Alnus nitida and urea-doped Alnus nitida-based silver nanoparticles synthesis, characterization, their effects on the biomass and elicitation of secondary metabolites in wheat seeds under in vitro conditions

Nano-fertilizers are superior to conventional fertilizers, but their effectiveness has not yet been adequately explored in the field of agriculture. In this study, silver nanoparticles using leaves extract of an Alnus nitida plant were synthesized and further doped with urea to enhance the plant biomass and metabolic contents. The synthesized Alnus nitida silver nanoparticles (A.N-AgNPs) and urea-doped silver nanoparticles (U-AgNPs) were characterized using Scanning Electron Microscopy, Transmission Electron Microscopy, Powder X-ray Diffraction, and Energy Dispersive X-ray. The wheat seeds were grown in media under controlled conditions in the plant growth chamber. The effectiveness of nanoparticles was studied using different A.N-AgNPs and U-AgNPs concentrations (0.75 μg/ml, 1.5 μg/ml, 3 μg/ml, 6 μg/ml, and 15 μg/ml). They were compared with a control group that received no dose of nanoparticles. The plant biomass, yield parameters, and wheat quality were analyzed. The effect of silver nanoparticles and U-AgNPs were examined in developing wheat seeds and their potency in combating biotic stresses such as nematodes, herbivores, fungi, insects, weeds and bacteria; abiotic stresses such as salinity, ultraviolet radiation, heavy metals, temperature, drought, floods etc. In the seedlings, six possible phytochemicals at a spray dose of 6 μg/ml of U-AgNPs were identified such as dihydroxybenzoic acids, vanillic acid, apigenin glucosidase, p-coumaric acid, sinapic acid, and ferulic acid whereas in other treatments the number of phenolic compounds was lesser in number as well as in concentrations. Moreover, various parameters of the wheat plants, including their dry weight and fresh weight, were assessed and compared with control group. The findings of the study indicated that A.N-AgNPs and U-AgNPs act as metabolite elicitors that induced secondary metabolite production (total phenolic, flavonoid, and chlorophyll contents). In addition, U-AgNPs provided a nitrogen source and were considered a smart nitrogen fertilizer that enhanced the plant biomass, yields, and metabolite production.