Informative title: Development of lighting intensity approach for shoot proliferation in Phalaenopsis amabilis through combination with silver nanoparticles

Abstract This experiment was designed to improve shoot proliferation by optimizing light intensity and reducing the potential effects of ethylene such as explant yellowing, unexpanded leaf and narrow shoots. For this purpose, shoot tips as explants were cultured in to the Murashige and Skoog medium with major salts at half‐strength supplemented with silver nanoparticles concentrations (0, 5, 10, 20, 40 µM AgNPs) which were then exposed to three different light intensities (40, 80, 160 µmol m−2 s−1) for a period of three months. Morphological (leaf number, dry and fresh weight of regenerants), biochemical and oxidant/antioxidant responses of regenerants were quantified. According to the results, low light intensity (40 µmol m−2 s−1) stimulated the shoot proliferation of Phalaenopsis and the effects of 5 µM AgNPs on shoot number while showing the maximum fresh and dry weight. It was also observed that chlorophyll, carbohydrate and protein content, enzymatic activity (superoxide dismutase and catalase), H2O2 generation, medium browning and phenolics content improve with higher light intensities (80 and 100 µmol m−2 s−1). Higher AgNP concentrations reduced shoot proliferation, dry weight, and soluble proteins. The most effective combinatorial treatment for the shoot proliferation stage of Phalaenopsis was determined to be 5 µM AgNPs and 40 µmol m−2 s−1.