João Leonardo Fernandes Pires

Potencial de rendimento da soja em razão da disponibilidade de fósforo no solo e dos espaçamentos

The experiment was performed during the 1994/95 growing season at the EEA/UFRGS, in Eldorado do Sul, RS, Brazil, in a dark red Podzolic soil (Rhodic Paleudult). The objective was to evaluate the soybean potential yield at the growth stages R2 (flowering), R5 (beginning of pod filling) and R8 (maturity). The treatments were arranged in subplots in a randomized complete block design, and consisted of two soil P levels (3 and 15 ppm), and two row spacings (20 and 40 cm). The early, determinate cultivar OCEPAR 14 was used. On the average of the treatments, potential yield in R2 was of 18 t/ha and of 10 t/ha in R5, and the final yield, in R8 of 4.6 t/ha. The treatment of 15 ppm of P reached greater potential yield in the three growth stages, due to less flower and pod abortion. The row spacing of 20 cm showed greater potential yield at the growth stages evaluated, but the percentage of yield reduction due to flower and pod abortion were similar.

Análise de componentes principais de atributos químicos e físicos do solo limitantes à produtividade de grãos

O objetivo deste trabalho foi avaliar, por meio da analise dos componentes principais, a reducao na dimensionalidade de atributos quimicos e fisicos do solo para a compreensao da variabilidade espacial e temporal da produtividade de culturas de graos. A area experimental, de 54 ha, e manejada em agricultura de precisao ha oito anos. Com base em seis mapas de colheita (soja – safra 2000/2001; milho – 2001/2002; soja – 2002/2003; trigo – 2003; soja – 2003/2004; e milho – 2004/2005), a area foi dividida em tres zonas de produtividade de graos (alta, media e baixa). Foram definidos 15 pontos georreferenciados representativos, para determinacao de atributos quimicos e fisicos do solo, o que totalizou 63 variaveis analisadas. Entre os atributos quimicos, o elevado teor de K no solo e o que melhor explica a variabilidade espacial da produtividade das culturas de graos, provavelmente em razao do desbalanco das relacoes Ca:K e Mg:K. A zona de baixa produtividade apresentou baixa qualidade fisica do solo. Neste caso, a infiltracao de agua no solo, isoladamente, e a variavel que melhor explica o desempenho das culturas de graos. A analise dos componentes principais dos atributos quimicos e fisicos do solo e estrategia eficiente para explicar a variabilidade espacial e temporal da produtividade de culturas de graos.

Aclimatação ao frio e dano por geada em canola

O objetivo deste trabalho foi avaliar a influencia da aclimatacao ao frio sobre o dano causado pela geada em diferentes estadios fenologicos de genotipos de canola. Foram realizados cinco experimentos em ambiente controlado, em 2006, 2007 e 2008. Os fatores avaliados foram: genotipos, aclimatacao (com; sem), intensidades de geada, estadios de desenvolvimento de plantas, regimes de aclimatacao e regimes de geada. As variaveis avaliadas foram: queima de folhas, massa de materia seca, estatura de plantas, duracao de subperiodo, componentes de rendimento e rendimento de graos. A aclimatacao ao frio, antes da geada, resultou em menor queima de folhas e maior massa de materia seca, em comparacao a plantas nao aclimatadas. As geadas foram prejudiciais a partir de -6°C no inicio do ciclo de desenvolvimento, principalmente em plantas nao aclimatadas, e a partir de -4oC na floracao, com reducao do numero de siliquas e do numero de graos por siliqua. A aclimatacao apos as geadas nao contribuiu para a tolerância da canola a esse evento. Geadas consecutivas nao acarretaram maior prejuizo a canola. A aclimatacao de plantas de canola antes da geada reduz os danos, principalmente quando a geada ocorre no inicio do desenvolvimento das plantas.

Estimativa do potencial de rendimento por estrato do dossel da soja, em diferentes arranjos de plantas

The soybean yield potential can be modified by plant arrangement. This modification might be the result of the diferential contribution of the canopy strata for the potential determination. The experiment was conducted at the Agronomic Experimental Estation of the Universidade Federal do Rio Grande do Sul, in Eldorado do Sul, Rio Grande do Sul, Brazil, in the 2000/01 growing season. The objectives were to evaluate the yield potential by stratum of soybean canopy in different plant arrangement, under two water availability. The cultivar tested was BRS 137, in no-till planting. Water availability (irrigated an no irrigated), row spacing (20 and 40cm) and population levels (20, 30 and 40 plants m-2) were tested. The yield potential was estimated in the beginning of grain filling (R5). It was considered that all flowers and pods present at this stage were able to reach maturation, forming grains and contributing to yield. The canopy was divided in three strata by plans paralel to soil surface. The irrigated treatment (14976kg ha-1) presented larger total plant yield potential and yield in R8 (maturity) than without irrigation (12148kg ha-1), similar to what ocurred in all soybean canopy strata. The plant arrangement with 20cm of row spacing, independent of population, presented, on the average, larger yield potential in R5 (14970kg ha-1) compared to 40cm row spacing (12154kg ha-1). The same was also noticed at the medium soybean canopy stratum. At maturity the plant arrangement 20cm of row spacing and population of 20 plants m-2 yielded more than 40cm (6442kg ha-1 compared to 4396kg ha-1), due to larger yield at the medium and botom stratum. There was a linear decrease in yield potential with increase of plant population, with row spacing reduction (20cm), explained by the same behavior of the canopy strata. Similar response was obtained for yield in R8. The soybean canopy strata contributed differently to yield potential with the plant arrangement modification, due to the diferential number of reproductives structures (R5) and yield components (R8) alteration.

Tolerância da soja ao desfolhamento afetada pela redução do espaçamento entre fileiras

The row spacing reduction from 40 to 20 cm increase radiation interception, leaf area index and grain yield. This experiment aimed to evaluate if the row spacing reduction influence soybean tolerance to loss of photosynthetic area. The research was performed using no-till tillage system at the Agronomic Experimental Station of Universidade Federal do Rio Grande do Sul, during the 2000/01 growing season. Treatments were arranged in a split-split plot randomized complete block design, with four replications. Treatments included five combination of defoliation in three stages of development (V9 - ninth-node, R2 - full bloom and R5 - beginning of seed filling), two row spacings (20 and 40cm) and four defoliation levels (0 - control, 33, 67 and 100%). The cultivar tested was FT-Abyara. Defoliations performed at the reproductive stages decrease grain yield, especially when curried at the begging of grain filling (R5). The control grain yield was 21% higher when soybean was sown with rows 20cm apart (4134kg ha-1) than with 40cm rows (3413kg ha-1). Narrow rows always provided higher yields in all defoliation levels. The component that influenced yield the most was the number of pods m-2. These results indicate that row spacing reduction from 40cm to 20cm is a positive management strategy for soybean production regardless of defoliation level.

Qualidade de grãos de duas cultivares de soja em função da disponibilidade de água no solo e arranjo de plantas

The soybean is a crop with high demand for nitrogen (N) due to the grain protein content of about 40%. Because of the high protein, soybean is of great economic importance. The present study had its objectives to determine the effect of water availability and soybean plant arrangement on grain quality of two cultivars. With this objective, an experiment was performed during the 1998/99 growing season, in the Agronomic Experimental Station of the Federal University of Rio Grande do Sul (EEA/UFRGS), Eldorado do Sul, RS. The treatments were arranged in a randomized complete-block in a split split-plot design, with four replications. Two water availability (irrigated and not irrigated), two cultivars (BRS 137 and BRS 138) and three row spacings (20cm, 40cm and 20-40cm in skip row) were tested. The leaf N content was evaluated during crop growth, and the protein and oil content, as well as the size and weight of the grains, at the harvest. The average grain yield was of 3360kg ha -1 . The irrigation increased grain yield by 1101kg ha -1 (39%), due to the increase in leaf N, size and weight of the grain. The yield of the cultivar BRS 137 was 535kg ha -1 (17%) greater, as well as it produced grains with larger size, weight and protein content than BRS 138. In the late reproductive stage, leaf N was higer in 20cm and 40cm, what resulted in larger protein content and grain yield 18 and 13% higher, compared to 20-40 cm in skip row, respectively. The grain oil content was not altered by the treatments.

BRS 374 - wheat cultivar

BRS 374 is a wheat cultivar developed by Embrapa. It resulted from a cross between the F1 generation of PF 88618/Coker80.33 and Frontana/Karl. BRS 374 belongs to the soft wheat class, has a low plant height, a high potential grain yield, and white flour.

Rendimento de grãos e características agronômicas de soja em função de sistemas de rotação de culturas

The effects of crop rotation systems (CRS) on soybean yield and agronomic characteristics were evaluated from 1996/1997 to 2010/2011 at Embrapa Trigo, Passo Fundo (RS), Brazil. Four soil management systems (SMS) were compared, namely: 1) no tillage, 2) minimum tillage, 3) conventional tillage using a disk plow and a disk harrow, and 4) conventional using a moldboard and a disk harrow and three CRS: system I (wheat/soybean), system II (wheat/soybean and common vetch/corn or sorghum) and system III (wheat/soybean, white oats/soybean and common vetch/corn or sorghum). This is a split-plot, randomized, complete block design with three replications. SMS were assigned in the main plot and CRS systems in the split-plots. This work addressed only data on crop rotation systems. There were no significant differences between the CRS for number of grains per plant, 1,000 grain weight and first pod height in soybean. The crop rotation for a summer, with corn or sorghum, propitiates a higher soybean yield compared with the other systems and monoculture soybean. The combination of conservation systems (no tillage and minimum tillage) and CR resulted in a higher soybean yield. The lowest grain yield and grain weight per plant were obtained in monoculture soybean.

Métodos para a estimativa do potencial de rendimento da soja durante a ontogenia

O objetivo deste trabalho foi estudar metodos para a estimativa do potencial de rendimento da soja durante a ontogenia. Os experimentos foram realizados em Eldorado do Sul, RS, durante as safras de 1996/1997, 1999/2000 e 2000/2001. Os tratamentos constaram de cinco cultivares de soja, FT-Saray, IAS 5, IAS 4, FT-Abyara e FEPAGRO RS-10. Cinco metodos foram utilizados para estimar o rendimento que seria obtido se todas as estruturas reprodutivas presentes no florescimento e no inicio do enchimento de graos, produzissem graos na maturacao. O potencial de rendimento no florescimento e no enchimento de graos, apresentou alta correlacao com o numero de flores e estruturas reprodutivas, respectivamente. Verificou-se, tambem, correspondencia entre os metodos. Nao houve, na maioria das vezes, correlacoes significativas entre o potencial, no florescimento e enchimento de graos, e o rendimento de graos na maturacao. Os metodos estudados constituem ferramentas importantes para o manejo, quando utilizados para comparar o potencial de rendimento durante a ontogenia.

Resposta do trigo BRS Guamirim à aplicação de Azospirillum, nitrogênio e substâncias promotoras do crescimento

Substâncias e microrganismos promotores do crescimento vegetal tem sido disponibilizados aos produtores rurais visando aumentar o rendimento das culturas. Este trabalho objetivou avaliar doses de nitrogenio e produtos contendo microrganismos e/ou substâncias promotoras do crescimento sobre os componentes de rendimento e produtividade da cultivar de trigo BRS Guamirim; bem como avaliar se a adicao complementar de N, com ureia, e eficaz na manutencao de maior rendimento de trigo inoculado com Azospirillum brasilense e se esta inoculacao pode substituir total ou parcialmente a adubacao nitrogenada do trigo. O experimento foi conduzido em Coxilha/RS, na safra de 2014. O delineamento experimental foi de blocos casualizados, com quatro repeticoes. Nove tratamentos compuseram o estudo: uma testemunha; quatro produtos (Azospirillum brasilense, hormonio vegetal sintetico, estimulador vegetal mineral e biofertilizante); um tratamento com uso simultâneo dos quatro produtos; e tres doses adicionais de nitrogenio (0, 40 e 120 kg ha-1) associadas com Azospirillum. A cultivar de trigo foi avaliada quanto ao rendimento de graos, componentes do rendimento, indice de colheita aparente, peso hectolitrico, materia seca e conteudo de N na parte aerea, e indice de vegetacao. Os produtos avaliados, contendo microrganismos e/ou substâncias promotoras do crescimento, nao alteram o rendimento de graos de trigo na ausencia de deficiencias hidrica e nutricional. O Azospirillum brasilense nao substitui total ou parcialmente a adubacao nitrogenada da cultivar de trigo BRS Guamirim.