Universidade Federal de Santa Maria

About: Universidade Federal de Santa Maria is a education organization based out in Santa Maria, Brazil. It is known for research contribution in the topics: Population & Context (language use). The organization has 21178 authors who have published 35632 publications receiving 371665 citations.

Atributos físicos e rendimento de grãos de trigo, soja e milho em dois Latossolos compactados e escarificados

Abstract: Soil compaction affects structural quality in areas under no-tillage systems and reduce crop yield, particularly in clayey soils. The objective of this study was to evaluate the impact of three compaction states on crop yield and soil physical attributes in two Oxisols under no-tillage and chiseling. The soil bulk density (Ds), soil resistance to penetration (Rp) and crop yield of the wheat, soybean and corn were determined. One Oxisol (LVd) has 550g kg -1 of clay and other (LVdf) 610g kg -1 clay, located in Rio Grande do Sul plateau. The experiment was run from 1999 to 2001 in a commercial crop field mapped with respect to soil resistance to penetration. Three states of compaction were separated and mapped: a) EC1- higher compaction state located at the head of crop site; b) EC2medium state of compaction and; c) EC3 lower state of compaction toward central part of the site. To serve as no compacted area a plot was chiselled. The highest values of Ds (1.62 e 1.54Mg m -3 ) and Rp (3.4 e 3.8MPa), respectively for LVd and LVdf, cultivated under no-tillage system, were found in the layer of 0.07-0.12m. The systematic mobilization by chiseling mechanisms of the planters reduced Ds in 26% on LVd e 15% on LVdf, compaction in the layer of 0.00-0.05m in relation the depth of 0.07-0.12m. The highest soil compaction state (EC1) in relation the lower state of compaction (EC3) in the two Oxisols decreased crop yield of wheat in 18% and 34%, respectively for LVd e LVdf and corn in 24% on LVdf, but not of soybean. The soil chiseling increased corn and wheat grain yield in relation to the three states of soil compaction.

Conservation tillage for cassava (Manihot esculenta crantz) production in the tropics

Abstract: Cassava (Manihot esculenta crantz) is often cultivated on tilled plots, traditionally on mounds and ridges with the use of hand hoes or tractor driven implements. These two conditions alter the soil structural parameters and most times increase the vulnerability of soil to erosion or compaction as a result of frequent machine movement under the conventional tillage system. A review of the effects of tillage systems on soil bulk density, total porosity and penetration resistance was conducted to investigate the effectiveness of soil conservation for the optimum production of cassava in the tropics. Tillage treatments under review were: conventional tillage (CT), no-till (NT), minimum tillage (MT) and soil compaction (CP). Our review indicated that the bulk density (BD) in plots under CT was not significantly different (p < 0.05) from the value of BD in plots under minimum tillage (MT) within the 0–5 cm soil layer, but was highest in soils under compaction due to traffic passes of heavy duty equipment. Soils under no-till were characterized with lowest bulk density within the 0–5 cm layer, but gradually increased in BD within the 10–20 cm soil layer, which offers the soil some structural stability. However, the difference in bulk densities between plots under NT and CP treatments were highly significant at p < 0.05, with CP plots having the highest bulk density within the 0–30 cm soil layer. Total porosity was highest in soils under conventional tillage (CT) comparatively with other tillage systems. Organic matter accumulation in NT treatment resulted to higher total porosity compared with other systems except CT at the surface soil (0–5 cm) but with reduced porosity at the sub-surface soil. Total porosity was least in plots under traffic passes (compacted plots). Statistically, there were no significant differences in total porosity among plots under conventional tillage with mulch residues, conventional tillage without mulch residues and minimum tillage with mouldboard at the p < 0.05. However, plots under minimum tillage without mouldboard had lower total porosity. Penetration resistance was higher in NT plots when compared with plots under CT system, except from compacted plots (CP), which offered highest resistance to penetration. A long term experiment showed that cassava root yield was highest under NT with mulch residues, with or without fertilizer application. The reviewed work further confirmed that cassava can be grown successfully under no-till (NT) to give the optimum growth and yield required of the crop, while conserving the soil physical properties.

Mechanisms of cisplatin ototoxicity: theoretical review

Abstract: Introduction:Cisplatin is an effective chemotherapeutic agent commonly used in the treatment of malignant tumours, but ototoxicity is a significant side effect.Objectives:To discuss the mechanisms of cisplatin ototoxicity and subsequent cell death, and to present the results of experimental studies.Material and methods:We conducted a systematic search for data published in national and international journals and books, using the Medline, SciELO, Bireme, LILACS and PubMed databases.Results:The nicotinamide adenine dinucleotide phosphate oxidase 3 isoform (also termed NOX3) seems to be the main source of reactive oxygen species in the cochlea. These reactive oxygen species react with other molecules and trigger processes such as lipid peroxidation of the plasma membrane and increases in expression of the transient vanilloid receptor potential 1 ion channel.Conclusion:Cisplatin ototoxicity proceeds via the formation of reactive oxygen species in cochlear tissue, with apoptotic cell death as a consequence.