Interactive effects of silica nanoparticles and putrescine on morphophysiological and biochemical performance in stock (Matthiola incana L. 'Pilaster White').

Stock (Matthiola incana L. 'Pilaster White') is an economically important ornamental species whose commercial value depends largely on vigorous vegetative growth, high floral quality, and extended vase life. Silica nanoparticles (SiO₂ NPs) and putrescine have individually been reported to improve plant growth and physiological performance through different mechanisms; however, information regarding their interactive effects in stock remains limited. Therefore, this study evaluated the individual and interactive effects of foliar-applied SiO₂ NPs and putrescine on the morphophysiological, biochemical, and vase life of stock plants. A factorial experiment based on a completely randomized design was conducted using four SiO₂ NP concentrations (0, 50, 100, and 200 mg L⁻¹) and three putrescine concentrations (0, 1.5, and 3 mM). Foliar application of SiO₂ NPs and putrescine, particularly at appropriate concentrations and combinations, improved vegetative growth, biomass accumulation, floral quality, and vase life compared with the untreated control. Among the tested combinations, 1.5 mM putrescine combined with 50 mg L⁻¹ SiO₂ NPs resulted in the greatest improvement across most evaluated traits. This treatment was associated with increased chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, soluble sugar, protein, and anthocyanin contents, suggesting improved photosynthetic capacity and metabolic status. Overall, the results demonstrate that the interactive effects between SiO₂ NPs and putrescine improve plant growth, floral quality, and vase life in stock under greenhouse conditions and may represent a promising biostimulant strategy for enhancing the commercial quality of ornamental plants.