Increasing the crop quality through enhancement of plant health is a challenging task. In this study, nanoselenium (nano-Se) was sprayed on pepper leaves, and the pepper components were compared to those of selenite. It was found that nano-Se (20 mg/L) resulted in a greater performance of plant health. It increased the chlorophyll and soluble sugar levels, which could activate phenylpropane and branched-chain fatty acid pathways, as well as AT3-related enzymes and gene expressions. These led to an enhancement for the synthesis of capsaicinoids, flavonoids, and total phenols. The nano-Se treatment also significantly promoted the expression of phyto-hormones synthesis genes, and consequently increased jasmonic, abscisic, and salicylic acid levels. Proline pathway-related compounds were increased, which could decrease the malondialdehyde and hydroxyl radical levels in crops. This study shows that nano-Se activated capsaicinoid pathways by enhancing photosynthesis and raising soluble sugar levels. The capsaicinoid contents in peppers were then increased, which consequently promoted the accumulation of secondary metabolites and antioxidants.

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Home processing can reduce pesticide residues in agricultural products, and the common forms of treatment include washing, peeling, blanching, and cooking. In this study, the removal effects of tap water, micron calcium solution, alkaline electrolyzed water (AlEW), ozone water, active oxygen, and sodium bicarbonate on 10 typical pesticide residues in kumquat, cucumber, and spinach were investigated. The residue magnitudes were determined by chromatography–tandem mass spectrometry (GC-MS/MS, LC-MS/MS), combined with the QuEChERS pretreatment method. The model tests showed that the results of soaking and greenhouse were close. The removal effects of pesticide residues in kumquat and cucumber washing by alkaline electrolyzed water with a high pH value, micron calcium, and active oxygen solution were better than other washing solutions. The sodium bicarbonate solution, ozone water, and active oxygen solution were more effective in reducing pesticide residues in spinach than others. Active oxygen solution showed a better removal efficiency for the 10 pesticides than other treatments because of its alkalinity and oxidizability. Among the ten pesticides, pyrethroid pesticides had a higher removal rate. Additionally, chlorpyrifos were the most difficult to remove. For the majority of pesticides, the pesticide residue magnitudes showed a gradual reduction when increasing the washing time. The results indicated that alkaline solutions were effective for the reduction of pesticide residues when the washing time was longer than 15 min.

Selenium nanoparticles (SeNPs) show potential tendency in improving the plant health and food quality. However, the mechanism underlying SeNPs' capability to enhance the biosynthesis of more nutrient components such as flavonoids in crops remains unclear. In this study, it is found that foliar application of SeNPs on celery significantly enhanced the total antioxidant capacity, total flavonoids, total phenols, and vitamin C levels of celery leaves by 46.7, 50.0, 21.4, and 26.7%, respectively. The SeNP application enhanced the biosynthesis of flavonoids, such as apigenin (58.4%), rutin (66.2%), p-coumaric acid (80.4%), ferulic acid (68.2%), luteolin (87.0%), and kaempferol (105.7%). The levels of nutrients such as arginine, tryptophan, and βcarotenes also increased by 147.8, 91.5, and 61.4%, respectively. For other components, the α-linolenic acid (73.8%), 13(S)-hydroxy linolenic acid (65.0%), 12-oxophytodienoic acid (197.5%), and jasmonic acid (72.9%) levels increased in SeNP-treated celery leaves. In conclusion, it was proposed that the mechanism of SeNPs for stimulating nutrient component levels might enhance the antioxidant capacity by regulating the α-linolenic acid pathway, leading to greater biotransformations or accumulation of various nutrients in celery.