*2.1. Chemicals and Microbial Cultures*

The zinc precursor salts (zinc acetate dihydrate (Zn(OAc)2·2H2O), zinc nitrate hexahydrate (Zn(NO3)2·6H2O), and zinc chloride (ZnCl2)) utilized in the study were analytical grade and purchased from HiMedia (HiMedia Laboratories, Mumbai, India). The reducing agents (sodium hydroxide (NaOH), sodium borohydride (NaBH4)) and other chemicals (ammonium hydroxide or ammonia solution (NH4OH, 25%), and thiourea (NH2CSNH2)) were purchased from Sigma-Aldrich (St. Louis, MO, USA). The analytical

grade complexing-capping agents (starch, cellulose, and bovine serum albumin) were procured from Himedia (Himedia Laboratories, Mumbai, India). The HPLC grade water (CAS No. 7732-18-5, Sisco Research Laboratories Pvt. Ltd., Mumbai, India) was used for the preparation of all the solutions and broth and agar-based media. The broth (CAS No. M403) and agar-based (CAS No. MH096) potato dextrose media were purchased from Himedia (Himedia Laboratories, Mumbai, India).

The maize crop-specific three major test fungal cultures, *Curvularia lunata* (ITCC 7170)*, Fusarium oxysporum* (ITCC 7093), and *Macrophomina phaseolina* (ITCC 5467) were purchased from Indian Type Culture Collection, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, India. The cultures were subcultured on Potato Dextrose Agar media and incubated at 25 ◦C in the dark.
