ABSTRACT The study of competitive interactions between crops and weeds can be an important tool in integrated weed management. The objective of this work was to evaluate the competitive ability of maize hybrids in the presence of hairy beggarticks, testing different proportions of plants in the associations. For maize hybrids (Dekalb 230 PRO3, Pioneer 30F53 VYH, Brevant 2B433 PW, and Syngenta 505 VIP3) and for hairy beggarticks, the final density was 20 individuals pot-1, which was determined in preliminary experiments. Experiments were carried out on a substitutive series, on different combinations of the species, varying the relative proportions (100:0, 75:25, 50:50, 25:75, and 0:100%). The analysis of species competitiveness was performed using diagrams applied to the substitutive experiments and relative competitiveness indices. The maize hybrids showed less loss when reducing the morphological variables of the hairy beggarticks and demonstrated superiority in competitive ability in relation to the weed. Competition occurred between maize hybrids in the presence of hairy beggarticks, being negatively affected, regardless of the proportion of plants, causing reductions in plant height, stem diameter, leaf area, and dry mass. An average reduction of 10% and 86% of the MS of maize hybrids and weed was observed, respectively, when comparing the absence of competition with any associated densities, intraspecific competition being more harmful than interspecific. Maize hybrids and hairy beggarticks compete for the same environmental resources, with the crop being more competitive than the competitor.

RESUMO O estudo das interações competitivas entre espécies cultivadas e não cultivadas pode ser uma ferramenta importante no manejo integrado de plantas daninhas. O objetivo deste trabalho foi avaliar a habilidade competitiva de híbridos de milho na presença do picão-preto, testando-se diferentes proporções de plantas nas associações. Tanto para os híbridos de milho (Dekalb 230 PRO3, Pioneer 30F53 VYH, Brevant 2B433 PW e Syngenta 505 VIP3) quanto para o picão-preto, a densidade final foi de 20 indivíduos vaso-1, determinada em experimentos preliminares. Após foram instalados ensaios em série de substituição, nas diferentes combinações das espécies, variando-se as proporções relativas (100:0, 75:25, 50:50, 25:75 e 0:100%). A análise da competitividade das espécies foi efetuada por meio de diagramas aplicados a experimentos substitutivos e pelos índices de competitividade relativa. Os híbridos de milho apresentaram menor perda ao reduzirem as variáveis morfológicas do picão-preto e demonstraram superioridade na habilidade competitiva em relação a planta daninha. Ocorreu competição entre os híbridos de milho na presença do picãopreto, sendo afetados negativamente, independentemente da proporção de plantas, provocando reduções na estatura de plantas, diâmetro de caule, área foliar e massa seca. Observou-se redução média de 10 e 86% da MS dos híbridos de milho e da planta daninha, respectivamente ao se comparar a ausência de competição com qualquer das densidades associadas, sendo a competição intraespecífica mais prejudicial do que a interespecífica. Os híbridos de milho e o picão-preto competem pelos mesmos recursos do meio, sendo a cultura mais competitiva do que a planta daninha.

ABSTRACT Ryegrass and turnip are weeds that cause high yield losses when infesting barley, thus requiring adequate management. In this context, the aim of this study was to evaluate the selectivity of different herbicide treatments and weed control in the barley crop, cultivar BRS Cauê. Two field experiments were conducted in randomized blocks, with four replications. The treatments used were: pendimethalin (800 g·ha-1), sulfentrazone + diuron (175 + 350 g·ha-1), and imazaquim (150 g·ha-1 of a. e.) applied pre-emergence; and iodosulfuron (3.5 g·ha-1), pyroxsulam (18 g·ha-1), metsulfuron-methyl (3.96 g·ha-1), 2,4-D (670 g·ha-1 of a. e.), clodinafop-propargyl (48 g·ha-1), bentazon + imazamox (600 + 28 g·ha-1), saflufenacil (49 g·ha-1), bentazon (720 g·ha-1), carfentrazone-ethyl (120 g·ha-1), and imazamox (42 g·ha-1) applied post-emergence, with two controls (one weeded and the other infested). The use of the herbicide imazaquim caused high levels of phytotoxicity in barley. Gas exchange was less responsive to herbicide applications in relation to barley phytotoxicity and productivity. Clodinafop-propargil showed the best control of ryegrass, while the herbicides iodosulfuron, pyroxsulam, metsulfurom-methyl, 2,4-D, bentazon + imazamox, saflufenacil, bentazon, carfentrazone-ethyl, and imazaquim showed high efficiency in the control of turnip species. Imazaquim caused reduction of up to 74.7% in barley grain yield. On the other hand, iodosulufuron and piroxsulam allowed the highest grain yields of the barley cultivar, BRS Cauê, by promoting partial control of ryegrass and total control of turnip species, followed by clodinafop-propargyl and metsulfuron-methyl, which controlled ryegrass and turnip, respectively, allowing an increase in yield grain in relation to the infested control.

Resumen El objetivo de este estudio fue evaluar la interferencia y determinar el nivel de daño económico (NDE) de escoba dura infestando diferentes cultivares de soja. Los tratamientos fueron cultivares de soja (NS 6909, NA 5909, DM 5958, Brasmax ELITE, Brasmax LANÇA y SYN 13561) y las densidades de escoba dura (0, 2, 3, 4, 9, 15, 16, 23, 22 y 58; 0, 2, 3, 3, 6, 6, 10, 11, 18 y 47; 0, 3, 4, 7, 8, 10, 11, 13, 15 y 24; 0, 1, 4, 6, 12, 18, 19, 31, 44 y 50; 0, 4, 5, 6, 9, 13, 17, 20, 20 y 47; e 0, 2, 3, 5, 9, 11, 15, 18, 29 y 30 plantas m-2), respectivamente, para cada cultivar. Los cultivares NS 6909, NA 5909 y Brasmax Lança son más competitivos que DM 5958, Brasmax Elite y SYN 13561. Los valores de NDE varían de 0,55 a 0,95 plantas m-2 para los cultivares NS 6909, NA 5909 y Brasmax Lança, que mostraron mejor competitividad. Los valores más bajos de NDE varían de 0,26 a 0,61 plantas m-2 para los cultivares DM 5958, Brasmax Elite y SYN 13561, los cuales mostraron menor competitividad con la maleza.

Abstract This study aimed to assess the interference and threshold level (TL) of Sida rhombifolia, the arrowleaf sida, competing with different soybean cultivars. The treatments comprised different soybean cultivars (NS 6909, NA 5909, DM 5958, Brasmax ELITE, Brasmax LANÇA, and SYN 13561) and densities of arrowleaf sida plants per square meter (m-2) (0, 2, 3, 4, 9, 15, 16, 23, 22, and 58; 0, 2, 3, 3, 6, 6, 10, 11, 18, and 47; 0, 3, 4, 7, 8, 10, 11, 13, 15, and 24; 0, 1, 4, 6, 12, 18, 19, 31, 44, and 50; 0, 4, 5, 6, 9, 13, 17, 20, 20, and 47; 0, 2, 3, 5, 9, 11, 15, 18, 29, and 30, respectively) for each cultivar. Cultivars NS 6909, NA 5909, and Brasmax Lança were more competitive than DM 5958, Brasmax Elite, and SYN 13561. The TL values varied from 0.55 to 0.95 plants m-2 for cultivars NS 6909, NA 5909, and Brasmax Lança, which exhibited greater competitiveness with arrowleaf sida. The lowest values of TL varied from 0.26 to 0.61 plants m-2 for cultivars DM 5958, Brasmax Elite, and SYN 13561, which had less competitiveness with weed.

Resumen El objetivo de este trabajo fue evaluar la capacidad competitiva de cultivares de frijol tipo carioca, BRS FC104, BRS FC402, IAC Imperador, IAC Milênio, IPR Tangará y SCS Riqueza, bajo niveles crecientes de infestación de Alexandergrass (Urochloa plantaginea). Los experimentos se realizaron en condiciones de invernadero en un diseño completamente al azar con cuatro repeticiones. Los tratamientos se organizaron en proporciones de plantas de frijol y Alexandergrass de: 100: 0, 75:25, 50:50, 25:75 y 0: 100 o 40:00, 30:10, 20:20, 10:30 y 0: 40 plantas por maceta. El análisis de la competitividad de las especies se realizó mediante diagramas aplicados a experimentos de series de reemplazo y también mediante los índices de competitividad relativa. Treinta días después de la emergencia del cultivo, se midieron el área foliar (AF), la altura de la planta (AP), el diámetro de la planta (DP) y la masa seca de los brotes (MS), además de características relacionadas con la fisiología de la planta. Hubo competencia entre cultivares de frijol carioca en presencia de Alexandergrass, independientemente de la proporción de plantas, lo que provocó reducciones en el DP, AF, y MS. Básicamente, existe competencia por los mismos recursos ambientales entre el cultivo de frijoles y Alexandergrass.

Abstract The objective of this work was to evaluate the competitive ability of carioca bean cultivars BRS FC104, BRS FC402, IAC Imperador, IAC Milênio, IPR Tangará, and SCS Riqueza in the presence of Alexandergrass (Urochloa plantaginea) in different proportions of plants in association. The experiments were carried out in a greenhouse in a completely randomized design with four replications. The treatments were arranged according to the proportions of beans and Alexandergrass plants: 100:0, 75:25, 50:50, 25:75, and 0:100 or 40:00, 30:10, 20:20, 10:30, and 0:40 plants per pot. The competitiveness of the species was analyzed using diagrams applied to replacement experiments and also through relative competitiveness indices. At 30 days after crop emergence, leaf area (LA), height (HP), diameter (DP), and shoot dry mass (SM) of the plant shoots were measured, as well as variables related to the physiology of the species. There was competition among carioca bean cultivars in the presence of Alexandergrass regardless of the proportion of plants, causing decreases in DP, LA and SM. Basically, there is competition for the same environmental resources between beans and Alexandergrass.

RESUMEN Entre las malezas que interfieren en el crecimiento y desarrollo del sorgo dulce se destaca el amor seco, especialmente por presentar alta capacidad competitiva por los recursos disponibles en el medio. El objetivo de este estudio es comparar la capacidad competitiva del sorgo dulce (Sorghum bicolor) frente al papunga (Bidens pilosa), en función de la proporción de cultivo y planta. Los experimentos se realizaron en un invernadero en un diseño completamente al azar, con cuatro repeticiones. Los tratamientos se organizaron en series de reemplazo en las proporciones de 100: 0, 75:25, 50:50, 25:75 y 0: 100% (sorgo: maleza) que correspondieron a 20:0, 15:5, 10:10, 5:15 y 0:20 plantas por maceta con volumen de 8 dm3 de sorgo dulce (cultivares BRS 506, BRS 509 o BRS 511) contra B. pilosa. Cincuenta días después de la emergencia, se evaluaron el área foliar de la planta (LA), la masa seca de los brotes (MS), la fotosíntesis (A) y la transpiración (E). La capacidad competitiva se analizó utilizando el método de análisis gráfico, construyendo diagramas basados en la productividad total y relativa. También se determinaron la competitividad, el coeficiente de agrupamiento y la agresividad. Los cultivares de sorgo, en general, fueron menos competitivos en todas las proporciones de B. pilosa. Hubo pequeñas diferencias en la capacidad competitiva entre los cultivares de sorgo; BRS 509 demostró ser ligeramente más competitivo que BRS 506 y BRS 511 frente al B. pilosa a. Sin embargo, es poco probable que esto proporcione una ventaja competitiva para BRS 509 en los campos de producción, por lo que B. pilosa a debe controlarse de manera eficiente al principio del ciclo de cultivo para evitar pérdidas de productividad, independientemente del cultivar de sorgo.

ABSTRACT Among the weeds that interfere with the growth and development of sweet sorghum, beggar ticks stands out, because it has a high competitive capacity for the available resources. This study aims to compare the competitive ability of sweet sorghum (Sorghum bicolor (L.) Moench) against hairy beggarticks (Bidens pilosa L.), as a function of cultivar and plant proportion. Experiments were conducted in a greenhouse in a completely randomized design with four replications and six treatments. Treatments were arranged in replacement series in the proportions of 100:0, 75:25, 50:50, 25:75, and 0:100% (sorghum:weed) equivalent to 20:0, 15:5, 10:10, 5:15 and 0:20 plants per pot with 8 dm3 capacity of sweet sorghum (cultivars ‘BRS 506’, ‘BRS 509’ or ‘BRS 511’) against hairy beggarticks. Fifty days after emergence, plant leaf area (LA), aboveground dry mass (DM), photosynthesis (A), and transpiration rates (E) were measured. Competitive ability was analyzed by using the graphical analysis method and building diagrams based on total and relative productivity. Competitiveness, clustering coefficient, and aggressiveness were also determined. Sorghum cultivars, in general, showed losses independently of the proportion of hairy beggarticks. Statistical analysis showed small differences in competitive ability among sorghum cultivars; ‘BRS 509’ was also demonstrated to be slightly more competitive than ‘BRS 506’ and ‘BRS 511’ against hairy beggarticks. This, however, is unlikely to provide a competitive advantage for ‘BRS 509’ in production fields, and hairy beggarticks should be efficiently controlled early in the crop cycle to avoid productivity losses, independently of the sorghum cultivar.

ABSTRACT Enlist™ technology confers resistance to 2,4-D herbicides, glyphosate, and ammonium glufosinate for soybeans. However, the application of herbicides to plants can generate stress, even in resistant crops. Thus, here we evaluated whether the application of herbicides in transgenic soybean farms, resistant to these herbicides, adversely affects the activity of antioxidant enzymes and porphobilinogen formation by delta-aminolevulinate dehydratase (ALA-D) activity. At seven days after herbicide application, the aerial part of the plants was collected and used to determine the activity of antioxidant enzymes as catalase, ascorbate peroxidase, and guaiacol peroxidase, such as lipid peroxidation levels and the activity of the ALA-D enzyme. At seven days after herbicide application, the aerial part of plants was collect and used to determine the activity of antioxidant enzymes, such as catalase, ascorbate peroxidase and guaiacol peroxidase, as well as the levels of lipid peroxidation and the activity of the ALA-D enzyme. The activity of important antioxidant enzymes involved in the scavenging of reactive oxygen species (ROS) was increased in the soybean cultivar with the Enlist™ technology, while no severe damage to lipids was detected. However, the activity of ALA-D was inhibited, which could potentially impair the formation of porphobilinogen and decrease photosynthetic efficiency. Thus, these results indicate that herbicides can affect the activity of ROS-scavenging enzymes even in transgenic, herbicide-resistant plants.

ABSTRACT The identification of the application stage and correct dose of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide is important so that wheat is not harmed. In view of this, the objective of this study was to evaluate the effect of 2,4-D doses applied at different development stages of wheat crop. The experiment was conducted in a randomized block design, arranged in a 4 × 5 factorial scheme, with four replications. In factor A, the application stages (before tillering, tillering, first node and booting) were allocated and the doses of 2,4-D (0, 349, 698, 1047 and 1396 g.ha–1) were allocated in factor B. The variables evaluated were phytotoxicity at 7, 14, 21, 28 and 35 days after application of the treatments (DAT), photosynthetic activity, CO2 internal concentration, stomatal conductance, efficient water use and carboxylation efficiency. The number of spikes·m–2, spike length and number of full and sterile grains were determined in the preharvest. Thousand grain mass, grain yield and hectoliter weight were determined after harvest. The results demonstrate that the herbicide caused phytotoxicity to wheat, being greater in increasing doses and mainly before tillering, causing grain sterility and decreased productivity. The other yield components did not present difference when increasing the dose and application in different stages as well as the physiological variables. The increase of the 2,4-D doses applied before tillering and in the booting stage caused linear decrease in wheat grain yield.

Resumen El objetivo de este estudio fue evaluar la capacidad competitiva de los híbridos de canola (Brassica napus var. oleifera) en competencia con la avena negra (Avena strigosa), en un ambiente subtropical. Los experimentos se llevaron a cabo en un invernadero donde los híbridos de canola Hyola 61, Hyola 76, Hyola 433 y Hyola 571 fueron probadas individualmente por su habilidad competitiva contra la avena negra. Se cambió la proporción de plantas (100%: 0%; 75%: 25%; 50%: 50%; 25%: 75% y 0%: 100%) manteniendo constante la población total de plantas (20 plantas parcela -1). Se evaluaron el área foliar (AF: m2 m-2) y la materia seca (DM: g m-2) además de la tasa de fotosíntesis (A: μmol m-2 s-1), la concentración interna de CO2 (Ci: μmol mol-1) y la tasa de transpiración (E: mol H2O m-2 s-1) se evaluaron utilizando un analizador de gases en el infrarrojo (IRGA) 55 días después de la emergencia. Se registró una intensa competencia entre la canola y la avena negra. La capacidad competitiva de los híbridos de canola fue distinta; Hyola 571 se desempeñó mejor que los otros, siendo una opción para mantener altos niveles de rendimiento en condiciones competitivas con avena negra. Elegir híbridos más competitivos como el Hyola 571 ayuda a mantener altos niveles de rendimiento de canola en áreas infestadas con avena negra.

Abstract The objective of this study was to assess the competitive ability of canola (Brassica napus var. oleifera) hybrids in competition with black oat (Avena strigosa) in a subtropical environment. The experiments were conducted in a greenhouse where canola hybrids ‘Hyola 61,’ ‘Hyola 76,’ ‘Hyola 433,’ and ‘Hyola 571’ were tested individually for their competitive performance with black oat. The plant proportion between black oat and the canola hybrid was changed (100%:0%; 75%:25%; 50%:50%; 25%:75%; and 0%:100%) while keeping the total population of plants constant (20 plants plot-1). Photosynthesis rate (μmol m-2 s-1), internal CO2 concentration (μmol mol-1), and transpiration rate (mol H2O m-2 s-1) were assessed using an infrared gas analyzer 55 days after emergence. Leaf area (m2 m-2) and dry matter (g m-2) were also assessed on the same day. The data set was analyzed by the replacement series method for competition studies. There was evidence of intense competition between canola and black oat, independent of plant proportion. The competitive ability of canola was distinct among hybrids; Hyola 571 performed better than the others in the competition against black oat. Choosing the most competitive hybrid, such as Hyola 571, helps maintain high canola grain yield levels in areas infested with black oat.

RESUMO O milho é um dos principais cereais cultivados no mundo e o leiteiro aparece entre as plantas daninhas que causam prejuízos na produção de grãos. Objetivou-se com o trabalho avaliar a habilidade competitiva relativa de híbridos de milho na presença de um biótipo de leiteiro, por meio de experimentos em série de substituição. Em experimentos preliminares, determinou-se a população de plantas em que a massa seca se torna constante. Tanto para os híbridos de milho Agroeste, Morgan, Nidera e Velox, quanto para o leiteiro, a população foi de 20 indivíduos vaso-1. Posteriormente foram instalados experimentos conduzidos em série de substituição, nas diferentes combinações das espécies, variando-se as proporções relativas (100:0, 75:25, 50:50, 25:75 e 0:100%). A análise da competitividade das espécies foi efetuada por meio de diagramas aplicados a experimentos substitutivos e pelos índices de competitividade relativa. A estatura (EP), índice de clorofila (IC), área foliar (AF) e a massa seca da parte aérea (MS) das plantas foram avaliadas aos 50 dias após a emergência. Ocorre competição entre os híbridos de milho com o leiteiro, sendo ambos afetados negativamente, independentemente da proporção de plantas, provocando reduções nas EP, IC, AF e MS das espécies. A competição entre o milho e leiteiro ocorre basicamente pelos mesmos recursos do meio. A competição interespecífica ocasiona maiores prejuízos ao milho e o leiteiro do que a competição intraespecífica. De modo geral observou-se que apenas os híbridos Nidera e Velox foram mais competitivos do que o leiteiro.

ABSTRACT Maize is one of the main cereals cultivated worldwide and wild poinsettia is among the weeds that cause damage in grain production. The objective of this study was to evaluate the relative competitive ability of maize hybrids in the presence of a wild poinsettia biotype through experiments in replacement series. In preliminary experiments, it was determined the plant population in which the dry mass becomes constant. For the maize hybrids ‘Agroeste’, ‘Morgan’, ‘Nidera’, and ‘Velox’, as well as the wild poinsettia, the population was 20 individuals vase-1. Subsequently, experiments were carried out in replacement series in different combinations of species that varied the relative proportions (100:0, 75:25, 50:50, 25:75, and 0:100%). The analysis of the species' competitiveness was carried out using diagrams applied to the replacement experiments and by the relative competitiveness indexes. The height (PH), chlorophyll index (CI), leaf area (LA), and the shoot dry mass (DM) of the plants were evaluated 50 days after emergence. There was competition between the maize hybrids and the wild poinsettia; both were negatively affected, regardless of the proportion of plants, causing reductions in the species' PH, CI, LA, and DM. The competition between maize and wild poinsettia occurs for the same resources in the environment, and interspecific competition caused greater damage to maize and wild poinsettia than intraspecific competition. In general, it was observed that only the hybrids ‘Nidera’ and ‘Velox’ were more competitive than the wild poinsettia.

Abstract Background Weeds compete with crops, demanding efficient control to avoid yield losses. Highly competitive cultivars are a cultural method that can increase weed suppression and reduce the effects of crop-weed competition. Objective The present study aimed to assess the competitive abilities of barley cultivars (crop) against black oat (weed) and their interference in crop physiology. Methods A preliminary additive experiment was carried out with increasing densities of barley and black oat to determine the minimal density from where there was no drier mass increasing per area. In the second experiment, a replacement series experiment, five plant proportions (100:0; 75:25; 50:50; 25:75, and 0:100) of the crop were used and the competitor was installed. Fifty days after the emergence, morphophysiological and physiological variables, as well as their respective relative competitiveness indexes, relative clustering coefficient, and species aggressiveness, were all assessed. Results The variables associated with the photosynthesis were dependent on the cultivar. BRS Cauê was the cultivar that performed better against black oat, with an increase in the overall photosynthetic rate, due to a smaller leaf area loss, as the competition increased. BRS Brau reduced the photosynthesis into smaller proportions for the competitor. The water use was not impacted to the same extent as photosynthesis. Conclusions BRS Cauê was the most competitive cultivar, suffering the lowest impact of competition with black oat.

RESUMO: O Brasil se destaca na produção de soja, sendo o maior exportador e o segundo maior produtor do grão e a maior parte é cultivado em sistema plantio direto (SPD). Objetivou-se avaliar o efeito da compactação, cultivo e quantidades de palha de aveia preta na superfície do solo sobre o crescimento e o rendimento de grãos de soja em SPD em terras baixas. O delineamento experimental foi inteiramente casualizado com sete tratamentos e quatro repetições. Os tratamentos, nas safras 2016/17 e 2017/18, foram: 1) Pousio no inverno sem compactação (WF); 2) Pousio no inverno + compactação (WF-C); 3) Aveia preta e retirada da palha superficial + compactação (0R-C); 4) Aveia e retirada da metade da palha + compactação (0,5R-C); 5) Aveia + permanência da palhada + compactação (1R-C); 6) Aveia + a palha retirada do tratamento 3 (2 doses palha) + compactação (2R-C); 7) Aveia + permanência da palha, sem compactação (1R). No estádio fenológico R2 a soja foram avaliadas a massa seca de nódulos e de raízes, massa seca e nitrogênio da parte aérea, altura de plantas e produtividade de grãos. No solo foram avaliadas propriedades físicas nas camadas de 0,0-0,05; 0,10-0,15 e 0,20-0,25 m. A produção de massa seca da parte aérea de soja é > 38% em solo não compactado em ano com excesso hídrico independente da quantidade de palha de aveia na superfície. Em ano com pequeno déficit hídrico os tratamentos com mais palha produziram > 5% de massa seca da parte aérea e > 4% de grãos de soja, independente da compactação. O crescimento e o rendimento de grãos de soja em terras baixas oscilam de acordo com as condições hídricas, sendo influenciada pela compactação e quantidade de palha superficial.

ABSTRACT: Brazil is the largest exporter and second largest producer of soybean grains. Most of this production is from plants grown under no-tillage system (NT). This research evaluated the effect of soil compaction, and different amounts of black oat residues on the soil surface on soybean growth and grain yield in lowland under NT. The experiment was conducted in a completely randomized design with seven treatments and four replications, in the 2016/2017 and 2017/2018 crop seasons. The treatments consisted of: 1) winter fallow without soil compaction (WF); 2) winter fallow with soil compaction (WF-C); 3) black oats and complete removal of surface residues, with soil compaction (0R-C); 4) black oats and removal half of surface residues, with soil compaction (0.5R-C); 5) black oats without surface residue removal, with soil compaction (1R-C); 6) black oats without surface residue removal, plus the residues from treatment 3, with soil compaction (2R-C); 7) black oats without surface residue removal, without soil compaction (1R). When the soybean plants were at the phenological stage R2, they were evaluated nodule, root and shoot dry matter, nitrogen contents, plant height, and grain yield. The soil physical properties were evaluated in the 0.0-0.05, 0.10-0.15 and 0.20-0.25 m layers. The soybean aerial dry matter is > 38% in non-compacted soil in year with soil water excess, regardless of the amount of surface oat straw. In year with small water deficit, soil with more surface oat straw produced > 5% shoot dry matter and > 4% of soybean grain, regardless of compaction. The plant growth and grain yield soybean in lowland varied according to the water conditions, and were affected by soil compaction and amounts of black oats residues on soil surface.

Resumo O objetivo deste trabalho foi avaliar os efeitos de doses de metsulfurom-metílico, aplicadas em diferentes épocas, sobre as características fisiológicas e produtivas da soja (Glycine max), em dois anos agrícolas, em condições de campo, tendo-se utilizado o pepino (Cucumis sativus) como planta bioindicadora, em casa de vegetação. Os experimentos foram conduzidos em blocos ao acaso, em arranjo fatorial 4x5, com quatro repetições. O fator A foi o tempo de aplicação do herbicida (45, 30, 15 e 0 dias antes da semeadura da soja, DAS), e o fator B foi a dose de metsulfurom-metílico (0, 3,6, 5,4, 7,2 e 9,0 g ha-1 i.a.). Foram avaliadas as seguintes variáveis: fitotoxicidade, trocas gasosas, fluorescência da clorofila a e componentes de rendimento. A maior fitotoxicidade em plantas de soja é observada após o uso da maior dose de metsulfurom-metílico e com semeadura em 0 DAS. A taxa de transporte de elétrons reduz drasticamente com o aumento da dose de metsulfurom-metílico e da proximidade da semeadura, enquanto a extinção não fotoquímica, como mecanismo de defesa, aumenta em plantas de soja expostas ao transporte de herbicida de até 5,4 g ha-1. Os resíduos de metsulfurom-metílico reduzem o peso de mil grãos e a produtividade de soja em função da dose de aplicação e do período de semeadura. Para as plantas de pepino, também foram verificados efeitos negativos nas características fisiológicas. Um intervalo de mais de 45 dias é recomendado para a semeadura da soja após a aplicação de metsulfurom-metílico para dessecação.

Abstract The objective of this work was to evaluate the effects of metsulfuron-methyl rates, applied at different times, on the physiological and productive traits of soybean (Glycine max) in two crop years, in field conditions, using cucumber (Cucumis sativus) as a bioindicator plant, in greenhouse conditions. The experiments were conducted in a randomized complete block, in a 4x5 factorial arrangement, with four replicates. Factor A was the herbicide application time (45, 30, 15, and 0 days before soybean sowing, DBS), and factor B was the metsulfuron-methyl rate (0, 3.6, 5.4, 7.2, and 9.0 g ha-1 a.i.). The following variables were evaluated: phytotoxicity, gas exchange, chlorophyll a fluorescence, and yield components. The highest phytotoxicity in soybean plants is observed after the use of the highest rate of metsulfuron-methyl and with sowing at 0 DBS. The electron transport rate drastically reduces with an increasing metsulfuron-methyl rate and sowing proximity, whereas non-photochemical quenching, acting as a defense mechanism, increases in soybean plants exposed to a herbicide carryover of up to 5.4 g ha-1. Metsulfuron-methyl carryover reduces soybean 1,000-grain weight and productivity as a function of application rate and sowing period. For the cucumber plants, negative effects on physiological traits were also verified. An interval of more than 45 days is recommended for sowing soybean after metsulfuron-methyl application for desiccation.

Resumen El objetivo de esta investigación fue evaluar los daños inmediatos y latentes por temperatura de secado en la calidad física y fisiológica de las semillas de avena negra. Las semillas se secaron en un horno con circulación de aire a temperaturas de 30, 40 y 50°C, además del uso de temperaturas alternas (40-50°C). Después del secado, las semillas se almacenaron en condiciones ambientales durante 180 días, y los análisis físicos y fisiológicos se realizaron cada 45 días. Se observó que la calidad física de las semillas de avena negra se redujo con un aumento en el tiempo de almacenamiento, independientemente de la temperatura de secado utilizada. La calidad fisiológica de las semillas de avena negra aumentó durante el almacenamiento hasta que se superó la latencia, independientemente de la temperatura de secado. La elevación de la temperatura de secado causa daños inmediatos en la calidad física de las semillas de avena negra, mientras que la calidad fisiológica tiende a sufrir la influencia negativa del aumento de la temperatura del aire de secado de forma latente.

Abstract The objective of this research was to evaluate the immediate and latent drying temperature damages on the physical and physiological quality of black oat seeds. The seeds were dried in an oven with air circulation at temperatures of 30, 40 and 50°C, in addition to the use of alternating temperatures (40-50°C). After drying the seeds were stored under environmental conditions for 180 days, and physical and physiological analyses were performed every 45 days. It was observed that the physical quality of black oat seeds was reduced with an increase in the storage time, regardless of the drying temperature used. The physiological quality of black oat seeds increased throughout storage until dormancy was overcome, regardless of the drying temperature. Elevated drying temperatures cause immediate damages to the physical quality of black oat seeds, whereas physiological quality tends latently to suffer the negative influence of increasing the temperature of the drying air.

RESUMO O uso de glifosato associado com outros herbicidas torna-se uma alternativa importante para o manejo de plantas daninhas infestantes do milho, pois ele aumenta o espectro de controle, minimiza problemas com resistência e tolerância de plantas daninhas ao herbicida. O objetivo deste trabalho foi estudar a eficiência, a seletividade e os efeitos nos componentes de rendimento de grãos do milho resistente ao glifosato pelo uso dessa substância associada ou não a outros herbicidas aplicados em pré- e pós-emergência. O experimento foi instalado em delineamento de blocos ao acaso, com quatros repetições. Os tratamentos consistiram na utilização do glifosato em combinação com os herbicidas: atrazina, [atrazina + simazina], [atrazina + óleo], [atrazina + S-metolacloro], aplicados em pré- e/ou pós-emergência e o [nicosulfuron + mesotriona] somente em pós-emergência, além das testemunhas capinada e infestada. Avaliaram-se as variáveis: fitotoxicidade ao milho, controle de plantas daninhas, altura de inserção de espigas, número de fileiras e de grãos por espiga, peso de mil grãos e a produtividade de grãos. Os herbicidas ocasionaram baixa fitotoxicidade ao milho, inferior a 6%, controle superior a 88, 95 e 95% para papuã, nabo e girassol, respectivamente, e não influenciaram negativamente nos componentes relacionados ao rendimento de grãos da cultura. Os herbicidas testados são seletivos ao híbrido Forseed 2A521 PW e efetivos no controle de papuã, nabo e girassol. O manejo das plantas daninhas com capina ou herbicidas proporcionou aumento de cerca de 43% na produtividade de grãos do híbrido de milho Forseed 2A521 PW. O uso de glifosato em mistura de tanque com herbicidas aplicados em pré- ou pós-emergência incrementou, aproximadamente, 14% a produtividade de grãos de milho.

ABSTRACT The application of glyphosate associated with other herbicides is an important alternative for weed control in maize, to increase control spectrum and to minimize problems with resistance and tolerance from some species to the product. The objective of this work was to evaluate the efficacy, selectivity and effects on the grain yield components of glyphosate-resistant maize as a function of its application, associated or not with other pre- and postemergence herbicides. The design used was randomized blocks with four replications. Treatments consisted in the use of glyphosate combined with the herbicides: atrazine, [atrazine + simazine], [atrazine + oil], [atrazine + S-metolachlor], applied pre- and/or postemergence and [nicosulfuron + mesotrione] only postemergence, plus two controls, one weeded and one infested. The evaluated variables were maize phytotoxicity, weed control, ear insertion height, number of rows per ear, number of grains per row, one thousand grain mass and grain yield. Herbicide treatments caused low phytotoxicity to maize, less than 6%; control greater than 88, 95 and 95% for alexandergrass, turnip and sunflower, respectively, and did not affect grain yield components. The tested herbicides are selective to the hybrid Forseed 2A521 PW and effective in weed control. Weed control with weeding or herbicide increased maize Forseed 2A521 PW yield by 43%. The association of glyphosate with pre- or postemergence herbicides increased maize grain yield by approximately 14%.

Avaliou-se com este trabalho, o efeito dos compostos voláteis dos óleos essenciais de alho (Allium sativum), arruda (Ruta graveolens), carqueja (Baccharis trimera) e nim (Azadirachta indica) sobre o crescimento miceliar e esporulação de Monilinia fructicola. O fungo foi isolado em meio de cultura BDA (Batata-Dextrose-Ágar) a partir de pêssegos infectados pelo patogénio. Foi aplicado a dose de 20 μL de cada óleo essencial em papel de filtro esterilizado com 1,5 cm², já fixado com cola quente no centro da tampa da caixa de Petri®. Colocou-se um disco contendo micélio e conídios do patogénio de 0,5 cm de diâmetro no centro da superfície do meio de cultura BDA. Todas as caixas foram vedadas com parafilm e em seguida, incubadas em BOD a 25 ºC e fotoperíodo de 12 h. Após 24 h iniciou-se a medição do crescimento miceliar de M. fructicola, por 7 dias, neste dia foi avaliada a produção de conídios. O óleo essencial de alho libertou compostos voláteis que inibiram totalmente o crescimento miceliar de M. fructicola, o que pode ser observado também na produção de conídios. Os demais óleos não diferiram da testemunha.

The effect of the volatile compounds of the essential oils of garlic (Allium sativum), rue (Ruta graveolens), carqueja (Baccharis trimera) and neem (Azadirachta indica) on mycelial growth and sporulation of Monilinia fructicola were evaluated. The fungus was isolated in BDA (Potato-Dextrose-Agar) culture medium from peaches infected by the pathogen. The 20 mL dose of each essential oil was applied on 1,5 cm² already fixed with hot glue in the center of the Petri dish lid. A disk containing mycelium and conidia of the 0,5 cm diameter pathogen containing mycelium and conidia of the pathogen was placed in the center of the surface of the BDA culture medium. All boxes were sealed with parafilm and then incubated in BOD at 25 ° C and photoperiod for 12 h. After 24 h the measurement of mycelial growth of M. fructicola was started for 7 days, on this day the production of conidia was evaluated. Garlic essential oil released volatile compounds that totally inhibited M. fructicola mycelial growth, which can also be observed in the production of conidia. The other oils did not differ from the control.