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Aerobic respiration declines in the root tissue of soybean plants exposed to waterlogged soil with a low oxygen content, causing metabolic disorders that negatively affect gas exchange and photosynthetic activity, hampering growth and production. As such, this study to investigated daytime gas exchange, relative chlorophyll content, specific leaf area (SLA) and photosynthetic activity curves in response to photosynthetic photon flux density (PPFD) in soybean plants grown under different conditions: no stress (control), shading, waterlogged soil, and waterlogged soil + shading. Soybean plants exposed to either waterlogging or shading and both conditions simultaneously exhibited reduced photosynthesis linked to lower stomatal opening. Plants submitted to shading showed an increase in SLA, quantum yield and photosynthetic rates, while those grown in waterlogged soil, in full sun, exhibited chlorotic leaves and low apparent quantum yield, resulting in low photosynthetic rates under shading and high light levels. Thus, waterlogging and shading in isolation or combined, compromise daytime gas exchange and alter photosynthetic activity in plants. [ABSTRACT FROM AUTHOR]

ABSTRACT: Aerobic respiration declines in the root tissue of soybean plants exposed to waterlogged soil with a low oxygen content, causing metabolic disorders that negatively affect gas exchange and photosynthetic activity, hampering growth and production. As such, this study to investigated daytime gas exchange, relative chlorophyll content, specific leaf area (SLA) and photosynthetic activity curves in response to photosynthetic photon flux density (PPFD) in soybean plants grown under different conditions: no stress (control), shading, waterlogged soil, and waterlogged soil + shading. Soybean plants exposed to either waterlogging or shading and both conditions simultaneously exhibited reduced photosynthesis linked to lower stomatal opening. Plants submitted to shading showed an increase in SLA, quantum yield and photosynthetic rates, while those grown in waterlogged soil, in full sun, exhibited chlorotic leaves and low apparent quantum yield, resulting in low photosynthetic rates under shading and high light levels. Thus, waterlogging and shading in isolation or combined, compromise daytime gas exchange and alter photosynthetic activity in plants.

In the last crop seasons, the complex of late season diseases (CLSD) of soybean (Glycine max L. (Merrill)), has been causing considerable reductions in the crop yield. Currently, there are no cultivars resistant to all pathogens that causes CLSD. The present study evaluated the effect of applying the acibenzolar-S-methyl resistance inducer, alternative products and fungicide on the severity of CLSD in the soybean cultivar BMX Potência RR during the 2013/2014 and 2014/2015 crops, in the field. The treatments for the experiments were: 1 - control (water); 2 - acibenzolar-S-methyl; 3 - calcium; 4 - micronutrients: copper, manganese and zinc; 5 - micronutrients: manganese, zinc and molybdenum; 6 - nitrogen-potassium fertilizer; 7 - Ascophyllum nodosum and 8 - azoxystrobin + cyproconazole with the addition of the adjuvant. Four applications of alternative products and two of fungicide were carried out in both harvests. A diagrammatic scale assessed the severity of CLSD at the phenological stage R7.1. The acibenzolar-S-methyl resistance inducer, alternative products (macro and micronutrients) and A. nodosum had no effect on the severity of CLSD in the two harvests. The fungicide (azoxystrobin + cyproconazole) reduced the severity of CLSD and prevented damage to productivity in both experiments. [ABSTRACT FROM AUTHOR]

ABSTRACT: In the last crop seasons, the complex of late season diseases (CLSD) of soybean (Glycine max L. (Merrill)), has been causing considerable reductions in the crop yield. Currently, there are no cultivars resistant to all pathogens that causes CLSD. The present study evaluated the effect of applying the acibenzolar-S-methyl resistance inducer, alternative products and fungicide on the severity of CLSD in the soybean cultivar BMX Potência RR during the 2013/2014 and 2014/2015 crops, in the field. The treatments for the experiments were: 1 - control (water); 2 - acibenzolar-S-methyl; 3 - calcium; 4 - micronutrients: copper, manganese and zinc; 5 - micronutrients: manganese, zinc and molybdenum; 6 - nitrogen-potassium fertilizer; 7 - Ascophyllum nodosum and 8 - azoxystrobin + cyproconazole with the addition of the adjuvant. Four applications of alternative products and two of fungicide were carried out in both harvests. A diagrammatic scale assessed the severity of CLSD at the phenological stage R7.1. The acibenzolar-S-methyl resistance inducer, alternative products (macro and micronutrients) and A. nodosum had no effect on the severity of CLSD in the two harvests. The fungicide (azoxystrobin + cyproconazole) reduced the severity of CLSD and prevented damage to productivity in both experiments.

This study aimed to evaluate the effect of different microwave-roasting timeson different sizes of soybean grains with black tegument to achieve the best crunchiness, flavor, and hardness. Black soybean dragées-containing a soybean core coated with layers of chocolate (dragée) - were manufactured, and their nutritional value, microbiological risk, acceptability, and consumer-purchase intentions were verified. Flavor and crunchiness of the roasted black soybeans wereonly affected by the roasting time in the microwave, whereas the hardness was only affected by grain size. The best core of the dragéewas obtainedusing grains ofsieve size 15 (large grains) roastedin the microwave for 11 min; this core presented higher frequencies for extremely crunchy notes (56%), toasted flavor (61%), and an instrumental hardness close to that of the existing commercial product (33.17 N). The manufactured dragées did not present resistant starch, anthocyanins, and microbiological risk, and they were sensorially accepted by the tasters (mean scores of 7.77 for texture and 8.36 for appearance on a scale of 1 to 9). Thus, roasted black soybean dragéeshave a high marketing potential from technological, nutritional, and sensorial points of view. [ABSTRACT FROM AUTHOR]

ABSTRACT: The presence of a compacted soil layer near the ground surface in paddy fields may limit the growth and development of soybean roots. The objective of this study was to evaluate different planting management systems and irrigation on growth and development of soybean root systems in lowland area. The experiment was carried out in 2013/14 and 2014/15 crop seasons in randomized complete block design with factorial treatment (3x2), with four replications. The treatments consisted of different planting management systems: sowing with double disc (A1); sowing with shank (A2) and deep tillage + sowing with double disc (A3), and irrigation: irrigated (D1) and non irrigated (D2). Planting management systems and irrigation influenced the growth of soybean roots. When double disc was used, roots have lower growth and increase in diameter. Use of shanks and deep tillage provide increased growth and development of soybean roots and greater depth distribution. An additional 55mm of irrigation during the V4 soybean development stage provides increased surface area and root volume in when the soil moisture reaches values below 60% of field capacity.

ABSTRACT: In the last few cropping seasons, some soybean producers have tested the application of a hill drop sowing method, usually from three to four seeds every 30 to 40cm. However, there is a lack of information in the literature about the effect of this practice on soybean performance. Thus, the objective of this study was to evaluate the effect of a hill drop sowing with different number of plants per hole on soybean performance. The study was conducted in Londrina - PR, Brazil, during the 2013/14, 2014/15 and 2016/17 cropping seasons. The experiment was a randomized complete block design with four replications and a 2x5 factorial scheme. The first factor consisted of two soybean cultivars, BRS 359RR and NK 7059RR analyzed in the first two cropping seasons and BRS 359RR and BRS 1010IPRO in the last cropping season. The second factor was constituted by five in-hill hole-spacing treatments (HS) (8, 16, 24, 32 and 40cm), with rows spaced 50cm apart. To maintain the same plant density in all treatments (270,000 plants ha-1), sowing was performed manually, being then thinned out. After thinning, the distribution was one plant per hole at HS8, 2 plants at HS16, 3 plants at HS24, 4 plants at HS32, and 5 plants at HS40. The agronomic performance of soybean in hill drop sowing with different number of plants per hole is similar to that of an equidistant distribution of plants.

ABSTRACT: This study investigated the effects of soil management systems, tillage, and application of gypsum agricultural to soil, on soybean development in lowland areas. The experiment was carried out on an Alfisol in a randomized complete block design in a factorial arrangement. The two soil tillage practices were without deep tillage and with deep tillage. Gypsum treatments were no gypsum application, 500kg of gypsum ha-1, 1000kg of gypsum ha-1, and 1500kg of gypsum ha-1. Deep tillage resulted in less soil resistance to root penetration during ryegrass cultivation during the soybean offseason, 11 months after applying the management treatments, resulting in higher dry mass of ryegrass in the offseason and higher soybean yield in the following year.

O objetivo do trabalho foi caracterizar o metabolismo primário, com ênfase na atividade fotossintética, de plantas de soja sob diferente disponibilidade hídrica. O experimento foi conduzido em câmara de crescimento com plantas jovens de soja cv. BMX Apolo RR, cultivadas sem restrição hídrica até o estádio de seis folhas trifolioladas expandidas e a sétima folha aberta.Foram estudados cinco níveis de disponibilidade hídrica(-0,004, -0,006, -0,026, -0,042 e -0,164MPa) com oito vasos (repetições) por tratamento. Avaliou-se a assimilação líquida de carbono (AL), condutância estomática (gs) e transpiração (E) na sexta folha de uma planta de cada vaso. Foi determinado o potencial da água na folha, fluorescência da clorofila,conteúdo de clorofila (a, b e total), rendimento quântico e caracterizado o crescimento vegetativo. Potenciais da água no solo de -0,026 MPa comprometem a assimilação líquida de carbono de plantas de soja em função da redução da condutância estomática. Os potenciais aplicados não influenciam na quantidade de pigmentos fotossintéticos e no crescimento vegetativo em situações de breve exposição ao estresse.

In the last few cropping seasons, some soybean producers have tested the application of a hill drop sowing method, usually from three to four seeds every 30 to 40cm. However, there is a lack of information in the literature about the effect of this practice on soybean performance. Thus, the objective of this study was to evaluate the effect ofa hill drop sowing with different number of plants per hole on soybean performance. The study was conducted in Londrina - PR, Brazil, during the 2013/14, 2014/15 and 2016/17 cropping seasons. The experiment was a randomized complete block design with four replications and a 2x5 factorial scheme. The first factor consisted of two soybean cultivars, BRS 359RR and NK 7059RR analyzed in the first two cropping seasons and BRS 359RR and BRS 1010IPRO in the last cropping season. The second factor was constituted by five in-hill hole-spacing treatments (HS) (8, 16, 24, 32 and 40cm), with rows spaced 50cm apart. To maintain the same plant density in all treatments (270,000 plants ha-1), sowing was performed manually, being then thinned out. After thinning, the distribution was one plant per hole at HS8, 2 plants at HS16, 3 plants at HS24, 4 plants at HS32, and 5 plants at HS40. The agronomic performance of soybean in hill drop sowing with different number of plants per hole is similar to that of an equidistant distribution of plants. [ABSTRACT FROM AUTHOR]

This study investigated the effects of soil management systems, tillage, and application of gypsum agricultural to soil, on soybean development in lowland areas. The experiment was carried out on an Alfisol in a randomized complete block design in a factorial arrangement. The two soil tillage practices were without deep tillage and with deep tillage. Gypsum treatments were no gypsum application, 500kg of gypsum ha-1, 1000kg of gypsum ha-1, and 1500kg of gypsum ha-1. Deep tillage resulted in less soil resistance to root penetration during ryegrass cultivation during the soybean offseason, 11 months after applying the management treatments, resulting in higher dry mass of ryegrass in the offseason and higher soybean yield in the following year. [ABSTRACT FROM AUTHOR]

Com a constante evolução tecnológica, a indústria sementeira exige cada vez mais rapidez na identificação da qualidade fisiológica das sementes. Nesse sentido, o trabalho teve por objetivo avaliar a eficiência e rapidez do método de Pettenkofer na determinação da atividade respiratória para diferenciar o vigor de cinco lotes de sementes de soja cv. 'Taura'. Além da determinação da atividade respiratória, foram realizados testes de germinação em areia, condutividade elétrica, comprimento de parte aérea e raiz, massa seca da parte aérea, das raízes e massa seca total. Os resultados dos testes de qualidade fisiológica e da atividade respiratória das sementes permitiram a classificação dos lotes em diferentes níveis de qualidade fisiológica, sendo que a determinação da atividade respiratória, pelo método de Pettenkofer, é eficiente, rápida e útil como alternativa na diferenciação do vigor de lotes de sementes de soja.The seed industry with the constant technological developments increasingly requires quick identification of seed quality. Therefore, this study aimed to evaluate the efficiency and speed of the Pettenkofer method for the breathing activity determination in order to distinguish the effect of the vitality of seeds. Five seed lots of soybean cv. 'Taura' were used. Besides the determination of the breathing activity, the following benchmark tests were performed: moisture content, germination, electrical conductivity, shoot length, root and total dry mass. The results of benchmark tests and breathing activity of seeds allowed the classification of the lots at different levels of vitality. The determination of breathing activity by the Pettenkofer method is efficient, fast and useful as an alternative test to distinguish soybean seed lots.

O objetivo deste trabalho foi estimar o tamanho de amostra necessária para avaliar caracteres de genótipos de soja (Glycine max L.) e verificar a variabilidade do tamanho de amostra entre genótipos e entre experimentos. Para tanto, 28 genótipos de soja foram avaliados em cinco experimentos conduzidos em Jaboticabal, Estado de São Paulo (latitude 21°15'22"S, longitude 48°18'18" W e 595m de altitude), nos anos agrícolas de 2002 a 2005. Foi utilizado o delineamento de blocos ao acaso, com três repetições, e foram avaliados os caracteres altura de planta na maturação e de inserção de primeira vagem, número de nós por planta, de ramos por planta e de vagens por planta em seis plantas amostradas aleatoriamente na parcela. Há variabilidade da estimativa do tamanho de amostra entre genótipos quanto ao número de nós por planta e entre experimentos quanto à altura de planta na maturação, ao número de nós por planta, de ramos por planta e de vagens por planta. Para melhorar a precisão da avaliação de caracteres em plantas de soja, deve-se usar maior número de repetições e, pelo menos, 12 plantas por unidade experimental.The aim of this research was to determine the sample size of characters in different soybeans (Glycine max L.) genotypes and to verify its variability among genotypes and experiments. Twenty-eight soybeans genotypes were evaluated in five experiments conducted in Jaboticabal, São Paulo State, Brazil (latitude 21°15'22"S, longitude 48°18'18" W, altitude 595m), in agricultural years from 2002 to 2005. Randomized blocks design with three repetitions was installed to evaluate the following characters: plant height at maturity, height of first pod insertion, number of nodes per plant, number of branches per plant and number of pods per plant, in six plants sampled at random in each plot. It was found variability in the sample size among genotypes in relation to the number of nodes per plant. When the five experiments were compared, results also show variability of the sample size in relation to plant height at maturity, number of nodes per plant, number of branches per plant and number of pods per plant. To improve the experimental precision in the evaluation of characters in soybeans plants it is recommended to increase the number of repetitions and use, at least, twelve plants per plot.

Neste trabalho, foram utilizados dados de produtividade de grãos de 216 ensaios de genótipos de soja, realizados no Estado do Rio Grande do Sul, nos anos agrícolas 2003/2004, 2004/2005 e 2005/2006. O objetivo foi verificar se o uso do método de Papadakis reduz o número de repetições necessário à predição do desempenho de genótipos de soja em relação à produtividade de grãos. Maior precisão experimental é obtida com a aplicação do método de Papadakis, independentemente da combinação entre o tamanho de parcela e o número de repetições e a homogeneidade entre os blocos. O uso do método de Papadakis permite reduzir o número de repetições necessário à predição do desempenho de genótipos de soja, para um mesmo grau de precisão, em relação à produtividade de grãos. Ensaios com quatro repetições e analisados com o método de Papadakis possibilitam a identificação de genótipos superiores de soja em relação à produtividade de grãos, com 80% de precisão.Seed yield data of 216 soybean genotype experiments conducted on of Rio Grande do Sul-Brazil during the 2002/2004, 2004/2005 and 2005/2006 were used in order to verify whether the use of Papadakis Method would decrease the number of replications necessary to predict the performance of soybean genotypes in regard to seed yield. Greater experimental precision can be obtained by using the Papadakis Method regardless the combination among plot size, number of replications and block homogeneity. The use of Papadakis Method allows reduction of replications necessary to predict seed yield performance of soybean genotypes. Experiments consisted of four replications and were analyzed according to Papadakis Method which permitted to identify superior genotypes in regard to seed yield with 80% of precision.

As pontas de pulverização são um dos componentes mais importantes dos pulverizadores hidráulicos para aplicação de agrotóxicos. O presente trabalho teve como objetivo avaliar o controle químico da ferrugem asiática e a deposição da calda fungicida aplicada na cultura da soja, em função de diferentes volumes de aplicação e de tipos de ponta de pulverização. O ensaio foi conduzido no delineamento em blocos ao acaso, com quatro repetições, em esquema bifatorial (4 x 2) + 1: quatro tipos de ponta de pulverização (jato plano padrão, jato plano de pré-orifício, jato plano de indução de ar e jato plano duplo de indução de ar), dois volumes de aplicação (115 e 160L ha-1) e um tratamento adicional, que não recebeu fungicida (testemunha). Realizou-se a semeadura direta da cultivar "Emgopa 313" (ciclo tardio), avaliando-se, após a aplicação do fungicida tebuconazole com as diferentes pontas e volumes, a deposição de calda no dossel da cultura, a severidade da ferrugem e a produtividade. Constatou-se que, apesar de o volume de calda de 160L ha-1 e de a utilização da ponta de jato plano padrão terem proporcionado maior uniformidade de distribuição da calda fungicida nas plantas, não houve influência do tipo de ponta de pulverização e do volume de aplicação no controle da ferrugem e na produtividade da cultura da soja. O fungicida tebuconazole propiciou bom controle da ferrugem, refletindo na produtividade de grãos, que foi, em média, 41% superior à obtida na testemunha.The spray nozzles are one of the most important components of pesticide hydraulic sprayers. This study aimed at evaluating the chemical control of the rust and the deposition of fungicide sprayed on soybean concerning different nozzles, and application volumes. A randomized complete-block design with four replications was used, in a factorial model (4 x 2) + 1: four spray nozzles (standard flat fan, pre-orifice flat fan, air induction flat fan and air induction twin flat fan), two spray volumes (115 and 160L ha-1) and the control (non-treated plot). Emgopa 313 soybean (long cycle) were sown. After the application of the fungicide tebuconazole, with the different nozzles and volume rates, the spray deposition in the plant canopy, the rust severity, and the yield were evaluated. The results showed that, despite the fact of the volume rate of 160L ha-1 and of the use of the standard flat fan nozzles have provided larger fungicide distribution uniformity in the plant canopy, there was not influence of the nozzle type neither of the application volume in the control of the rust as well as in the soybean yield. The fungicide has provided a good control of the rust, increasing the soybean yield, that was, on average, 41% superior to that obtained in the control.

The presence of a compacted soil layer near the ground surface in paddy fields may limit the growth and development of soybean roots. The objective of this study was to evaluate different planting management systems and irrigation on growth and development of soybean root systems in lowland area. The experiment was carried out in 2013/14 and 2014/15 crop seasons in randomized complete block design with factorial treatment (3x2), with four replications. The treatments consisted of different planting management systems: sowing with double disc (A1); sowing with shank (A2) and deep tillage + sowing with double disc (A3), and irrigation: irrigated (D1) and non irrigated (D2). Planting management systems and irrigation influenced the growth of soybean roots. When double disc was used, roots have lower growth and increase in diameter. Use of shanks and deep tillage provide increased growth and development of soybean roots and greater depth distribution. An additional 55mm of irrigation during the V4 soybean development stage provides increased surface area and root volume in when the soil moisture reaches values below 60% of field capacity. [ABSTRACT FROM AUTHOR]

A lagarta-da-soja, Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae), é uma praga importante na cultura da soja no Brasil. Este estudo teve como objetivo avaliar diferentes inseticidas, reguladores de crescimento, para o controle dessa praga. Os inseticidas diflubenzuron (15g i.a. ha-1), lufenuron (7,5g i.a. ha-1), metoxifenozide (21,6g i.a. ha-1) e teflubenzuron (7,5g i.a. ha-1) foram aplicados com pulverizador costal de precisão, equipado com pontas tipo leque 110, 02, numa pressão de 1 bar e volume de calda de 100l ha-1. No dia da aplicação dos inseticidas, as plantas de soja (cv. Fundacep 33) estavam com 0,90m de altura, no estádio R3.1, e infestação média de 95 lagartas pequenas e de 33 lagartas grandes por dois metros de fileira. A eficiência dos inseticidas foi determinada através da contagem do número de lagartas vivas pequenas e grandes aos 0, 2, 4, 7 e 10 dias após a aplicação (DAA); da percentagem de desfolha aos 15 DAA e da produção de grãos. Foi observado efeito de choque do inseticida metoxifenozide tanto em lagartas pequenas quanto em grandes. Os inseticidas diflubenzuron, lufenuron e teflubenzuron controlaram eficientemente as lagartas a partir de 4 DAA. As infestações de lagartas nas parcelas testemunhas aumentaram a desfolha em 75,8% e reduziram produtividade para 2371 kg ha-1. Nas parcelas tratadas com inseticidas desfolha variou de 34,7% a 50,7% e a produtividade entre 3255kg ha-1 e 3585kg ha-1.The velvetbean caterpillar, Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae), is an important soybean pest in Brazil. This study aimed to evaluate growth regulators insecticides. A precision sprayer equipped with 110 02 nozzles, working at a constant pressure of 1 bar and volume of 100 liters per hectare was used to apply the insecticide treatments (diflubenzuron at 15g a.i. per hectare, lufenuron at 7.5 g a.i. per hectare, metoxyfenozide at 21.6g a.i. per hectare and teflubenzuron at 7.5g a.i. per hectare). Applications when plants were 0.90m height, in the R3.1 growth stage, and the number of small larvae was 95, while that of large larvae was 33 per two meters of row. The number of live larvae at 0, 2, 4, 7 and 10 days after application, the defoliation at 15 days after application and grain yield were evaluated. The fastest control of large and small larvae was obtained with metoxyfenozide at 2 days after application. The insecticides diflubenzuron, lufenuron and teflubenzuron efficiently controlled of large and small larvae, but only at 4 days after application. Larval infestations in non-treated plots resulted in significant defoliation and yield losses when compared to plots treated with insecticides.

The aim of the research was to characterize the primary metabolism, with emphasis on photosynthetic activity, of soybean plants under different water availability conditions. The experiment was conducted in growth chamber with young plants of soybean cv. 'BMX Apolo RR' cultivated without water restriction up to the stage of six leaves expanded and the seventh leaf unfolded. Five levels of water availability were studied (-0.004, -0.006, -0.026, -0.042 and -0.164MPa) with eight pots (replications) per treatment. It was evaluated the net carbon assimilation (AL), stomatal conductance (gs) and transpiration (E) of the sixth leaf of one plant per pot. It was determined the water potential leaf, chlorophyll fluorescence, chlorophyll content (a, b and total), quantum yield and it was characterized the vegetative growth. Soil water potential of -0.026 MPa compromises the net carbon assimilation of soybean plants due to reduction of the stomatal resistance. The potentials applied did not influence in the amount of photosynthetic pigments and in the vegetative growth in situations of short exposition to stress. [ABSTRACT FROM AUTHOR]

The seed industry with the constant technological developments increasingly requires quick identification of seed quality. Therefore, this study aimed to evaluate the efficiency and speed of the Pettenkofer method for the breathing activity determination in order to distinguish the effect of the vitality of seeds. Five seed lots of soybean cv. 'Taura' were used. Besides the determination of the breathing activity, the following benchmark tests were performed: moisture content, germination, electrical conductivity, shoot length, root and total dry mass. The results of benchmark tests and breathing activity of seeds allowed the classification of the lots at different levels of vitality. The determination of breathing activity by the Pettenkofer method is efficient, fast and useful as an alternative test to distinguish soybean seed lots. [ABSTRACT FROM AUTHOR]

Seed yield data of 216 soybean genotype experiments conducted on of Rio Grande do Sul-Brazil during the 2002/2004, 2004/2005 and 2005/2006 were used in order to verify whether the use of Papadakis Method would decrease the number of replications necessary to predict the performance of soybean genotypes in regard to seed yield. Greater experimental precision can be obtained by using the Papadakis Method regardless the combination among plot size, number of replications and block homogeneity. The use of Papadakis Method allows reduction of replications necessary to predict seed yield performance of soybean genotypes. Experiments consisted of four replications and were analyzed according to Papadakis Method which permitted to identify superior genotypes in regard to seed yield with 80% of precision. [ABSTRACT FROM AUTHOR]

The aim of this research was to determine the sample size of characters in different soybeans (Glycine max L.) genotypes and to verify its variability among genotypes and experiments. Twenty-eight soybeans genotypes were evaluated in five experiments conducted in Jaboticabal, São Paulo State, Brazil (latitude 21°15'22"S, longitude 48°18'18" W, altitude 595m), in agricultural years from 2002 to 2005. Randomized blocks design with three repetitions was installed to evaluate the following characters: plant height at maturity, height of first pod insertion, number of nodes per plant, number of branches per plant and number of pods per plant, in six plants sampled at random in each plot. It was found variability in the sample size among genotypes in relation to the number of nodes per plant. When the five experiments were compared, results also show variability of the sample size in relation to plant height at maturity, number of nodes per plant, number of branches per plant and number of pods per plant. To improve the experimental precision in the evaluation of characters in soybeans plants it is recommended to increase the number of repetitions and use, at least, twelve plants per plot. [ABSTRACT FROM AUTHOR]