Indole-3-acetic acid improves growth, physiology, photosynthesis, and ion balance under cadmium stress in Sorghum bicolor.

Bibi A, Ullah MS, Mahmood A, Shahzad M, Javaid MM, Nadeem MA, Altihani FA, Hashem M, Qari SH

Published: 30 September 2025 in Scientific reports
Keywords: Sorghum bicolor (L. Moench), Antioxidants, Cadmium stress, Indole-3-acetic acid (IAA), Ionic parameters, Morphophysiological parameters, Reactive oxygen species (ROS)
Pubmed ID: 41028201
DOI: 10.1038/s41598-025-10900-7

This research examines the influence of exogenous indole-3-acetic acid (IAA) on growth parameters and cadmium stress resistance in Sorghum bicolor (L. Moench). The plants were grown in pots, each filled with 4.5 kg of sand. After 21 days, root treatment with indole-3-acetic acid (IAA) was applied using five concentrations (0, 50, 100, 150, and 200 µM) under three cadmium (Cd) levels (0, 40, and 80 ppm). Applied Cadmium stress significantly reduced plant growth, with reductions in root length (12.73-15.88%), shoot length (17.60-19.25%), and plant height (10.62-14.88%). All growth parameters were improved with the application of 200 µM IAA, increasing root length (20.25-28.25%), shoot length (35.68-45.68%), and plant height (20.37%). The highest level of cadmium stress (80 ppm) was the most detrimental, while the 200 µM IAA treatment produced the most favorable results. Under cadmium stress, IAA application reduced the uptake of Na+, K+, and Ca2+ ions by 7.69-9.52%, 3.70-7.31%, and 6.66-7.69%, respectively, as well as Cd2+ by 2.50-5.26%. Despite these reductions, IAA application significantly enhanced antioxidant activities, including catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD). At 200 µM IAA, antioxidant enzyme activities were increased by 4.65% (SOD), 8.82% (POD), 10.06% (CAT), and 17.9% ascorbate peroxidase (APX). The treatment also boosted chlorophyll content (17.46-22.85%), while reducing oxidative stress markers such as H2O2 (29.4-40.8%) and malondialdehyde (38.9-42.1%). These findings suggest that IAA effectively mitigates cadmium-induced stress by improving growth parameters and physiological responses. Future research should explore the molecular mechanisms underlying IAA-mediated cadmium stress alleviation.