Zinc oxide and silver effects on the growth, pigment content and genetic stability of chrysanthemums propagated by the node culture method

This article describes benefits of the application of zinc oxide submicron particles (ZnO SMPs), zinc oxide nanoparticles (ZnO NPs) and ZnO NPs combined with silver NPs (ZnO + Ag NPs) in chrysanthemum micropropagation. Single node explants of Chrysanthemum × morifolium (Ramat.) Hemsl. ‘UTP Burgundy Gold (UBG)’ and ‘UTP Pinky Gold (UPG)’ were inoculated on the Murashige and Skoog (MS) medium and treated with 100 mg · L⁻¹, 200 mg · L⁻¹, or 400 mg · L⁻¹ ZnO SMPs, ZnO NPs (1.5% H₂O), ZnO NPs (6% H₂O), ZnO + 0.1% Ag NPs (1.5% H₂O), ZnO + 0.1% Ag NPs (6% H₂O), ZnO + 1% Ag NPs (1.5% H₂O) and ZnO + 1% Ag NPs (6% H₂O). Generally, the tested materials stimulated the growth and development of plantlets. In ‘UBG’, the most prominent treatments affecting increases in the number of leaves, micropropagation coefficient, shoot length and shoot FW/DW weight included 400 mg · L⁻¹ ZnO SMPs and 100 mg · L⁻¹ ZnO NPs (6% H₂O). In ‘UPG’, the treatments with 200 mg · L⁻¹ ZnO + 0.1% Ag NPs (6% H₂O) and 200 mg · L⁻¹ ZnO + 1% Ag NPs (6% H₂O) were the most successful. The latter treatment stimulated an intensive development of root systems in the two studied cultivars. High values of leaf area, perimeter and width were reported in both cultivars for 400 mg · L⁻¹ ZnO + 1% Ag NPs (6% H₂O). As compared to the control, the treated plants were characterised by a similar or, most often, lower content of chlorophylls and carotenoids. The randomly amplified polymorphic DNA (RAPD) and start codon targeted polymorphism (SCoT) marker system analyses of the 400 mg · L⁻¹ ZnO SMPs/ZnO NPs/ZnO + Ag NPs-treated chrysanthemums confirmed their genetic fidelity with the control plants. The obtained results can be implemented in the commercial large-scale production of chrysanthemums.