Impact of silver nanoparticles in alginate gels on seed germination, growth and stress biochemical parameters of cucumber seedlings

Smart horticulture aims to use the emerging technologies to modernise industrial applications and address issues such as productivity, environmental sustainability, and food security. In recent years, scientists have made significant efforts to design the novel methods for horticultural applications with using nanoparticles (NPs) and their composites. The use of silver nanoparticles (Ag-NPs) as growth-modulating and antipathogen agents in horticulture is a promising area of research. However, the current state of knowledge in these fields is still insufficient. The study aimed to assess the impact of alginate gels containing Ag-NPs on the germination of cucumber (Cucumis sativus L.) seeds and the initial growth stage of seedlings. Composites with Ag-NPs were prepared using chemical synthesis, with maltose as the reducing substance and biodegradable polymer, sodium alginate, as the stabilizer. Blotting paper was used to place cucumber seeds on dishes. The seeds were then soaked with diluted test solutions containing Ag-NPs (10 ppm and 20 ppm), as well as treatments with deionized water (negative control) and aqueous sodium alginate solutions (1:5 and 1:10) without silver nanoparticles (positive control). After 8 days, the germination, morphological and biochemical parameters were determined. Seed germination percentage was not affected by alginate gels and 10 ppm Ag-NPs. At a concentration of 20 ppm, Ag-NPs reduced the germination index,as well as length and weight of the root, stem, seedling, when compared to the positive and negative control. The inhibition coefficients for root, stem, and seedling were significantly higher in the treatment group. The application of Ag-NPs at concentrations of 10 and 20 ppm resulted in a decrease in the total antioxidant capacity (TAC), total phenolics (TP), and malondialdehyde (MDA) content in seedling roots compared to the negative control. However, there was an increase in TAC and TP in shoots, but not in MDA. In the roots of the seedlings, the application of Ag-NPs resulted in an increase in catalase (CAT) activity, while ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and superoxide dismutase (SOD) activity was decreased compared to the negative control. In the shoots of the seedlings, CAT, GPX, and SOD activity was higher than in the plant material from the positive control. The application of Ag-NPs had a significant, dose-dependent effect on the investigated parameters of cucumber seedlings. However, it was also observed that sodium alginate without NPs had an impact. Ag-NPs elicit a stronger response in shoot tissues, as reflected by higher TAC and content of TP and MDA, although CAT, GPX, and SOD activity was lower than in roots Composites of sodium alginate with Ag-NPs can be used to shape of cucumber seedling germination performance.