¹ alongside amino acids at 1.5 to 2.0 ml L⁻¹, emerged as an effective route to better nutrient status, fibre quality, oil composition and profitability in flax grown on sandy soil.