Biochemical and yield response of spring wheat to drought stress through gibberellic and abscisic acids

Abstract

Drought stress significantly impacts wheat productivity, but plant growth regulators may help mitigate these effects. This study examined the influence of gibberellic acid (GA3) and abscisic acid (ABA) on wheat (Triticum aestivum L., CV: Giza 171) growth and yield under different water regimes. Using a split-plot design, we tested three drought levels as main plots: normal irrigation (80% field capacity), moderate drought (60% field capacity), and severe drought (40% field capacity). Subplots consisted of GA3 and ABA treatments at 100 and 200 ppm concentrations. Results showed that 200 ppm GA3 treatment enhanced multiple growth parameters under normal irrigation, including plant height (25-30% increase), leaf area (30-35% increase), and reproductive traits (40% increase in number of number of spikes, 35% increase in grains per spike). In contrast, ABA treatment at 200 ppm resulted in reduced plant height (35% decrease) and greater leaf area reduction (40% vs. 20% in control) under drought conditions. GA3 at 200 ppm also improved physiological parameters including catalase and superoxide dismutase activities, protein content, and proline accumulation. These findings demonstrate the distinct roles of GA3 and ABA in regulating wheat growth and stress responses, providing valuable insights for drought management in wheat cultivation.

Keywords: Antioxidant activities; Drought stress; Plant growth regulators; Reactive oxygen species (ROS).

Fig. 1

Pearson’s correlation coefficients among 18 agronomic and physiological traits of crops under varying drought stress conditions and plant growth regulation treatments. PH (plant height), LA (leaf area), DW (dry weight), TN (tiller number), CGR (crop growth rate), SPP (spikes per plant), GN (number of grains per spike), SW (spike weight), TGW (1000-grain weight), GY (grain yield), APX (ascorbate peroxidase), CAT (catalase), SOD (superoxide dismutase), O₂⁻ (superoxide anion), H₂O₂ (hydrogen peroxide), MDA (Malondialdehyde), PrC (proline content), PC (protein content). Positive correlations are indicated by blue, with darker shades representing stronger correlations, while negative correlations are indicated by red, with darker shades also representing stronger correlations. The values in each cell represent the correlation coefficient between two traits, with asterisks indicating the level of statistical significance, *: P ≤ 0.05, **: P ≤ 0.01, and ***: P ≤ 0.001