Assessing the impact of copper oxide nanoparticles on growth attributes and regenerative potential in date palm (Phoenix dactylifera) micropropagation

Copper oxide nanoparticles (CuO-NPs; 0–40 mg L^–1) were applied in MS medium to evaluate microbial contamination, shoot regeneration, and multiplication in date palm (Phoenix dactylifera L. cv. Barhee). Compared to the untreated control (0 mg L^–1), copper oxide nanoparticles at 10 mg L^–1 eliminated microbial contamination without phytotoxicity, yielding the highest regeneration frequency (88.60%) and maximum shoot number (14.25 shoots jar^–1), whereas 40 mg L^–1 caused 21.6% culture mortality. Supplementation with 10 mg L^–1 CuO-NPs significantly increased shoot nutrient accumulation (N, P, K, Fe, Zn, Cu) relative to the control and other treatments (p ≤ 0.05). Antioxidant enzyme activities (SOD, CAT, POD), total soluble carbohydrates (152.10 mg g^–1 DW), and free amino acids (8.05 mg g–1 DW) reached maximum values at 10 mg L–1, compared to the control, whereas soluble protein declined to 10.40 mg g^–1 DW at 40 mg L–1, dropping below the untreated control. Root induction was highest at 10 mg L^–1 CuO-NPs, while higher concentrations (≥ 20 mg L^–1) suppressed rooting and induced root cellular modifications compared to the control. Plantlets derived from the 10 mg L^–1 CuO-NPs treatment achieved the highest ex vitro acclimatization survival rate (88%). Genetic fidelity analysis using monomorphic RAPD and ISSR markers confirmed genetic stability among regenerated plantlets relative to mother plants and control cultures.