Plant growth stage and melatonin concentration dependency together drive the metal-nutrient dynamics of rice in paddy soil
Creators: name: Menhas, Saiqa
name: Chen, Minjie
name: Jin, Hui
name: Xu, Jiang
name: Zhu, Saiyong
name: Lin, Daohui
Publisher: name: Taylor & Francis
Year: 2025
Subjects: subject: Microbiology
subject: FOS: Biological sciences
subject: Environmental Sciences not elsewhere classified
subject: Chemical Sciences not elsewhere classified
subject: Ecology
subject: Developmental Biology
subject: Plant Biology

description: Foliar application of melatonin shows promise in alleviating oxidative stress in rice, though its influence on metal-nutrient dynamics remains unclear. This study investigated the optimal dosage, timing, and concentration of melatonin for regulating elemental uptake, maintaining redox homeostasis, and managing nutrient dynamics in rice cultivated in cadmium (Cd) and selenium (Se)-enriched soils. Melatonin (50, 200 µM) was applied at vegetative stages: jointing (J) and tillering (T). At the J stage, melatonin improved biomass and photosynthetic pigments but inadequately regulated metal-nutrient dynamics due to incomplete redox homeostasis. However, applying 200 µM melatonin during the T stage significantly (<i>p</i> &lt; 0.05) enhanced Se and iron (Fe) root uptake by 48% and 11%, respectively, while also improving shoot translocation. Notably, M200 reduced chromium (Cr) translocation to shoots by 82% (<i>p</i> &lt; 0.05), thereby increasing root retention capacity. Additionally, 50 µM melatonin reduced root Cd uptake by 54% and increased its translocation to shoots by 53% (<i>p</i> &lt; 0.05), alleviating root toxicity and enhancing the detoxification response in aerial tissues. Melatonin application reduced oxidative stress markers, increased proline levels, and enhanced antioxidative enzyme activities, with M200 at the T stage showing pronounced effects. This strategy represents a promising technological approach for managing elemental homeostasis in rice cultivation. This research is a pioneering investigation into the effects of plant growth stages and melatonin concentrations on metal-nutrient dynamics in rice cultivated in Cd-contaminated paddy soils. The study explores how foliar application of melatonin at different vegetative stages influences the uptake and translocation of toxic elements (Cd, Cr) and beneficial nutrients (Se, Fe). The research uncovers novel insights into the mechanisms of redox homeostasis and elemental regulation. The findings show that melatonin application at the tillering stage, particularly at a concentration of 200 µM L<sup>−1</sup>, enhances antioxidant enzyme activity, mitigates oxidative stress, and promotes a favorable shift in the uptake of beneficial elements while restricting the accumulation of toxic metals in plant shoots. This stage-concentration dependency reveals a new understanding of how precise timing and dosage of melatonin can optimize rice resilience to metal toxicity, thus opening avenues for targeted agricultural interventions in contaminated soils. A promising approach has been developed for managing elemental homeostasis in rice plantsApplying melatonin application at the tillering (T) stage reduces oxidative stress by activating antioxidantsThis approach enhances elemental regulation and promotes plant productivity in the co-presence of Cd and Se in paddy soils A promising approach has been developed for managing elemental homeostasis in rice plants Applying melatonin application at the tillering (T) stage reduces oxidative stress by activating antioxidants This approach enhances elemental regulation and promotes plant productivity in the co-presence of Cd and Se in paddy soils