Preparation of radiolysis‐degraded oligochitosan, oligochitosan‐Zn²⁺ complex and their induced effect against Anthracnose on soybean plants

<jats:title>Abstract</jats:title><jats:p>Anthracnose is the severely devastating disease in soybean cultivation. Employing chemical fungicides have been limited in modern agriculture. Currently, the oligochitosan (OC) and OC‐Zn<jats:sup>2+</jats:sup> 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 H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>. The OC‐Zn<jats:sup>2+</jats:sup> complex were prepared from OC and Zn<jats:sup>2+</jats:sup> ion with a molar ratio of 1/0.5 by stirring at ambient condition. The importance characterization of OC‐Zn<jats:sup>2+</jats:sup> 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 <jats:italic>C. truncatum</jats:italic> was introduced. The obtained results indicated that the OC‐Zn<jats:sup>2+</jats:sup> 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‐Zn<jats:sup>2+</jats:sup>, respectively. Thus, the OC‐Zn<jats:sup>2+</jats:sup> complex has the potential for large‐scale production and agricultural application.</jats:p>