Impact of Foliar Spraying of 5-Aminolevulinic Acid and Nano-Zinc Oxide on Leaf Chemical Composition and Pigment Content of Dwarf Bougainvillea 'Jewel Pink'

• Bushra Alawi Hussain Khalaf1 and Zeyad Mohammed Abdulrazzaq2

  Author

The study was carried out in the greenhouse of the Horticulture Department/University of Anbar from October 2025 to April 2026 to identify the effect of foliar application of the growth regulator 5-ALA and Nano-ZnO on increasing the chemical content of the leaves and flower clusters of Bougainvillea spp. Jewel pink plants. The study included spraying the foliage in the early morning with 5-ALA [control treatment: (0, 25 , 50 and 100 mg L^-1) and Nano-ZnO (0, 50  and 100 mg L^-1). The experiment was designed according to RCBD with three seedlings and three replicates. Spraying dwarf Bougainvillea seedlings with the growth regulator 5-ALA at a concentration of 50 mg L^-1 (A₃) resulted in a significant improvement in chemical growth characteristics. This treatment exhibited the highest levels of beta-carotene content in inflorescences (2.93 mg g^-1 FW) and higher levels of total chlorophyll (2.17 mg g^-1 FW), nitrogen (2.25%), phosphorus (0.49%), potassium (2.09%), carbohydrates (27.24%), and zinc (66.36 mg kg^-1) in the leaves. In contrast, the control treatment A1 (0 mg L^-1) showed the lowest significant improvements in these growth characteristics. Furthermore, spraying the foliage with Nano-ZnO (ZnO-NPs) at a concentration of 75 mg L^-1 (Z₂) also demonstrated a significant improvement in the same chemical characteristics, with values of 2.66 mg g^-1 and 2.06 mg g^-1 FW, as well as 2.08, 0.46, 2.00, 26.03%, and 61.98 mg kg^-1, respectively. While the rates were reduced to the lowest possible level when treated with distilled water (the control treatment), the spray treatments of 50 mg L^-1 of 5-ALA and 75 mg L^-1 of Nano-ZnO (A₃Z₂) excelled in chemical growth characteristics, except for leaf phosphorus and carbohydrate content. In comparison, A₁Z₁ (0 mg L^-1) resulted in the least significant differences in these same characteristics.

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