Mitigating effect of γ-aminobutyric acid and gibberellic acid on tomato plant cultivated in Pb-polluted soil

Abstract

Soil heavy metal pollution poses a significant environmental risk to human health and plant growth. Gibberellic acid (GA) and γ-aminobutyric acid (GABA) are effective methods for resolving this issue. GA regulates growth mechanisms such as seed germination, flowering, and stem elongation. Plants use GABA, a signaling molecule, to control physiological processes, growth, and responses to stress. This substance plays a crucial role in the interactions between hormones and plant defense, as evidenced by its effects on photosynthesis, food absorption, and stomatal behavior. The study aimed to determine how GABA and GA amendments affected tomato plants under no toxicity and Pb toxicity. The study included four treatments (0, GA, GABA, and GA + GABA) in four replications following a completely randomized design. Notably, the GA + GABA treatment led to considerable enhancements in fresh weight (88.98%), dry weight (68.28%), shoot length (39.98%), and root length (115.43%) compared to the control under Pb toxicity. Moreover, GA + GABA treatment significantly increased tomato chlorophyll a (161.72%), chlorophyll b (93.33%), and total chlorophyll content (112.45%) under Pb stress toxicity, confirming the effectiveness of GA + GABA treatment. In conclusion, GA + GABA is recommended as the best amendment to mitigate Pb stress in tomato plants. Our findings have broader implications for GA + GABA application, offering a potential technology to enhance sustainable crop production by improving plant growth and yield in Pb-contaminated soils. More investigations are suggested at field levels under different agroclimates on different crops for the declaration of GA + GABA as the best amendment for alleviating different heavy metal pollutions and sustainable agriculture productions.

Keywords: Gibberellic acid; Growth attributes; Lead toxicity; Plant health; Restoration; γ-Aminobutyric acid.

Fig. 1

The study examines the effects of treatments on tomato plants grown in non-toxic and Pb-toxic environments in terms of the number of leaves (A), number of roots (B), and leaf area (C). Different letters on bars that reflect the average of four replicates indicate significant changes in the Tukey test at p < 0.05.

Fig. 2

The study examines the effects of treatment on tomato grown under Pb toxicity and no toxicity conditions in terms of chlorophyll a (A), chlorophyll b (B), and total chlorophyll (C). Different letters on bars that reflect the average of four replicates indicate significant changes in the Tukey test at p < 0.05.

Fig. 3

Effect of treatments on carotenoids (A), anthocyanin (B), and lycopene (C), of tomato cultivated under no toxicity and Pb toxicity. Different letters on bars that reflect the average of four replicates indicate significant changes in the Tukey test at p < 0.05.

Fig. 4

The study examines the effects of treatments on tomato plants grown under no toxicity and Pb toxicity, focusing on total protein (A), total soluble sugar (B), total amino acids (C), and flavonoids (D). Different letters on bars that reflect the average of four replicates indicate significant changes in the Tukey test at p < 0.05.

Fig. 5

The study examines the effects of treatments on tomato grown under no toxicity and Pb toxicity in terms of MDA (Malondialdehyde) (A), APX (Ascorbate peroxidase) (B), and H₂O₂ (Hydrogen peroxide) (C). Different letters on bars that reflect the average of four replicates indicate significant changes in the Tukey test at p < 0.05.

Fig. 6

The study examines the effects of POD (Peroxidase) (A), SOD (Superoxide dismutase) (B), and CAT (Catalase) (C) treatments on tomatoes grown under Pb toxicity and without toxicity conditions. Different letters on bars that reflect the average of four replicates indicate significant changes in the Tukey test at p < 0.05.

Fig. 7

Cluster plot convex hull for lead (Pb) toxicity levels (A), treatments (B), and hierarchical cluster plot (C) for studied attributes.

Fig. 8

Pearson correlation for studied attributes.