Evaluación de gramíneas y leguminosas forrajeras como coberturas y su influencia en el control de malezas en el establecimiento de cítricos en el piedemonte del Meta.

In order to develop sustainable management systems for growing citrus in the tropics, the behavior of two species of legumes and four grasses were evaluated and compared with mechanical and chemical control in high terrace conditions of the Meta piedmont. The trial was established Desmodium ovalifolium cv. Maquenque, Paspalum notatum, Brachiaria dictyoneura cv. Llanero, Arachis pintoi CIAT 18744, Brachiaria brizantha cv. Toledo, Panicum maximum CIAT 36000, and the controls herbicide, brushcutter + herbicide. Experimental located on the streets of the Valencia orange orchard in Corpoica’s La Libertad research center in Villavicencio. The following variables were evaluated: the percentage of coverage and biomass production for two years, and resistance to penetration (RP) at the end of the experiment. To analyze the results, descriptive statistics, analysis of variance, and comparison using the least significant difference (LSD) were applied. The highest percentages of land cover on average were A. pintoi, P. maximum, and B. dictyoneura, with 96.98%, 95.98% and 94.5% land cover, respectively. In the 753 days after the test began, we found that P. maximum had produced 20,053 kg ha-1 of dry matter, followed by B. brizantha with 13,624 kg ha-1, which exceeded all other treatments statistically. However, A. pintoi was the species that generated the least RP, followed by D. ovalifolium. The results obtained show advantages in the use of coverage in the establishment phase of citrus such as weed control, reduced resistance to penetration, and the protection of soil from erosion by runoff.  Con el propósito de desarrollar sistemas de manejo sostenible para el cultivo de cítricos en el trópico bajo, se evaluó el comportamiento de dos especies de leguminosas y cuatro gramíneas en comparación con el control mecánico y químico, en condiciones de terraza alta del Piedemonte del meta. se establecieron las especies Desmodium ovalifolium cv. Maquenque, Paspalum notatum, Brachiaria dictyoneura cv. Llanero, Arachis pintoi CIAT 18744, Brachiaria brizantha cv. Toledo y Panicum maximum CIAT 36000, y los controles herbicida, guadaña + herbicida. El área experimental se estableció en las calles de un cultivo de naranja Valencia del Centro Investigación La Libertad de Corpoica en Villavicencio. Se evaluaron las variables porcentaje de cobertura y producción de biomasa durante dos años, y resistencia a la penetración (RP) al finalizar el experimento. Para el análisis de los resultados se utilizó estadística descriptiva, análisis de varianza y comparación de medias con la diferencia mínima significativa (DMS). Los mayores porcentajes de cobertura del suelo se obtuvieron con A. pintoi, P. maximun y B. dictyoneura, con 96,98%; 95,98% y 94,5%, respectivamente. En los 753 días después de establecido el ensayo, se encontró que P. maximum, produjo 20.053 kg ha-1 de materia seca, seguido de B. brizantha con 13.624 kg ha-1, los cuales superaron estadísticamente a otros tratamientos. Por otro lado, A. pintoi fue la especie que generó la menor RP seguida de D. ovalifolium. Los resultados obtenidos señalan ventajas en el uso de coberturas en la fase de establecimiento del cultivo de cítricos en cuanto al control de malezas, disminución de la resistencia a la penetración y protección del suelo a la erosión por escorrentía.

Impact of amendments on the physical properties of soil under tropical long-term no till conditions

Tropical regions have been considered the world's primary agricultural frontier; however, some physico-chemical deficiencies, such as low soil organic matter content, poor soil structure, high erodibility, soil acidity, and aluminum toxicity, have affected their productive capacity. Lime and gypsum are commonly used to improve soil chemical fertility, but no information exists about the long-term effects of these products on the physical attributes and C protection mechanisms of highly weathered Oxisols. A field trial was conducted in a sandy clay loam (kaolinitic, thermic Typic Haplorthox) under a no-tillage system for 12 years. The trial consisted of four treatments: a control with no soil amendment application, the application of 2.1 Mg ha-1 phosphogypsum, the application of 2.0 Mg ha-1 lime, and the application of lime + phosphogypsum (2.0 + 2.1 Mg ha-1, respectively). Since the experiment was established in 2002, the rates have been applied three times (2002, 2004, and 2010). Surface liming effectively increased water-stable aggregates > 2.0 mm at a depth of up to 0.2 m; however, the association with phosphogypsum was considered a good strategy to improve the macroaggregate stability in subsoil layers (0.20 to 0.40 m). Consequently, both soil amendments applied together increased the mean weight diameter (MWD) and geometric mean diameter (GMD) in all soil layers, with increases of up to 118 and 89%, respectively, according to the soil layer. The formation and stabilization of larger aggregates contributed to a higher accumulation of total organic carbon (TOC) on these structures. In addition to TOC, the MWD and aggregate stability index were positively correlated with Ca2+ and Mg2+ levels and base saturation. Consequently, the increase observed in the aggregate size class resulted in a better organization of soil particles, increasing the macroporosity and reducing the soil bulk density and penetration resistance. Therefore, adequate soil chemical management plays a fundamental role in improving the soil's physical attributes in tropical areas under conservative management and highly affected by compaction caused by intensive farming

A Bone Remodelling Model Based on Generalised Thermodynamic Potentials and Optimisation Applied to a Trabecula with Cyclic Loading

Background: Bone diseases caused by an imbalance of bone turnover represent a major public health concern worldwide. Studies involving bone remodelling mechanisms can assist in the treatment of osteoporosis, osteopenia and in cases of fractures. In recent decades several authors have developed bone remodelling models

1H NMR chemical profile and antioxidant activity of Eugenia punicifolia extracts over seasons: a metabolomic pilot study.

Eugenia punicifolia (Kunth) DC. is a medicinal plant used to treat diseases related to oxidative processes. In this work, H-1 nuclear magnetic resonance (NMR) spectroscopy and multivariate analysis have been employed to track the chemical changes and antioxidant activity of dimethyl sulfoxide (DMSO) extracts from E. punicifolia leaves over seasons. Principal component analysis (PCA) applied to H-1 NMR allowed discriminating DMSO extracts from leaves collected in the dry and rainy seasons and pointed out sucrose, catechin, and epicatechin as responsible for separating dry season samples and quercetin, acid gallic, glucose, and fatty acids contributed for rainy samples grouping. Notably, antioxidant assays revealed that dry season extracts exhibited a higher radical scavenging capacity. When those compounds were submitted to partial least squares-discriminant analysis (PLS-DA) only sucrose and fatty acids presented variable importance projection (VIP) score > 1, both metabolites are related somehow to the defense mechanisms of the plant. This pilot study may suggest new experimental approaches for more effectively monitoring the spectrum-effect relationship of E. punicifolia leaf extracts

Produtividade da mandioca (manihot esculenta crantz) em três sistemas de preparo do solo.

A cultura da mandioca predispõe as áreas de cultivo a grandes perdas de solo e de água decorrentes do processo erosivo, em função de seu crescimento inicial lento, do espaçamento relativamente largo, e da grande movimentação do solo, que normalmente ocorre por ocasião da colheita. Nas regiões Noroeste e Centro-Oeste do Estado do Paraná, a cultura da mandioca ocupa 48% da área total cultivada, ou seja 65.000 ha (Groxko, 2003). Estas regiões são constituídas, em sua maioria, por solos de textura média a arenosa, que são muito susceptíveis à erosão. Nestas áreas, o cultivo intensivo tem propiciado uma redução gradativa da produtividade das culturas devido a uma perda gradativa da qualidade do solo, resultante do processo de erosão (Fidalski, 1997). Uma alternativa para evitar estas perdas de solo por erosão é a adoção de práticas de preparo que resultem em uma mínima movimentação de solo. Entretanto, são poucos os trabalhos relacionados aos efeitos de sistemas de preparo de solo na produtividade da mandioca no Brasil, especialmente na região Noroeste do Estado do Paraná. Assim sendo, o objetivo deste trabalho foi avaliar o efeito de sistemas de preparo de solo na produtividade da cultura da mandioca, submetida a três sistemas de preparo de solo, ao longo de quatro cultivos sucessivos

Green Synthesis of Spiro Compounds with Potential Anticancer Activity through Knoevenagel/Michael/Cyclization Multicomponent Domino Reactions Organocatalyzed by Ionic Liquid and Microwave-Assisted

In this work a microwave-assisted Knoevenagel/Michael/cyclization multicomponent domino methodology, using ethanol as solvent and the ionic liquid 1-methylimidazolium chloride as catalyst was developed for the synthesis of spiro compounds. The reaction conditions considered ideal were determined from a methodological study varying solvent, catalyst, amount of catalyst, temperature, and heating mode. Finally, the generality of the methodology was evaluated by exploring the scope of the reaction, varying the starting materials (isatin, malononitrile, and barbituric acid). Overall, the twelve spiro compounds were synthesized in good yields (43–98%) and the X-ray structure of compound 1b was obtained. In addition, the in vitro antiproliferative activities of the spirocycles against four types of human cancer cell lines including HCT116 (human colon carcinoma), PC3 (prostate carcinoma), HL60 (promyelocytic leukemia), and SNB19 (astrocytoma) were screened by MTT-based assay. It is noteworthy that spiro compound 1c inhibited the four cell lines tested with the lowest IC50 values: 52.81 μM for HCT116, 74.40 μM for PC3, 101 μM for SNB19, and 49.72 μM for HL60

POTASSIUM FERTILIZATION AND SOIL MANAGEMENT SYSTEMS FOR COTTON CROPS

Cotton has great socio-economic importance due to its use in textile industry, edible oil and biodiesel production and animal feed. Thus, the objective of this work was to identify the best potassium rate and soil management for cotton crops and select among cultivars, the one that better develops in the climatic conditions of the Cerrado biome in the State of Goiás, Brazil. Thus, the effect of five potassium rates (100, 150, 200, 250 and 300 kg ha-1 of K2O) and two soil management systems (no-till and conventional tillage) on the growth, development and reproduction of four cotton cultivars (BRS-371, BRS-372, BRS-286 and BRS-201) was evaluated. The data on cotton growth and development were subjected to analysis of variance; the data on potassium rates were subjected to regression analysis; and the data on cultivars and soil management to mean test. The correlation between the vegetative and reproductive variables was also assessed. The conventional tillage system provides the best results for the herbaceous cotton, regardless of the others factors evaluated. The cultivar BRS-286 has the best results in the conditions evaluated. The cultivar BRS-371 under no-till system present the highest number of fruiting branches at a potassium rate of 105.5% and highest number of floral buds at a potassium rate of 96.16%. The specific leaf area was positively correlated with the number of bolls per plant at 120 days after emergence of the herbaceous cotton