Efficacy of the “Complex-Co” Plant Growth Stimulator and Micronutrient Complex Preparation Against Selected Phytopathogens and Postharvest Spoilage Fungi

Resumé

Background: The growing emphasis on sustainable agriculture has intensified interest in plant growth stimulants derived from natural, non-toxic components. Among these innovations is the micronutrient formulation “Complex-Co,” a tartaric acid–based chelate containing vital elements such as iron (Fe), copper (Cu), zinc (Zn), and boron (B). These micronutrients play key roles in plant physiology, including enzyme function, photosynthesis, growth regulation, and stress tolerance. As a plant growth stimulant, “Complex-Co” holds promise for enhancing plant vigor and strengthening resistance against phytopathogenic and postharvest spoilage fungi, major contributors to reduced crop yields and quality deterioration. 

This study is the first to evaluate the antifungal potential of the multifunctional Complex-Co formulation, which combines copper, zinc, and iron with a biogenic nitrogen-containing tartaric acid derivative. Its unique composition enables simultaneous stimulation of plant growth and inhibition of key postharvest phytopathogens, highlighting its potential for sustainable crop protection and functional-food applications.

Objective: This study aims to investigate the antifungal efficacy of the micronutrient-based plant growth promoter “Complex-Co” against selected phytopathogenic and postharvest spoilage fungi. The research evaluates explicitly the antifungal activity of the formulation at concentrations commonly used in standard plant nutrition practices. Furthermore, the study compares the effectiveness of “Complex-Co” with that of conventional copper-based antifungal treatments.

Materials and Methods: To assess antifungal activity, fungal strains from the genera Alternaria, Aspergillus, Cladosporium, Rhizomucor, and Rhizopus were used as test organisms. Cultures were grown on potato dextrose agar (PDA) in 90 mm × 15 mm Petri dishes and incubated at 25 ± 1 °C. Once the fungal mycelia reached a diameter of 4-5cm, four sterile filter paper disks (6 mm in diameter) were placed approximately 5mm from the edge of the colony. The “Complex-Co” preparation was tested at 10-fold and 100-fold dilutions, alongside a similarly diluted copper-based antifungal formulation for comparison. Each disk was treated with 20 µL of the respective solution. Following treatment, the plates were incubated at 25°C, and fungal growth inhibition was monitored for 2 to 7 days.

Results: The antifungal activity of “Complex-Co” was evaluated against five phytopathogenic fungi: Alternaria alternata, Aspergillus flavus, Cladosporium herbarum, Rhizomucor miehei, and Rhizopus oryzae. At a 1:100 dilution, which corresponds to a Cu²⁺ concentration of 0.125 g/L, inhibition was limited, with zones ≤ 8 mm. At a 1:10 dilution ([Cu²⁺]=1.25 g/L), antifungal activity increased markedly, particularly against Alternaria alternata (13 mm), Aspergillus flavus (15 mm), and Cladosporium herbarum (17 mm). Compared with the commercial fungicide “Avgust Ordan” at equivalent copper concentrations, “Complex-Co” showed comparable or superior inhibition against certain fungi. UV-Visible spectroscopy confirmed the presence of proteinaceous and amino acid components, suggesting their roles in copper chelation, solubility, stabilization, and enhanced antifungal activity. These results demonstrate a concentration-dependent antifungal activity and highlight the potential of “Complex-Co” as a multifunctional plant protection and nutrient formulation.

Conclusion: Micronutrient “Complex-Co” is demonstrating its potential as a broad-spectrum, environmentally friendly alternative to chemical antifungal treatments. The formulation, which includes essential micronutrients, not only promotes plant growth but also enhances resistance to fungal pathogens. This can reduce reliance on synthetic pesticides, improve crop quality, and increase food security, offering a sustainable solution for both agricultural productivity and public health.

Keywords: Chelated Micronutrient, Natural Tartaric Acid, Antifungal Activity, Sustainable Agriculture, Postharvest spoilage fungi.