Utilizing the coordination effect of the mild hydration method to promote the complexation of artificial fulvic acid with iron to alleviate the yellowing of peanut leaves

Peanut leaf yellowing severely affects peanut (Arachis hypogaea L.) growth and yield. Iron (Fe) deficiency or obstacles in Fe absorption and utilization are key factors causing this yellowing. This study innovatively applied mild hydration to boost coordination between artificial fulvic acid (AFA) and Fe. Successfully prepared artificial fulvic acid iron (AFA-Fe) with good stability and bioavailability. Single-factor experiments revealed optimal parameters. When the mass ratio of AFA to FeSO4 is 4:1, the pH is 5, and the reaction temperature is 60 °C, the maximum yield of AFA-Fe can reach 24.65 % after 3 h of reaction. Structural analysis showed the main structure of AFA-Fe is extremely similar to that of AFA. Its carboxyl and hydroxyl groups enable Fe2 + to function more effectively. Field experiments demonstrated that AFA-Fe, as an Fe fertilizer, effectively promotes chlorophyll synthesis and transformation in peanut leaves. This significantly alleviated peanut leaf yellowing. It also increased peanut yield to 5106.77 kg/hm2 and kernel yield to 4062.01 kg/hm2. This work provides a efficient and practical method to solve peanut leaf yellowing. It also offers new and effective strategies for agriculture green development.