Management systems are crucial for soils functioning as a drain or source of greenhouse gas emissions. In this sense, among the alternatives for reducing the precursors of the greenhouse effect are ...integrated agricultural production systems, particularly Agroforestry Systems. These integrated systems maximize the use of biological cycles, soil, and animal waste, reducing agrochemicals and improving the condition of the rural populations involved. The present study aimed to evaluate the CO2 efflux in different land use types. The study was conducted in four agroecosystems: Forest (FO), Agroforestry Systems (AFS), Mandala (MD), and Degraded area (DA). To quantify the CO2 emanating from the soil, 10 mL of 0.5 N KOH aqueous solution is used and titrated using 0.1 N HCl, phenolphthalein, and 1% methyl orange as an indicator. The CO2 concentration from 5:00 am to 5:00 pm was lower. The lowest CO2 production occurred in FO (82.7 CO2 mg m-2 h-1), statistically differing from the other areas that obtained a CO2 rate higher than 140 mg m-2 h-1. As for kinetics, it was observed in all areas that the greatest release of CO2 during the day occurred at 7:00 am, and this release decreased as the soil temperature increased. The greatest release of CO2 and the highest temperatures occurred in DA, showing that these systems with anthropic modifications can be considered CO2 emitters however, systems closer to the natural ecosystem, such as the AFS, will store carbon in the soil, functioning as a carbon store. Therefore, to reduce CO2 emissions from agricultural activities, it is necessary to use systems that imitate natural ecosystems.
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•Dicentrinone was isolated from Ocotea puberula (Lauraceae).•Dicentrinone displayed activity against trypomastigote forms of Trypanosoma cruzi and reduced toxicity (NCTC ...cells)•Dicentrinone causes effects in cellular membrane models represented by DPPE Langmuir monolayers.•Dicentrinone disturbs the cell membrane models altering different physicochemical properties of the lipid surface.
In the present work, the oxoaporphine alkaloid dicentrinone was isolated, for the first time, from leaves of Ocotea puberula (Lauraceae). This alkaloid exhibited antiparasitic activity against trypomastigote forms of Trypanosoma cruzi (IC50 of 16.4 ± 1.7 μM), similar to the positive control benznidazole (IC50 of 18.7 ± 4.1 μM), reduced mammalian cytotoxicity (CC50 > 200 μM), and a selectivity index (SI) higher than 12. These results were correlated with the effects observed using cellular membrane models, represented by 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), in Langmuir monolayers. Dicentrinone was incorporated in the films, submitted to lateral compression, and characterized by tensiometry. As observed in compression-decompression and time-stability curves, dicentrinone expanded the lipid monolayers, decreased the compressional modulus of the film, and reduced the stability of the monolayer. Brewster Angle Microscopy and interfacial Infrared Spectroscopy showed that dicentrinone causes the monolayers to be segregated in phases, and to increase the number of gauche/trans conformers ratio for the lipid acyl methylene groups, indicating configurational disorder. As a result, dicentrinone caused a disturbance in the cell membrane models, altering the physicochemical properties of the lipid surface such as thermodynamic, rheological, morphological, and structural aspects. These results can be useful to understand the interactions between dicentrinone and lipid biological surfaces at the molecular level.
We investigated plankton metabolism and its influence on carbon dioxide (CO2) dynamics in a central Amazon floodplain lake (Janauacá, 3°23′ S, 60°18′ W) from September 2015 to May 2016, including a ...period with exceptional drought. We made diel measurements of CO2 emissions to the atmosphere with floating chambers and depth profiles of temperature and CO2 partial pressure (pCO2) at two sites with differing wind exposure and proximity to vegetated habitats. Dissolved oxygen (DO) concentrations were monitored continuously during day and night in clear and dark chambers with autonomous optical sensors to evaluate plankton metabolism. Overnight community respiration (CR), and gross primary production (GPP) rates were higher in clear chambers and positively correlated with chlorophyll-a (Chl-a). CO2 air-water fluxes varied over 24-h periods with changes in thermal structure and metabolism. Most net daily CO2 fluxes during low water and mid-rising water at the wind exposed site were into the lake as a result of high rates of photosynthesis. All other measurements indicated net daily release to the atmosphere. Average GPP rates (6.8gCm−2d−1) were high compared with other studies in Amazon floodplain lakes. The growth of herbaceous plants on exposed sediment during an exceptional drought led to large carbon inputs when these areas were flooded, enhancing CR, pCO2, and CO2 fluxes. During the period when the submerged herbaceous vegetation decayed phytoplankton abundance increased and photosynthetic uptake of CO2 occurred. While planktonic metabolism was often autotrophic (GPP:CR>1), CO2 out-gassing occurred during most periods investigated indicating other inputs of carbon such as sediments or soils and wetland plants.
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•Large diel variations on CO2 dynamics•Higher plankton metabolism associated with wind mediated mixing.•Phytoplankton consumption of CO2 derived from macrophyte decomposition.•Planktonic respiration is greater in solar exposed chambers.•CO2 emissions enhanced during exceptional drought.
Methane (CH₄) oxidation may consume large amounts of dissolved CH₄ in lakes and wetlands. Here, we estimated CH₄ oxidation rates in an Amazonian floodplain lake during periods representative of the ...annual variations in water level, using incubations and measurements of δ¹³C-CH₄. A large fraction of the CH₄ produced was oxidized (from 34 to ~ 100%, average = 80%), with volumetric CH₄ oxidation rates ranging from 1 to 132 mg C m⁻³ d⁻¹. Heavier values of δ¹³C-CH₄ in surface waters when compared to bottom waters and sediment bubbles corroborates the high CH₄ oxidation rates observed. The depth-integrated oxidation rates were of the same magnitude as the calculate CH₄ evasion to the atmosphere, which indicates that methane oxidation is an important sink of CH₄ and is likely to be important in the many similar lakes encountered in the Amazon River basin.
Cover crops (CCs) have demonstrated their significance in enhancing the agronomic and economic performance of corn in succession. In this paper, we assess the agronomic responses and short-term ...economic returns of adopting cover crops (CCs) for corn cultivation in the sandy soils of the semiarid region of northeast Brazil, with the aim of addressing the additional challenges of CCs adoption in semiarid regions. The field study was conducted in Arapiraca, Alagoas, under no-tillage conditions for two cropping seasons. A randomized complete block design was employed, comprising six CCs (sunn hemp, spectabilis, jack bean, pigeon pea, lab lab, and millet) treatments and one fallow, with 18 replications. The CCs were cultivated for 60 days before corn planting. Drip irrigation was applied during the grain-filling stage of corn growth. Over the two cropping seasons, the biomass and nutrient cycling of the CCs, corn yield, and economic returns were determined, as well as the total organic carbon (TOC) and Mehlich-1 extractable P levels in the soil after corn harvest. The grain yields with sunn hemp, spectabilis, and jack bean were superior (~10%) to that of the fallow (7.7 vs. 7.1 Mg ha−1), irrespective of the cropping season. Sunn hemp exhibited a higher biomass accumulation and ensured greater nutrient cycling, except for K, while lab lab and millet displayed a similar potential, although substantial variations were observed between seasons. Under sunn hemp and jack bean, the TOC increased by ~9%, particularly in the second season. Regarding the available P, spectabilis and jack bean exhibited the highest levels, with an increase of ~74% compared to the fallow (~31.1 vs. 17.9 mg dm−3). Spectabilis and lab lab demonstrated more promising results, both agronomically and economically. However, millet and sunn hemp have the potential to reduce costs over multiple cropping seasons. Therefore, the adoption of cover crops is a sustainable and economically viable agricultural practice. However, it is essential to acknowledge that our results do not represent rainfed conditions and require further investigation.
Soybean (Glycine max L.) is a crop with prominence in Brazil and worldwide. The increase in soybean production and production capacity is associated with scientific and technological advances in the ...productive sector. One of these advances is the use of biostimulants. In this sense, this work aimed to review current knowledge about the effects of biostimulants on soybeans, highlighting the direct or indirect response of the plant when using such substances. This review was carried out through a research with a qualitative approach, being considered a literature review of the narrative type, using other studies and research at the same theme, in high impact magazines from the last five years or more that were relevant to the study, with subsequent critical reading about the subject. Based on found results, it is clear the use of biostimulants in soybeans is a potential alternative input for increasing the growth and development of the crop, as they are able to provide increments in its productive variables. However, further research is needed in order to provide better information on agronomic interests.
Gibberellin is a plant hormone capable of enhancing the productivity of plant’s productivity rants, due to its action in plant physiology, mainly in fruit formation. In this sense, this study aimed ...to evaluate gibberellic acid levels and application times on the growth and quality of ‘Pérola’ pineapple. The experiment was conducted under field conditions in the municipality of Pedras de Fogo, state of Paraíba, Brazil. The treatments consisted of five levels of gibberellic acid (0.0, 1.5, 3.0, 6.0, and 12.0 mg/plant), distributed in a randomized block experimental design, with four repetitions, in which three applications were made at 50, 80, and 110 days after flower induction. The soluble solids content, fruit height, fruit diameter, and weight were evaluated. The period of application and the levels of gibberellic acid altered the responses for the variables analyzed. The level of 7.5 mg/plant of gibberellic acid promoted an increase in the weight and diameter of the fruit. The application at 110 days after floral induction induced an increase in fruit weight and a greater concentration of sugar in the fruit. Further studies on the application of gibberellic acid and periods of application in different soil and climatic conditions should be carried out to determine more consistent results with this crop.
The aim of the present study was to evaluate the accumulation of carbohydrates, protein, and proline as well as the activity of the antioxidant enzymes superoxide dismutase and catalase in the ...Ambiance cultivar of cut rose plants grown with the application of physiological effect products in the Sub-Middle São Francisco River Valley in Brazil. The experiment was performed under a mesh screen with 50% shading. The experimental design used randomized blocks with four repetitions and six treatments: T1) control (water); T2) boscalid; T3) pyraclostrobin; T4) boscalid + pyraclostrobin (T2 + T3); T5) fluxapyroxad + pyraclostrobin; T6) plant growth regulators 4-(indol-3-yl) butyric acid (IBA) + gibberellic acid (GA3) + kinetin; these treatments were applied every 15 days throughout the crop cycle. To determine the accumulation of solutes and enzymatic activity, 8 leaves was collected every 48 h. Leaves were immediately immersed in liquid nitrogen and frozen until further analysis in the laboratory. Results showed that the product combinations boscalid + pyraclostrobin and fluxapyroxad + pyraclostrobin as well as the plant growth regulators were the treatments with the most consistent responses throughout the evaluated cycle, providing a greater accumulation of solutes in rose leaves, as an osmotic adjustment strategy against stress from high temperatures, particularly when proline accumulation is observed. With regard to enzymatic activity, plant regulators showed more consistent results when compared with other treatments, increasing both superoxide dismutase and catalase activity. The marked accumulation of organic solutes and the high enzymatic activity, particularly of catalase, indicated that rose plants use such mechanisms as a defense against the region’s high temperatures.
RESUMO: Objetivou-se, com este estudo, avaliar o acúmulo de carboidratos, proteína e prolina, bem como a atividade de enzimas antioxidantes superóxido dismutase e catalases em plantas de rosa de corte ‘Ambiance’ cultivadas sob aplicação de produtos de efeitos fisiológicos no Vale do Submédio São Francisco. O experimento foi realizado em telado com 50% de sombreamento. O delineamento experimental foi em blocos casualizados com quatro repetições e seis tratamentos: T1) testemunha (água); T2) boscalida; T3) piraclostrobina; T4) boscalida + piraclostrobina (T2 + T3); T5) fluxapiroxade + piraclostrobina; T6) regulador vegetal IBA + GA3 + cinetina, aplicados a cada 15 dias durante todo o ciclo da cultura. Para a determinação do acúmulo de solutos e atividade enzimática foram realizadas 8 coletas de folhas a cada 48 horas. As mesmas foram imediatamente imersas em nitrogênio líquido e congeladas para análise posterior em laboratório. Os resultados demonstram que os produtos conjugados boscalida + piraclostrobina, fluxapiroxade + piraclostrobina e os reguladores vegetais foram aqueles com respostas mais consistentes ao longo do ciclo avaliado, propiciando maior acúmulo de solutos nas folhas das roseiras, como estratégia de ajustamento osmótico diante do estresse por temperatura elevada, especialmente quando se observa o acúmulo de prolina. Para a atividade enzimática, os reguladores vegetais apresentam resultados mais regulares quando comparados aos demais tratamentos, aumentando a atividade da SOD e da CAT. O acúmulo acentuado de solutos orgânicos junto com a elevada atividade enzimática, especialmente da CAT, indicam que as roseiras utilizam tais mecanismos como defesa diante das temperaturas elevadas da região.
Currently, Brazil is the world's largest sugarcane producer, with a planted area of approximately 8.59 million hectares. For being a crop of great prominence in the world economy, sugarcane has been ...widely researched, especially in the study of the causes that limit its productivity, with emphasis on water availability, an important factor to be considered in Brazil, because much of the cultivation takes place in drought regions, and the producing locations are limited to seasonal rainfall. However, sugarcane may present certain mechanisms for tolerance to water stress, especially with the use of foliar fertilization for that tolerance. Therefore, this study aimed to analyze the effects of foliar fertilization as a form of tolerance to water deficit in sugarcane crop. Water stress is the responsible factor for promoting physiological changes in the crop, enabling structural and functional alterations at various organizational levels of the plant. Furthermore, another approach to minimize the effects of water stress in sugarcane is to explore the plant's defense mechanisms, especially with the use of foliar fertilization as an alternative to tolerance to water deficit, considering the several benefits caused by this application method. Plant regulators are a viable option for reducing the negative physiological causes of water stress in plants, besides helping the plant to maintain physiological processes with a rapid recovery after overcoming water stress.
The forage cactus represents one of the main sources of fodder for livestock in the semi-arid region. However, although it is cultivated on a large scale in several regions, there are still few ...studies addressing issues of improved management, especially about irrigation and fertilization of recently used varieties, such as those resistant to false carmine cochineal. Thus, this research aimed to evaluate the effect of different levels of irrigation and sources of organic fertilizer on the productive performance of forage cactus variety Mexican Elephant’s Ear (Opuntia stricta). The experiment was set up at Fazenda Riachão, municipality of Boa Vista, Paraíba. Two types of manure (bovine and caprine) and the control were used, associated with the absence of irrigation and five different depths, which varied from 1.5 to 5.5 L of water per week per plant. A 3x6 factorial design with five repetitions was used in a randomized block design. The depths of water applied promoted a significant increase in the variables analyzed. The goat manure was the most effective in obtaining better values of the number of cladodes per plant and productivity.
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