Abstract
The presence or absence of light is one of the most significant environmental factors affecting plant growth and defence. Therefore, the selection of the most appropriate time of application may maximize the benefits of photosynthetic inhibitors. In this work, the concentration and daytime or night-time-dependent effects of bentazon were tested in soybean and common ragweed. The recommended dose (1440 g ha−1) and also half the recommended dose significantly reduced the maximum quantum yield (Fv/Fm) and increased H2O2 levels in common ragweed. Interestingly, bentazon did not change Fv/Fm in soybean. The activity of superoxide dismutase changed in a dose-dependent manner only in common ragweed. The activity of ascorbate peroxidase, catalase and glutathione S-transferase (GST), as well as the contents of ascorbate (AsA) and glutathione (GSH) did not change significantly in this plant species. In soybean, alterations in H2O2 levels were lower but GST and APX activity, as well as AsA and GSH levels were higher compared to common ragweed. At the same time, the rate of lipid peroxidation and ion leakage increased upon bentazon, and were higher in the light phase-treated leaves in the case of both plant species. These results can contribute to optimizing the effects and uses of herbicides in agriculture.
Highlights
Soybean (Glycine max L.) is a very significant crop of the developing world because this plant is an essential source of protein for animal feeds and many packaged meals [1]
The daytime- and night-time-dependent effects of different bentazon concentrations were tested on the photosynthetic activity of both soybean and common ragweed plants based on the measurements of chlorophyll a fluorescence parameters
According to our results it can be concluded that changes in photosynthetic activity, as well as plant defence responses and/or cell death induced by bentazon are dependent on the applied herbicide concentration and plant species and on the time of the application
Summary
Soybean (Glycine max L.) is a very significant crop of the developing world because this plant is an essential source of protein for animal feeds and many packaged meals [1]. The activated antioxidant defence system can substantially and rapidly contribute to cell survival by alleviating the primary and secondary oxidative stress effects of herbicides besides activating other xenobiotic detoxification pathways in plants This was confirmed in both weeds and soybean, where antioxidant enzymes were significantly activated after xenobiotic exposure such as oxyfluorfen [22], linuron [23], dimethenamid [23], glyphosate [24] and paraquat [25]. These results verified the presence of oxidative stress and the significance of antioxidants in defence reactions in the cells of both sensitive and tolerant plants.
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