No abstract

The development of harmless substances to replace biocide-based coatings used to prevent or manage marine biofouling and its unwanted consequences is urgent. The formation of biofilms on submerged marine surfaces is one of the first steps in the marine biofouling process, which facilitates the further settlement of macrofoulers. Anti-biofilm properties of a synthetic polyphenolic compound, with previously described anti-settlement activity against macrofoulers, were explored in this work. In solution this new compound was able to prevent biofilm formation and reduce a pre-formed biofilm produced by the marine bacterium, Pseudoalteromonas tunicata. Then, this compound was applied to a marine coating and the formation of P. tunicata biofilms was assessed under hydrodynamic conditions to mimic the marine environment. For this purpose, polyurethane (PU)-based coating formulations containing 1 and 2 wt.% of the compound were prepared based on a prior developed methodology. The most effective formulation in reducing the biofilm cell number, biovolume, and thickness was the PU-based coating containing an aziridine-based crosslinker and 2 wt.% of the compound. To assess the marine ecotoxicity impact of this compound, its potential to disrupt endocrine processes was evaluated through the modulation of two nuclear receptors (NRs), peroxisome proliferator-activated receptor γ (PPARγ), and pregnane X receptor (PXR). Transcriptional activation of the selected NRs upon exposure to the polyphenolic compound (10 µM) was not observed, thus highlighting the eco-friendliness towards the addressed NRs of this new dual-acting anti-macro- and anti-microfouling agent towards the addressed NRs.

Capim-amargoso e milho voluntário destacam-se como as principais espécies invasoras no cultivo da soja ocasionando perdas de produtividade devido a matocompetição. Este trabalho teve como objetivo estudar herbicidas pré-emergentes para o controle do capim-amargoso (Digitaria insularis) e do milho voluntário. Para tanto, foi realizado experimento em casa de vegetação, no delineamento experimental inteiramente casualizado, com seis tratamentos e quatro repetições, sendo os tratamentos: S-metolachlor (1152 g ha-1), diclosulam (25,2 g ha-1), imazethapyr (80 g ha-1), flumioxazin (60 g ha-1), [imazethapyr + flumioxazin] [106 + 50 g ha-1] e testemunha sem herbicida. As aplicações foram realizadas imediatamente após a semeadura das espécies, procedendo o umedecimento do solo contido nos vasos. Foi avaliado a porcentagem de controle aos 14, 21 e 28 dias após a emergência (DAE), número de plantas emergidas e massa seca das plantas aos 28 DAE. Os herbicidas que proporcionaram maiores níveis de controle sobre plantas de capim-amargoso quando aplicados em pré-emergência foram S-metolachlor (1152 g ha-1) e flumioxazin (60 g ha-1). Para o controle do milho voluntário [imazethapyr + flumioxazin] [106 + 50 g ha-1] e diclosulam (25,2 g ha-1) consistiram como as melhores alternativas. Para o controle das duas espécies simultaneamente, [imazethapyr + flumioxazin] mostrou-se eficiente, tal como, a possibilidade da associação entre os herbicidas (S-metolachlor + diclosulam) e (flumioxazin + diclosulam).

ABSTRACT The spatial arrangement of plants in the cultivation area is a factor that directly influences grain yield, since the best arrangement can result in the greater use of water, light and nutrients. The aim of the study was to evaluate the agronomic performance of sorghum sown in double row spacing in the Brazilian Cerrado. For this purpose, field experiments were conducted in the 2018 and 2019 seasons in a complete block design with a factorial scheme of 2 x 5. There were four replications, using two row spacing: traditional (0.50 m) and double rows (0.25 m/0.75 m) and five plant populations: 120, 180 (recommended), 240, 300 and 360 thousand, plants ha-1. Morphological characteristics, yield components and grain yield were evaluated using joint data analysis for the two years of study. In 2018, due to lower rainfall during the crop season, the use of a double row arrangement presented grain yield lower than traditional spacing. On the other hand, in 2019, the year with the best water distribution, the yield was superior to that of 2018. The increase in plant population per hectare increased the yield of sorghum grains, with gains of up to 24% in relation to the recommended population of 180 thousand plants ha-1, demonstrated that the densification in this crop can be a promising technique as long as its cost/benefit is considered.

Hazard assessment strategies are often supported by extrapolation of damage probabilities, regarding chemical action and species susceptibilities. Yet, growing evidence suggests that an adequate sampling of physiological responses across a representative taxonomic scope is of paramount importance. This is particularly relevant for Nuclear Receptors (NR), a family of transcription factors, often triggered by ligands and thus, commonly exploited by environmental chemicals. Within NRs, the ligand-induced Ecdysone Receptor (EcR) provides a remarkable example. Long regarded as arthropod specific, this receptor has been extensively targeted by pesticides, seemingly innocuous to non-target organisms. Yet, current evidence clearly suggests a wider presence of EcR orthologues across metazoan lineages, with unknown physiological consequences. Here, we address the state-of-the-art regarding the phylogenetic distribution and functional characterization of metazoan EcRs and provide a critical analysis of the potential disruption of such EcRs by environmental chemical exposure. Using EcR as a case study, hazard assessment strategies are also discussed in view of the development of a novel “precision hazard assessment paradigm.

No abstract

The advance of intercropping has generated the need for studies that evaluate methods of suppression of forage grasses in order to not harm the development of the commercial culture. The aim of this study is to evaluate the sensitivity of forage grasses to post-emergence herbicide application. To this end, an experiment was carried out in a greenhouse using a randomized complete block design in a 4 x 9 factorial scheme with four replicates. The first factor consisted of the forage grasses Urochloa ruziziensis, Panicum maximum cv. BRS Tamani, P. maximum cv. BRS Quênia, and P. maximum cv. BRS Zuri. The second factor consisted of the combination of eight herbicide treatments applied at post-emergence in association with atrazine (1200 g a.i. ha -1 ), besides a control treatment, without application. P. maximum cv. BRS Quênia was the least sensitive to post-emergence herbicide application. Tembotrione (42 and 84 g a.i. ha -1 ) and mesotrione (48 and 96 g a.i. ha -1 ) have potential for suppression of U. ruziziensis. Tembotrione (84 g a.i. ha -1 ), glyphosate (200 g a.i. ha -1 ), and nicosulfuron (7.8 g a.i. ha -1 ) have potential for suppression of the cv. BRS Quênia, and tembotrione (42 g a.i. ha -1 ) and mesotrione (96 g a.i. ha -1 ) have potential for the suppression of BRS Tamani. The P. maximum cv. BRS Zuri presented a higher plant height, shoot dry matter, and root dry matter than the other forages evaluated. For this forage, the use of nicosulfuron herbicides at post-emergence, regardless of the dose, reduced the shoot dry matter by 70%.

Soybean-maize succession is the main annual cropping system used in Brazilian cerrado. However, due to water restrictions, the cultivation of maize (off-season crop) is not viable after cultivation of late maturing soybean cultivars and/or when late soybean seeding occurs due adverse weather conditions. In this scenario, the use of cover crops can be a good option to benefit soil health and consequently the soybean yield in the next crop season. The objective is to evaluate the effects of cover crops on biomass inputs, nutrient cycling, and nematode control during the off-season in the Cerrado biome. The study was conducted for three years in two locations in the state of Goiás. We evaluated five options of cover crops after soybean cultivation: 1) Mix of cover crops (Pennisetum glaucum, Crotalaria spectabilis, and Urochloa ruziziensis), 2) P. glaucum, 3) C. spectabilis, 4) U. ruziziensis 5) U. brizantha cv. Marandu, and 6) U. brizantha BRS Paiaguás. The results revealed that Pennisetum glaucum (9633 and 6958 kg ha-1 in Montividiu and Rio Verde) and U. brizantha cv. Marandu (8015 kg ha-1 in Rio Verde) produced the highest amount of biomass on average over three years. The treatments soybean/Crotalaria spectabilis and soybean/Pennisetum glaucum reduce the population of the nematodes. However, the use of a more diversified system such as the mix of cover crops provided a greater soybean yield, soil coverage and a high concentration and release of nutrients during the soybean cycle. Being one important alternative for ensure agricultural sustainability in the Cerrado.