Canavalia ensiformis enhances the phytoremediation of remineralized and sulfentrazone-contaminated tropical soils

The objective of the study was to assess the phytoremediation potential in two remineralized soils contaminated with sulfentrazone. Two soil types were evaluated: Oxisol (clayey) and Inceptisol (sandy loam), in pots, with and without the incorporation of the rock powder, at rates of 0, 4, and 8 t ha-1. Following this, sulfentrazone was applied at rates of 200, 400, 600, and 800 g a. i. ha-1, in addition to the control treatment without herbicide application, followed by the sowing of Canavalia ensiformis (jack bean). Injury level (IL) was assessed at 42 days after emergence (DAE), and biometric evaluations of the phytoremediating species were conducted at 70 and 120 DAE in the Oxisol and Inceptisol, respectively, for the following variables: height (HT), diameter (DM), trifoliate leaf number (TN), leaf area (LA), above-ground dry biomass (DB), and root dry biomass (RDB). At the end of the phytoremediation experiment, the soils were analyzed using High-Performance Liquid Chromatography (HPLC) and with Sorghum bicolor (sorghum) as a bioindicator to verify the residue of sulfentrazone. IL and DB assessments of the bioindicator species were conducted at 21 DAE. In both soils, higher herbicide rates (600 and 800 g a. i. ha-1) resulted in greater IL and reduced HT, LA, DB, and RDB of the phytoremediating species. C. ensiformis reduced the sulfentrazone residues in the soils. Although it did not directly influence phytoremediation, the rock powder improved soil fertility. In conclusion, C. ensiformis has the potential for effective phytoremediation of soils contaminated with sulfentrazone, providing safety for cultivating sensitive crops and benefiting the environment.

Can herbicides of different mode of action cause injury symptoms in non-herbicide-tolerant young soybean due to simulated drift?

Accidental herbicide drift onto neighboring crops, such as soybeans, can seriously harm non-target plants, affecting their growth and productivity. This study examined the impact of simulated drift from ten different herbicides (2,4-D, dicamba, glyphosate, saflufenacil, oxyfluorfen, hexazinone, diuron, diquat, nicosulfuron, and isoxaflutole) on young soybean plants. These herbicides were applied at three simulated drift levels (1/4, 1/16, and 1/32) equivalent to recommended commercial doses, and the resulting symptoms were carefully evaluated. Simulated drift caused distinctive symptoms, including chlorosis, twisting, necrosis, and growth abnormalities, varying depending on each herbicide's mode of action. Dicamba proved more toxic than 2,4-D, and symptom severity increased with drift proportion, with all herbicides causing over 30% injury at the 1/16 proportion. Notably, 2,4-D, dicamba, glyphosate, hexazinone, and diquat exceeded the half-maximal inhibitory concentration (IC50) value, significantly reducing total biomass. Dicamba consistently caused 50% injury at all proportions, while hexazinone, at the highest dose proportion, led to plant mortality. Dicamba also had biomass accumulation beyond the growth reduction (GR50), whereas hexazinone exhibited less than 10% accumulation due to its capacity to induce plant mortality. This study emphasizes the importance of understanding herbicide drift effects on non-target crops for more effective and safe weed management strategies.

Cow bonechar decreases indaziflam pre-emergence herbicidal activity in tropical soil

The addition of carbonaceous material such as cow bonechar to the soil can affect the availability of applied pre-emergent herbicides such as indaziflam. However, how cow bonechar affects the bioavailability of indaziflam is not yet known. The aim of this study was to evaluate the effect of cow bonechar on herbicidal activity of indaziflam on weeds in a tropical soil. Cow bonechar was added homogeneously to top soil, at 1, 2, 5, 10, and 20 t ha^-1, in addition to treatment with unamended soil. At 21 days after indaziflam (75 g ha^-1) application, injury weed levels, weed species that emerged spontaneously were identified and the weeds present in each sampling unit were collected. Only 1.4 t ha^-1 cow bonechar added to soil was enough to reduce the weed injury level by 50%. From the addition of 2 t ha^-1 cow bonechar the application of indaziflam was not efficient to weed control, being equivalent to treatments without herbicide application. Eight weed species (3 monocots and 5 dicots) were identified in all treatments. Eleusine indica and Digitaria horizontalis accounted for about 99.7% of the entire infestation of the weed community. Cow bonechar decreases indaziflam pre-emergence herbicidal activity in tropical soil for weed control, most likely due to the high sorption and unavailability of the product in the soil solution.