Nickel Enhances Soybean Growth and Resilience to Iron Stress by Improving Gas Exchange and Antioxidant Metabolism
Elizeu Monteiro Pereira Júnior, Lorena de Souza Cunha, Andreza Sousa Carmo, Ana Clara Lucarini, Ynglety Cascaes Pereira Matos, Allan Klynger da Silva Lobato, Elaine Maria Silva Guedes Lobato*
Núcleo de Pesquisa Vegetal Básica e Aplicada, Universidade Federal Rural da Amazônia, Paragominas, Brazil
* Corresponding Author: Elaine Maria Silva Guedes Lobato. Email: 
(This article belongs to the Special Issue: Plant Growth Regulators (PGRs) and Plant Stress)
Phyton-International Journal of Experimental Botany https://doi.org/10.32604/phyton.2026.072138
Received 20 August 2025; Accepted 24 November 2025; Published online 15 May 2026
Abstract
Nickel (Ni) is an essential metallic micronutrient for optimal plant growth and development, regulator of essential metabolic processes, but its interaction with other essential nutrients can result in differences in the absorption of these nutrients, which can disrupt the ionic balance. The objective of this research was to evaluate the physiological performance and growth of soybean plants subjected to Ni levels applied via soil under Fe (iron) excess, determining the behavior of redox metabolism, gas exchange, and photosynthetic pigments. The experiment was conducted in a completely randomized design with a factorial 2 × 3, with two Fe levels, defined as control Fe (35.7 μM) and excess Fe (357 μM), and three Ni levels (0.2, 1.0, and 3.0 mg kg
−1). Results revealed that Fe toxicity caused significant reductions for leaf dry matter (LDM) and stem dry matter (SDM), but Ni applied to the soil provided increases of 8% and 22% in LDM and SDM. Treatment with toxic Fe caused reductions in photosynthetic pigments in soybean plants. However, 3.0 mg kg
−1 Ni caused increases (
p < 0.05) of 10%, 12%, 10%, and 36% for chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids. Plants treated with 3.0 mg kg
−1 Ni and exposed to Fe stress had boosted the antioxidant system, increasing catalase (14%) and ascorbate peroxidase (16%), while the oxidative damage occasioned by Fe excess in was reduced 6% and 3% in malondialdehyde and hydrogen peroxide, as compared to Fe excess +0.2 mg kg
−1 Ni. Therefore, the Ni application via soil under experimental conditions was found to be a possible mitigator of the phytotoxic effects caused by Fe excess in soybean plants.
Keywords
Biomass;
Glycine max; micronutrient; photosynthesis
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