Preparation of AgNPs/SiO₂/Oligochitosan by Irradiation Method for Use as a Phytoalexin Stimulation Fertilizer in Soybean Plants

Abstract

    In this study, a silver nanoparticles dopped on silica microparticles and stabilized in oligochitosan (AgNPs/SiO₂/Oligochitosan) was successfully prepared by γ-ray irradiation and evaluated its phytoalexin stimulation and growth promotion effects on soybean plants. The results showed that the efficiency and purity of silica microparticles synthesized from rice husk by sol - gel method were about 10.7 and 98.34 %, respectively. Chitosan with molecular weight (Mw) approximately 47.8 kDa was also successfully prepared by γ-ray irradiation combined with 2 % H₂O₂ at a dose of 15 kGy. The AgNPs/SiO₂/Oligochitosan product was successfully prepared from the mixture of 100 ppm AgNO₃, 2 % SiO₂ and 5 % low Mw chitosan by irradiation at 4 kGy. The treatment of AgNPs/SiO₂/Oligochitosan product at 0.4 % not only increased the germination rate, reduced the average germination time, increased the biomass and enhanced chitinase activity in soybean sprouts but also strongly promoted the growth and significantly the phytoalexin stimulation in 35-day-old soybean plants. The above results demonstrated that the AgNPs/SiO₂/Oligochitosan product prepared by γ-ray irradiation method has potential applications in high-tech agricultural production.