Incised valley paleoenvironments interpreted by seismic stratigraphic approach in Patos Lagoon, Southern Brazil

<div><p>ABSTRACT: The Rio Grande do Sul (RS) coastal plain area (33,000 km 2 ) had its physiography modified several times through the Quaternary, responding to allogenic and autogenic forcings. The Patos Lagoon covers a significant area of RS coastal plain (10,000 km 2 ), where incised valleys were identified in previous works. About 1,000 km of high resolution (3.5 kHz) seismic profiles, radiocarbon datings, Standard Penetration Test (SPT) and gravity cores were analyzed to interpret the paleoenvironmental evolution as preserved in incised valley infills. Seismic facies were recognized by seismic parameters. The sediment cores were used to ground-truth the seismic interpretations and help in the paleoenvironmental identification. Key surfaces were established to detail the stratigraphical framework, and seismic facies were grouped into four seismic units, which one classified in respective system tracts within three depositional sequences. The oldest preserved deposits are predominantly fluvial and estuarine facies, representing the falling stage and lowstand system tracts. The Holocene transgressive records are dominated by muddy material, mainly represented by estuarine facies with local variations. The transgression culminated in Late Holocene deposits of Patos Lagoon, representing the highstand system tract. The depositional pattern of the vertical succession was controlled by eustatic variations, while the autogenic forcing (paleogeography and sediment supply) modulated the local facies variation.</p></div

Estudos sobre a nutrição mineral do arroz: XI. Marcha de absorção de micronutrientes pela variedade IAC-47

Dry matter yield and uptake of B, Cu, Fe, Mn and Zn by the rice variety IAC-47 were studied under controlled conditions, namely, by growing plants in nutrient solution and by falcing samples for analyses in set physiological periods. It was observed that only the curves describing dry matter production and accumulation of B and Fe was verified.A produção de matéria seca e a absorção de micronutrientes (B, Cu, Fe, Mn e Zn) pelo arroz var. IAC-47 foram estudadas usando-se plantas cultivadas em solução nutritiva. Verificou-se que: enquanto as curvas que descrevem o crescimento e a acumulação de B e Fe mostram tendência sigmóide, as demais não o fazem, evidência de redistribuição foi observada somente nos casos do B (diminuição no conteúdo foliar) e no do Fe (diminuição no conteúdo da raiz)

Estudos sobre a nutrição mineral do arroz: XIII. efeitos das deficiências de micronutrientes nas variedades IAC-25 e IAC-47

Rice plants were grown in nutrient solution lither in the presence or in the absence of B, Cu and Zn. The symptoms of deficiency were usually in agreement with those described in the literature. Growth of the variety IAC-47 (number of leaves, tillering and total dry matter) was relatively more affected; this variety, however did produce grains under the minus Cu treatment (one fourth of the yield observed in the "complete" treatment), which did not happen in the case of the other variety. At the beginning of the grain filling period the following leaf contents could be considered as indication of deficiency: B-13 to 25 ppm; Zn-20 ppm; no conclusion could be drawn with respect to Cu levels.Plantas de arroz, variedades IAC-25 e IAC-47 foram cultivadas em solução nutritiva e com deficiência de B, Cu e Zn. Foram obtidos sintomas de carência dos três micronutrientes. As deficiências induzidas provocaram diminuição na matéria seca total e no número de folhas das duas variedades. O mesmo ocorreu no numero de perfilhos da var. IAC-47. Foi feita a determinação dos teores dos micronutrientes nas plantas submetidas aos diferentes tratamentos o que forneceu dados que ajudam a avaliação do estado nutricional