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Composite nanomaterials of ZnO/chitosan oligosaccharide (ZnO/COS) and ZnO/chitosan oligosaccharide iodine (ZnO/CTS‐I2) were expected to have effective antimicrobial effects due to the synergistic effects of the components. In this work, we present a method to synthesize ZnO nanoparticles with size of 12.3‐15.0 nm stabled in COS with low molecular weight (Mw) 3,321 g/mol and COS‐I2complex by precipitation of Zn2+with NaOH at pH 9, and then ultrasonic treatment to form ZnO nanoparticles. The UV‐Vis spectra of ZnO/COS and ZnO/COS‐I2composite nanomaterials both appeared absorption peaks typical for surface plasmon resonances of ZnO nanoparticles in solution at 372 and 370 nm, respectively. X‐ray diffraction (XRD) patterns confirmed the formation of ZnO/COS‐I2with wurtzite crystal structure characterized in both materials. The FT‐IR spectra of COS, COS‐I2, nano ZnO/COS, and nano ZnO/COS‐I2were measured. The characteristic peaks for the bonding vibrations of –OH and –NH2groups of ZnO/COS and ZnO/COS‐I2shifted to a larger wavenumber than that of COS. The prepared ZnO/COS and ZnO/COS‐I2nanocomposite materials may have potential for application as antibacterial agents used in medicine, food, and agricultural product preservation, control of harmful microorganisms on plants, and plant growth promotion.

Anthracnose is the severely devastating disease in soybean cultivation. Employing chemical fungicides have been limited in modern agriculture. Currently, the oligochitosan (OC) and OC‐Zn2+complex have been evaluated as efficient fungicides. However, finding a proper method to produce them is still being actively encouraged. This work presents a preparation of 4 % OC solution (Mw ~ 5000 g/mol, the chemical structure unchanged in comparison with the chitosan) by gamma‐ray irradiation combined with a small amount of H2O2. The OC‐Zn2+complex were prepared from OC and Zn2+ion with a molar ratio of 1/0.5 by stirring at ambient condition. The importance characterization of OC‐Zn2+complex were determined by the GPC, UV‐Vis, XRD, FT‐IR techniques and that was evaluated the effectiveness of anthracnose resistance Soybean plants grown in a greenhouse. After the third spraying, a spore suspension of C. truncatumwas introduced. The obtained results indicated that the OC‐Zn2+complex exhibited a significantly stronger disease resistance than that of OC. The disease incidence was of 52.2 % and 33.3 % (compared to 92 % of the control); disease severity was of 35.7 % and 13.8 % (79.9 % in the control) for OC and OC‐Zn2+, respectively. Thus, the OC‐Zn2+complex has the potential for large‐scale production and agricultural application.

Cu2O‐Cu nanoparticles (Cu2O‐Cu NPs) stabilized by alginate have been developed for using as a plant fungicide. The antifungal effect of Cu2O‐Cu NPs against Neoscytalidium dimidiatumfungus causing brown spot disease in dragon fruit plants was investigated. Transmission electron microscopy (TEM) was used to assess the morphology and size of Cu2O‐CuNPs. The average diameter of spherical Cu2O‐Cu NPswas determined to be 5.4 ± 0.4 nm. Furthermore, the Cu2O‐CuNPs stabilized in alginate were also characterized by Fourier transform infrared (FT‐IR) and X‐ray diffraction (XRD) analysis. Especially, the prepared Cu2O‐Cu NPs/alginate showed high antifungal efficiency (~100 %) against Neoscytalidium dimidiatumwith 30 ppm concentration copper. The obtained results showed that Cu2O‐Cu NPs stabilized in alginate have great potential in the development of nanomaterials for plant fungicide applications.

In this study, nano Cu2O-Cu/alginate was synthesised by the chemical reduction of tetra-amminecopper (II) ion complexes soluble using hydrazine as a reducing agent and alginate as a stabiliser. The influence of various copper ion concentrations on particle size and morphology of produced nano Cu2O-Cu/alginate was investigated. The transmission electron microscopy (TEM) analysis and X-ray diffraction (XRD) measurement revealed that the synthesised nano Cu2O-Cu/alginate was mostly composed of Cu2O-Cu in the form of a Cu2O@Cu core-shell structure with particle sizes of 4.2, 5.3, and 8.4 nm for 60, 80, and 100 mM of copper ion initial concentrations, respectively. The obtained nano Cu2O-Cu/alginate exhibited high antibacterial activity against Xanthomonas oryzaepv. Oryzae(Xanthomonas OO). The results showed that the nano Cu2O-Cu/alginate containing 30 mg.l?1of copper ions completely inhibited the growth of Xanthomonas OObacteria, which are responsible for the rice leaf blight disease. Nano Cu2O-Cu/alginate materials can be used as a fungicide to replace toxic agro-chemicals and potentially applied to the development of sustainable agricultural production.