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Artigo
Corn Cropping System and Nitrogen Fertilizers Technologies Affect Ammonia Volatilization in Brazilian Tropical Soils
(2023-05-27) Santos, César; Pinto, Sheila Isabel do Carmo; Guelfi, Douglas; Rosa, Sara Dantas; Fonseca, Adrianne Braga da; Fernandes, Tales Jesus; Ferreira, Renato Avelar; Satil, Leandro Barbosa; Nunes, Ana Paula Pereira; e Silva, Konrad Passos
The adoption of technologies for N fertilization has become essential for increasing the N use efficiency in no-till (NT) systems in Brazil. Thus, this study aimed to quantify ammonia losses, N removal in grains, and second crop season yield in no-till and conventional (T) areas that received the application of different N fertilizers and their technologies. Ammonia volatilization, N extraction in grains, and corn yield in response to the application of conventional fertilizers were compared to urea treated with urease inhibitors in NT and conventional systems. The treatments were: no-N (Control); Prilled urea (PU); urea + N-(n-Butyl) thiophosphoric triamide (UNBPT); urea + Cu + B (UCuB); ammonium nitrate (AN), and ammonium sulfate (AS). In the NT system, the N-NH3 losses were 49% higher than in the conventional; without differences in corn yield. The fertilizers AN and AS had the lowest N-NH3 losses, regardless of the tillage system. UNBPT reduced the mean N-NH3 loss by 33% compared to PU. UNBPT (1200 mg kg−1 ) and UNBPT (180 mg kg−1 ) reduced the N-NH3 losses by 72% and 22%, respectively, compared to PU in the NT system. We noticed that the NBPT concentration to be used in soils under NT should be adjusted, and a reduction of N-NH3 losses does not directly reflect an increase in yield and N extraction by corn.
Artigo
Control of the fungus Colletotrichum lindemuthianum in common bean plants by 2-methoxy-1,4-naphthoquinone
(2023-08-31) Francisco, Dayane S. M.; Mota, Suellen F.; Carneiro, Paula F.; Ferreira, Vitor F.
The common bean is a crop of high economic importance in countries like Brazil, whose production is affected by the fungus Colletotrichum lindemuthianum, a causal agent of anthracnose. In view of this, twenty six naphthoquinones were synthesized and tested in liquid medium with C. lindemuthianum race 65 (LV134) or race 89 (LV228). After 72 h at 22 °C, under constant stirring, 2-methoxy-1,4-naphthoquinone (11) afforded the lowest value of minimum inhibitory concentration (MIC), which was equal to 15.6 μg/mL, while the commercial fungicide methyl thiophanate had MIC of 61 μg/mL. An aqueous Tween 80® solution of compound 11 was applied to plant leaves of the common bean. Seven days later, an aqueous suspension containing conidia of the race 65 (LV134) fungal strain was sprayed on the leaves. Methyl thiophanate (700 μg/mL) reduced the severity of anthracnose from 5.2 to 1.5, while compound 11 (179 μg/mL) reduced it to 3.5. Then, the most stable conformations of compound 11 were employed in a phamacophoric search in the Ligand Expo database. The amino acid sequences of the proteins complexed to ligands with Tanimoto scores equal to or greater than 0.5 were used in searches of the genomes of fungi. Only those enzymes with scores above 200 for searches carried out exclusively in the genomes of Colletotrichum spp. were selected for docking of compound 11 and inhibitors of the selected enzymes. As the affinities of compound 11 for the enzymes ferulic acid decarboxylase and flavocytochrome b2 were similar to the calculated values for inhibitors of these enzymes, these are probably the targets of compound 11 in C. lindemuthianum. Therefore, both compound 11 and such enzymes have the potential of being used in the development of more efficient chemical structures for the control of this fungus in the common bean.
Artigo
Contributions of climate and Brassica oleracea cultivar to gastropod abundance and assemblage in southeastern Brazil
(2023-04-07) Farias, Elizeu Santos; D'Ávila, Sthefane; Santos, Alerson Araujo; Santos, Rodrigo de Castro; Paes, Jéssica Silva; Guedes, Alexsandro Gomes; Carvalho, Geraldo Andrade; Picanço, Marcelo Coutinho
Terrestrial gastropods (slugs and snails, Mollusca: Eupulmonata) are destructive pests of brassica crops. These organisms defoliate plants and contaminate the harvest, leading to reduced crop yield and marketability. Losses caused by molluscs have escalated in recent years in Brazil. We aimed to determine the seasonal activity of gastropods in brassica fields and unravel the environmental variables associated with these dynamics. Gastropod abundance, assemblage and within-plant distribution were also compared among Brassica oleracea cultivars (broccoli, cabbage and cauliflower). Mild temperatures and rainy periods were found to coincide with gastropod peaks. Regression analyses confirmed a positive association of rainfall and humidity with gastropod abundance, whereas gastropod abundance increased with decreasing temperature. Deroceras laeve (Müller) (Agriolimacidae) and Bradybaena similaris (Férussac) (Bradybaenidae) were the most constant species. Mollusc abundance and assemblage differed amid B. oleracea cultivar; cabbage had the highest abundance and its species composition differed from broccoli and cauliflower. Slugs and snails were more concentrated on lower plant portions, regardless of the cultivar. Management efforts should be reinforced in mild-temperature and rainy periods to reduce damage by gastropods, and cabbage should be monitored more closely than other cultivars.
Artigo
Contribution of (eco)toxicological and risk assessment studies to improve the Brazilian legislation regarding arsenic in the soil environment
(2023-08) Guerra, Marcelo Braga Bueno; Oliveira, Cynthia de; Carvalho, Mariana Rocha de; Silva, Aline Oliveira
Artigo
Copper and silver nanoparticles control coffee rust: decrease the quantity of sprayed active ingredients and is an alternative for sustainable coffee production
(2023-07-16) Leal, Felipe Douglas Soares; Santos Neto, Helon; Pinheiro, Indiara Carol Lopes; Oliveira, Julia Marques; Pozza, Adélia Aziz Alexandre; Pozza, Edson Ampélio
Nanoparticles (NPs) have a high surface/volume ratio and small size (100 ≤ nm, these characteristics allow its use in the management of plant diseases in small quantities. The objective of this study was to evaluate the efficiency of silver (Ag) and copper oxide (CuO) NPs in the control of coffee rust (Hemileia vastatrix Berkeley & Broome). The effect of these NPs at doses of 0, 50, 100, 200 and 400 mg/L on the germination of spores of H. vastatrix and the control of rust in coffee seedlings in a greenhouse was evaluated. The CuO NPs 250 mg/L was also compared with other commercial copper fungicides: copper hydroxide, cuprous oxide and copper chelate (Ethylenediamine tetraacetic acid - EDTA). The incidence and severity of rust were evaluated every seven days, after the appearance the first pustules and the data obtained were transformed into area under disease progress curve for incidence (AUDPCI) and severity (AUDPCS). The 400 mg/L dose of Ag and CuO NPs inhibited 99.8 and 98.4% of H. vastatrix spore germination, respectively. In the greenhouse, in the experiments with Ag and CuO NPs, the lowest AUDPCS was also observed at the dose of 400 mg/L with 97.5 and 92%, respectively. The efficacy of NPs CuO 250 mg/L was equal (p < 0.05) to cuprous oxide, with a reduction of 84.2 and 83.1% of AUDPCS, respectively. Therefore, the potential of Ag and CuO NPs to inhibit the germination of H. vastatrix spores and to control rust in coffee seedlings was verified.