RESUMO O Estado do Rio Grande do Sul é o maior produtor de arroz irrigado do País, com destaque para a região da Fronteira Oeste. O objetivo deste trabalho foi avaliar propriedades físicas do solo e a produtividade de arroz irrigado por inundação em plantio direto e convencional, em níveis de palha residual de arroz em plantio direto. O delineamento experimental foi inteiramente casualizado, com quatro experimentos e 10 repetições nos experimentos 1, 2 e 3 e seis no experimento 4. Os sistemas de manejo foram: experimento 1 (E1), sistema PD (E1PD) e sistema convencional com duas gradagens na camada de 0-7 cm + remaplan (E1C), em área de um ano de cultivo de arroz, após sete anos de pousio do cultivo de arroz e semeadura de azevém no inverno, com pastejo animal o ano todo; experimento 2 (E2), sistema PD (E2PD) e sistema convencional (E2C), após campo nativo; experimento 3 (E3), sistema PD (E3PD) e sistema convencional (E3C), após plantio direto de arroz irrigado durante dois anos em área de campo nativo; e no experimento 4 utilizaram-se quatro níveis de palha residual antes da semeadura do arroz. A produtividade de arroz irrigado por inundação não diferiu entre os sistemas plantio direto e convencional. A massa seca residual do arroz antes da semeadura não influenciou a produtividade de arroz irrigado por inundação.Termos de indexação: restos culturais, plantio direto, rendimento, Oryza sativa.
RESUMOO objetivo deste trabalho foi identificar, por meio de análise de imagens de raios X, se existem diferenças morfológicas em sementes de arroz produzidas em diferentes regimes hídricos e verificar a relação entre a morfologia das sementes e a germinação. Sementes de arroz dos cultivares IRGA 417, IRGA 424 e INOV CL foram produzidas no município de Itaqui, Estado do Rio Grande do Sul, sob diferentes regimes hídricos, em dois sistemas de irrigação: inundado e aspersão. Os tratamentos utilizados constituíram-se em sistema de irrigação por aspersão, com quatro lâminas de irrigação (50%, 100%, 150% e 200% de evapotranspiração da cultura) e sistema de irrigação por inundação. A colheita das sementes foi realizada de forma manual quando as mesmas apresentavam em média 23% de grau de umidade base seca, procedendo-se a secagem até atingirem em média 13% e posteriormente foram armazenadas em sacos de papel em ambiente de laboratório sem controle das condições ambientais. Após 12 meses de armazenamento, as sementes foram submetidas ao teste de raios X, para obtenção das imagens e em seguida foram conduzidas ao teste de germinação, com contagem de plântulas normais 5 dias após a semeadura. A análise de imagens de raios X permite a identificação de alterações e danos internos em sementes de arroz produzidas em diferentes regimes hídricos, com reflexos negativos no potencial fisiológico das sementes produzidas sob regime de menor disponibilidade hídrica. Palavras ABSTRACTThe objective of this study was to identify by X-ray image analysis, the existence of morphological differences in rice seeds produced under different water regimes, and to determine the relationship between seed morphology and seed germination. Rice seeds of
ResumoO objetivo deste trabalho foi avaliar o efeito de sistemas de manejo e da palha residual na produtividade de arroz irrigado por inundação. O delineamento experimental foi inteiramente casualizado, com três experimentos e, dez repetições nos experimentos 1 e 2 e, 6 repetições no experimento 3. Os experimentos foram: E1 -sistema plantio direto (E1PD) e sistema convencional com duas gradagens na camada de 0,0 -0,07 m + aplainamento com remaplam (E1PC), em área de três anos de cultivo de arroz, após pousio do cultivo de arroz e semeadura de azevém no inverno, com pastejo animal o ano todo; E2 -sistema plantio direto (E2PD) e sistema convencional (E2PC), após campo nativo; E3 -plantio direto com ausência de palha na superfície do solo (E30P), palha atual na superfície do solo de 3.726 kg ha -1 (E31P), duas vezes a quantidade de palha atual, 7.452 kg ha -1 (E32P) e três vezes a quantidade de palha atual, 11.178 kg ha -1 (E33P). No solo, foram avaliados o diâmetro médio geométrico dos agregados, a densidade, porosidade total, macro e microporosidade, nas camadas de 0,0 -0,05 e 0,05 -0,10 m. Na colheita, foram avaliados o número de panículas em área de 0,25 m 2 , número de grãos cheios, vazios e total em 10 panículas, massa de mil sementes e a produtividade de grãos de arroz em 2 m 2 . O sistema de manejo convencional apresenta maior macroporosidade e porosidade total do solo, comparado ao sistema plantio direto, porém, não resulta em diferença nos componentes de produção e produtividade de grãos de arroz. O manejo do solo em sistema plantio direto, com a quantidade de palha de arroz na superfície do solo de até 11.178 kg ha -1 , antes da semeadura, não reduz a produtividade de grãos de arroz irrigado por inundação. Palavras-chave: Sistema convencional, plantio direto, restos culturais, rendimento, Oryza sativa AbstractThe objective of this study was evaluate the effect of management systems and straw in flooded irrigated rice yield. The experimental design was a completely randomized with three experiments and, 10 replications in experiment 1 and 2 and, 6 replications in experiment 3. The experiments were: E1 -no-till system (E1PD) and conventional system with two harrowings at 0.0-0.07 m layer and leveling with remaplam (E1PC), after three years of sowing rice, after fallow of rice tillage, with sowing of rye grass in winter and grazing; E2 -no-till system (E2PD) and conventional system after native field
ABSTRACT:A compacted subsurface soil layer can be a limiting factor for soybean growing, reducing soybean yield. The aim of this study was to evaluate the effect of different tillage systems on the physical properties of two Albaqualf soils of the Central Plains region in the state of Rio Grande do Sul in southern Brazil. Two experiments were conducted: one in Santa Maria, RS, during the 2013/14 and 2014/15 crop seasons, and another in Formigueiro, RS, during the 2013/14 crop season. A randomized block experimental design with four replications was used. The treatments were: sowing using an offset double disc (T1); sowing using a fluted coulter disc (wavy disc with 12 waves) (T2); sowing with a knife runner opener (T3); sowing with a knife runner opener + press wheel mechanism for ground levelling (T4); sowing using a furrow opener upon a raised bed (T5); and chisel plough + sowing using an offset double-disc (T6). In the 2014/15 growing season, the T4 factor was changed using a knife runner opener 0.05 m from the planting row. A smaller reduction in the compacted subsurface soil layer was observed for both T1 and T2, which exhibited high soil bulk density values for the 2013/14 and 2014/15 crop seasons. Furthermore, T3, T5 and T6 led to a reduction in bulk density, and increasing total porosity and macroporosity in the soil, which consequently increased water infiltration, water storage capacity, and crop yield in areas with the presence of a compacted subsurface soil layer.
Rice monoculture in lowlands can cause problems for management practices in crop fields, for example, in weed control. For this reason, corn in rotation with irrigated rice in lowlands may be advantageous, despite problems with soil compaction and water excess. The objective of this study was to evaluate soil physical properties and corn performance in soil management systems in an Albaqualf soil (lowlands). Two experiments were conducted in the field, in the 2013/14 and 2014/15 crop seasons. The experimental design was randomized blocks with two factors. There were three levels for the first factor, consisting of soil management practices: soil chiseling 45 days before sowing to a depth of 0.3 m; conventional tillage with two diskings to a depth of 0.1 m and subsequent leveling of the soil; and no-till. The second factor was composed of two levels: sowing on raised seedbeds, and without raised seedbeds. The soil parameters of bulk density, total porosity, macroporosity, microporosity, volumetric moisture, and soil resistance to mechanical penetration (RP) were evaluated. The corn parameters were plant height, shoot dry matter, leaf area, height of the first ear of corn, grains per ear, and grain yield. Soil chiseling resulted in lower RP and higher macroporosity in the 0.1-0.2 and 0.2-0.3 m layers. In raised seedbeds, the 0.00-0.05, 0.05-0.10, and 0.10-0.20 m layers were lower in RP and bulk density. Moreover, higher soil macroporosity was observed in relation to the treatment without raised seedbeds. In general, the highest grain yields were found in the treatments with lower RP and higher macroporosity in the root system region. Increased porosity accelerated water drainage in the soil, reducing the time that soil airspace was filled with water, which is a limiting factor for root development. In Albaqualf soils, planting corn in chiseled soil provides higher corn yields compared to conventional tillage, and planting corn on raised seedbeds provides higher corn yields compared to the lack of raised seedbeds.
Resumo -O objetivo deste trabalho foi avaliar a escarificação mecanizada do solo e diferentes sulcadores, em semeadora, para cultivo de milho em Planossolos. Dois experimentos foram realizados em campo, em dois locais: Santa Maria e Formigueiro, RS. Um delineamento experimental de blocos ao acaso foi utilizado, com quatro repetições e tratamentos de escarificação do solo (ESC) e semeadura direta, com os seguintes sulcadores: haste sulcadora (HS), haste sulcadora e mecanismo de acomodação do sulco (HAS), disco duplo desencontrado (DD) e disco ondulado (DO). Em Santa Maria, foi adicionado o tratamento semeadura em camalhão com haste (CA). Os seguintes parâmetros foram avaliados: densidade, porosidade e macroporosidade do solo; resistência do solo à penetração mecânica (RP); distribuição do sistema radicular; e produtividade de grãos. Em Formigueiro, os tratamentos ESC, HS e HAS resultaram em menor densidade e maior macroporosidade do solo, nas camadas de 0,05-0,10 e 0,10-0,20 m. A RP foi menor no tratamento ESC e no sulco da HS até 0,15 m, onde as raízes se desenvolveram melhor. A produtividade de grãos de milho em Planossolos é maior quando a semeadura é realizada sobre camalhão, solo escarificado ou semeadura direta, com haste sulcadora na semeadora.Termos para indexação: Zea mays, camada compactada, camalhão, haste sulcadora, rotação de culturas, semeadura direta. Deep tillage and furrow opener seeders for corn cropping in PlanosolsAbstract -The objective this work was to evaluate deep tillage and different furrow opener seeders for growing corn in Planosols. Two experiments were carried out in the field, in two different locations: Santa Maria and Formigueiro, in the state of Rio Grande do Sul, Brazil. A randomized complete block experimental design was used, with four replicates, and treatments of deep tillage (DP) and no-till, using different seed-furrow openers: shank (SH); shank plus furrow accommodation mechanism (SHA); double disk (DD); and notched disk (ND). In Santa Maria, the raised-bed treatment using shank was added (RBS). The following parameters were evaluated: soil bulk density, porosity, and macroporosity; soil penetration resistance (RP); root system distribution; and grain yield. In Formigueiro, the DP, SH, and SHA treatments resulted in lower bulk density and higher soil macroporosity in the 0.05-0.10 and 0,10-0.20-m soil depths. The RP was lower in the DP treatment and in the furrow of the SH treatment until 0.15 m, where roots developed better. Corn grain yield in Planosols is greater when sowing is carried out using raised bed, deep tillage, or no-till using shank in the seeder.
-The objective of this work was to evaluate methods of thermal time calculation and the duration of the development stages of lowland rice (Oryza sativa) irrigated by sprinkling. The experiment was conducted during three growing seasons (2010/2011, 2011/2012, and 2014/2015), with five irrigation water depths, six cultivars, and four replicates. Six methods of thermal time calculation were tested: two using the minimum basal temperature; two using the minimum and optimum temperatures; and two using the minimum, optimum, and maximum basal temperatures. For the thermal time calculation, the crop development cycle was divided into the vegetative, reproductive, and grain-filling phases. The methods that used the three cardinal temperatures showed the lowest coefficients of variation for most of the developmental phases. Both irrigation water depths and rice cultivars affected the thermal time of the development stages. The greater the water availability, the lower the duration of the development cycle. Thermal time values depend on the calculation method.
The objective of this work was to evaluate the effect of raised seedbeds associated with irrigation on the yield of soybean (Glycine max) rotated with rice (Oryza sativa) in lowland conditions in Southern Brazil. Field experiments were conducted in two crop seasons (2014/2015 and 2015/2016), with two planting systems (raised seedbed and flat planting) and two irrigation managements (irrigated and nonirrigated). Water use, biological nitrogen fixation, and yield were evaluated. The water used for raised seedbeds was 14% (151 m3 ha-1) and 27% (163 m3 ha-1) lower than that for flat planting in the first and second crop seasons, respectively. Irrigation increased nodule number per plant, nodule dry weight, and biological nitrogen fixation. The average grain yield of the raised seedbed system was 10% (529 kg ha-1) and 9% (362 kg ha-1) higher than that of flat planting in 2014/2015 and 2015/2016, respectively. Irrigation improved yield by 5% (203 kg ha-1) and 7% (265 kg ha-1) in each crop year. The use of raised seedbeds associated with irrigation improves the yield of soybean grown in rotation with rice in lowland in Southern Brazil.
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