Metabolic Regulations of Glycine max Induced by Potassium Nanoparticles Under Simulated Salinity Conditions: A...

Crop productivity is a major concern in modern agriculture due to fluctuating environmental conditions, such as salinity. This study aims to explore the green-synthesized potassium nanoparticles (K-NPs) mediated metabolic regulations, including improved ion homeostasis, photosynthetic efficiency, and antioxidative defense mechanisms in soybean (Glycine max var. Soygold) under salinity stress. The K-NPs were green synthesized using the leaf extract of Cordia myxa L. and then characterized using UV-Vis spectroscopy, high-resolution transmission electron microscopy (HRTEM), and zeta potential. Soybean seedlings were treated with 0, 30, 60, and 90 mg L^-1 of K-NPs along with salinity stress of 30, 60, and 90 mg L^-1 NaCl at 3, 7, and 14 days of plant growth. After the treatments, morphological, biochemical and antioxidant activities were measured. The plant root/shoot lengths were enhanced by 9% and 59%, respectively, while the number of leaves was increased by 32%, fresh biomass by 84%, and dry weight by 105% under K-NPs treatments compared to control. K-NPs at 30 and 60 mg L^-1showed non-significant results under 60 and 90 mg L^-1 NaCl concentrations, but highly significant results were observed at 90 mg L^-1 K-NPs under 30 and 90 mg L^-1 NaCl concentrations. The 90 mg L^-1 K-NP concentration improved the root/shoot lengths of soybean seedlings by 33% and 132%, respectively. The number of leaves were increased by 38%, the plant fresh biomass by 22%, and dry weight by 133% as compared to lower concentrations under salinity stress. Furthermore, phenolic contents, secondary metabolites, and ionic homeostasis were also increased in the presence of 90 mg L^-1 K-NPs under 90 mg L^-1 NaCl salinity stress. When exposed to salt stress, K-NPs treatment increased antioxidant enzymes (SOD, CAT, and POX) more than the salt stressed control. Taken together, these results suggest that K-NPs are effective nanomaterials for plant growth enhancement by regulating the defense mechanisms of soybean to cope with salt stress conditions. The findings could help in the designing and optimization of nanomaterial-based fertilizers in order to achieve sustainable agriculture.