Phytotoxicity assessment of isoproturon on growth and physiology of non-targeted aquatic plant Lemna minor L. - A comparison of continuous and pulsed exposure with equivalent time-averaged concentrations

Growth inhibition and recovery patterns of common duckweed Lemna minor L. after repeated exposure to isoproturon

“…In the previous study, we have demonstrated that although L. minor shows high potential for growth recovery after single pulse exposure to isoproturon, significant physiological changes were detected in plants even at the end of the recovery phase such as significantly reduced concentration of proteins and photosynthetic pigments, as well as significantly induced levels of biomarkers for oxidative stress and activities of antioxidative enzymes (Varga et al 2019). These findings suggest that although growth has recovered, the overall physiological recovery process has not been completed even five days after single exposure to isoproturon and increased toxic effects are expected upon subsequent exposure events.…”

“…In the previous study, we have observed that a single 2-or 3-days long exposure to isoproturon had a lesser overall effect on the growth of common duckweed compared to continuous treatment with equivalent TWA concentrations. Nevertheless, these short exposures induced significant physiological changes such as the reduced concentration of proteins and photosynthetic pigments, as well as increased damage to the lipids due to significant accumulation of hydrogen peroxide in the tissue (Varga et al 2019). Moreover, these significant changes were observable even after 4 and 5 days of the recovery period, in which growth endpoints indicated complete recovery.…”

“…Therefore, the present study aimed to investigate the effects of repeated exposures to isoproturon on growth, as a standard endpoint, and recovery potential of common duckweed, Lemna minor L. Tests were performed as a modified standard growth inhibition test in three repeated treatment cycles with isoproturon in a concentration range below reported 7-day effective concentration (EC 50 ) causing 50% inhibition of frond number growth rate (Knežević et al (2016): EC 50 = 220 µg L −1 ; Tunić et al (2015): EC 50 = 230 µg L −1 ). L. minor, a standard photosynthetic nontargeted aquatic organism has been chosen for this study due to favorable traits that enable population-level studies in laboratory conditions and a high potential for recovery from a single exposure to isoproturon (Varga et al 2019) and other types of herbicides (Wilson and Koch 2013;Burns et al 2015;Tunić et al 2015). The specific study objectives were (1) to compare the effects of repeated isoproturon exposure on the growth of L. minor in two time-variable exposure scenarios with the effects observed in a standard growth inhibition test with continuous exposure (to enable direct comparison of effects from different time-variable exposure scenarios TWA approach was used), (2) to assess the overall effects of multiple exposures and expected carry-over effect on plant biomass production and (3) to discuss comparability of standard toxicity endpoints in modified laboratory test simulating repeated exposures with the recovery phase.…”

Bensulfuron-Methyl, Terbutylazine, and 2,4-D Butylate Disturb Plant Growth and Resistance by Deteriorating Rhizosphere Environment and Plant Secondary Metabolism in Wheat Seedlings

“…In recent years, scientific attention has been geared toward assessing these negative impacts on crops. , For instance, Varga et al found that exposure to isoproturon (IPU) could inhibit the growth of Lemna minor L. and decrease its amount of proteins and photosynthetic pigments. IPU could also induce oxidative stress in L. minor plants by increasing the levels of hydrogen peroxide (H 2 O 2 ) as well as lipid peroxidation products . Similarly, foliar application of Basagran (35 mg/kg) was found to increase both H 2 O 2 and malondialdehyde (MDA) concentrations in peanut plants, inducing lipid peroxidation and oxidative stress while lowering the levels of chlorophyll a, chlorophyll b and total carotenoids .…”

“…IPU could also induce oxidative stress in L. minor plants by increasing the levels of hydrogen peroxide (H 2 O 2 ) as well as lipid peroxidation products. 9 Similarly, foliar application of Basagran (35 mg/kg) was found to increase both H 2 O 2 and malondialdehyde (MDA) concentrations in peanut plants, inducing lipid peroxidation and oxidative stress while lowering the levels of chlorophyll a, chlorophyll b and total carotenoids. 10 In Ali et al's study, the use of sulfonylurea herbicides displayed toxicity when practicing crop rotation for watermelon cultivation, while exposure to bensulfuron-methyl (10 μg/L) not only decreased root activity but also caused cell death in watermelon, squash, and bottle gourds.…”