Clomazone exposure-driven photosynthetic responses plasticity of Pontederia crassipes

• Published in: Environmental science and pollution research international 2024-11, Vol.31 (51), p.61220-61235
• Main Authors: Rodrigues, Bianca Jaqueline Santos, de Moura Silva, Igor Alexander, dos Santos Silva, Marcelo, Posso, Douglas Antonio, Hüther, Cristina Moll, do Amarante, Luciano, Bacarin, Marcos Antonio, Borella, Junior
• Format: Article
• Language: English
• Subjects: (S)-2-hydroxy-acid oxidase; Aquatic environment; Aquatic plants; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; carbohydrate content; Carbohydrates; Carbon dioxide; Carbon dioxide fixation; Chlorophyll; Chlorophyll - metabolism; chlorosis; clomazone; Earth and Environmental Science; Ecotoxicology; Eichhornia crassipes; Environment; Environmental Chemistry; Environmental Health; Epidermis; Exposure; Gas exchange; herbicide application; Herbicides; Herbicides - toxicity; Isoxazoles; leaf epidermis; Leaves; Macrophytes; Metabolism; Oxazolidinones - toxicity; Parameters; Photopigments; Photosynthesis; Photosynthesis - drug effects; Photosynthetic pigments; phytotoxicity; Plant anatomy; Plant Leaves; Plastic properties; Plasticity; Pontederia crassipes; Research Article; species; Stomata; stomatal movement; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 1614-7499; 0944-1344; 1614-7499
• DOI: 10.1007/s11356-024-35319-x

Clomazone is known to contaminate aquatic environments and have a negative impact on macrophytes. However, recent reports suggests that Pontederia crassipes Mart. can withstand clomazone exposure while maintaining growth rates. We hypothesized that this maintenance of growth is supported by photosynthetic plasticity of old leaves (developed before herbicide application), while new leaves (developed after application) exhibit phytotoxic symptoms. To investigate, two experiments were conducted with doses ranging from 0.1 mg L −1 to 0.5 mg L −1 plus untreated controls. Various parameters were measured in old and new leaves over 7, 12, and 15 d post-application, including visual symptoms, chlorophyll index, photosynthetic pigments, chlorophyll fluorescence, gas exchange, glycolate oxidase activity, carbohydrate content, leaf epidermis anatomy, and growth parameters. Clomazone exposure induced chlorosis, particularly in new leaves across all doses. These visual symptoms were accompanied by stomatal closure, restricting gas exchange and CO 2 fixation, leading to reduced photosynthetic rates and carbohydrate synthesis. However, clomazone did not affect old leaves, which maintained photosynthetic activity, sustaining essential metabolic processes of the plant, including reproductive functions. By ensuring high reproductive rates and metabolic continuity, old leaves supported the species' persistence despite clomazone presence.