Enhancing nutritional value and antioxidants in blackberry by foliar potassium sulfate and phenylalanine under soilless cultivation

The aim of this study to enhance the nutritional value and antioxidants in the leaves and fruits of blackberry plants by cultivating them using soilless conducted at Research Station of the College of Agricultural Engineering Sciences-University of Baghdad in the 2023–2024 seasons. Three factors included the first factor: cultivation in organic media of local and imported plant waste: The media included licorice root waste (C3) and coconut husk waste (C2), compared to field soil (C1). The second factor was Folior application of potassium sulfate (S) in concentrations (0, 2.5, 5) g.l⁻¹ and the third factor was foliar applicates with amino acid phenylalanine (A) in concentrations (0, 100, 200) mg. l⁻¹ in factorial experiment as a completely randomized design (R.C.B.D) with three replications. The results indicated the superiority of the treatment with licorice residue medium and phenylalanine at a concentration of 200 mg.l⁻¹ with 2.5 g.l⁻¹ of potassium sulfate (C3A2S1) with the highest concentration of total carotene in the leaves (13.33 mg 100g⁻¹) and the highest concentration of phenols, anthocyanin, and DPPH in the fruits (198.26, 534.5 mg100g⁻¹, 89.41%) respectively. The treatment C3A1S2 excelled with the highest concentration of total carotene and folic acid in the fruits (0.81, 2.62 mg 100g⁻¹) respectively.