Physiological and biochemical responses of Vicia faba L. to folic acid treatments and their relation to Aphis fabae infestation

Abstract

Background: This study investigated the effects of foliar-applied folic acid (FA) on the growth and biochemical responses of faba bean (Vicia faba L.) under black bean aphid (Aphis fabae) infestation.

Objective: This study aimed to evaluate the effect of foliar-applied folic acid on the growth, biochemical composition, and antioxidant defense system of faba bean (Vicia faba L.) and to determine its relationship with black bean aphid (Aphis fabae) infestation.

Methods: Faba bean plants were treated with folic acid at concentrations of 0, 50, 100, and 150 mg/L under greenhouse conditions. Growth parameters, photosynthetic pigments, metabolites, and antioxidant enzyme activities were measured, and aphid infestation trials were conducted to assess plant resistance responses.

       Folic acid significantly improved plant growth, photosynthetic pigments and biochemical composition, with the highest concentration (150 mg/liter) producing the strongest effect. Aphid infestation markedly reduced biomass and pigment content; FA at 100–150 mg/L partially restored these parameters. FA treatments also increased secondary metabolites and antioxidant enzyme activities, infected plants showed a strong defense response, indicating a priming effect against biotic stress.

Results: Folic acid application significantly improved growth parameters of both healthy and aphid-infested green bean plants, with 150 mg/L producing the highest fresh and dry weights. It partially alleviated aphid-induced stress by restoring growth performance compared with untreated infested plants. Treatment also enhanced plant water status and height, indicating improved physiological activity and hormone-like effects. These findings support the potential of folic acid as a biostimulant for sustainable crop productivity and stress tolerance.

Novelty of the study: This study demonstrates a dual role of folic acid as both a growth-promoting biostimulant and defense-promoting agent against Aphis fabae in Vicia faba. Unlike previous studies focused primarily on abiotic stress, this work integrates physiological, biochemical and insect-related responses, supporting folic acid as a sustainable tool to increase crop productivity and resistance under biotic stress.

Conclusion: Folic acid acts as an effective biostimulant that improves growth, photosynthetic efficiency and antioxidant defense in faba bean while reducing aphid-induced damage. These findings support its use as a sustainable strategy to enhance pest tolerance and increase crop productivity.

Keywords: Vicia faba, folic acid, Aphis fabae, antioxidant enzymes, metabolites, plant resistance.