ABSTRACT Second-generation glyphosate-tolerant maize (Roundup Ready 2, RR2) is characterised by the expression of the cp4epsps gene. Despite some studies suggesting possible undesirable effects from the application of glyphosate in RR2 maize, other reports have demonstrated glyphosate selectivity for RR2 plants, with minor damage symptoms, if any, and with no negative effects on the chlorophyll indices. The aim of this study was to evaluate the effect of different types of glyphosate management, formulations and rates of application on chlorophyll indices and the agronomic performance of an RR2 maize genotype expressing the cp4epsps gene. Five experiments were conducted in a full factorial design (2 x 5 x 5) to evaluate two types of management, two formulations and five rates of glyphosate. Damage symptoms, chlorophyll indices and variables related to agronomic performance (plant height, stem diameter, yield and 100-grain weight) were evaluated. Similar crop responses were found for each of the glyphosate formulations (potassium salt and isopropylamine salt) and types of management (single application and sequential application) under test, indicating that the use of glyphosate-based commercial products affords flexibility in terms of formulation and frequency of application. Glyphosate formulated as potassium salt or isopropylamine salt and applied to RR2 maize either in a single application (full rate) or in two sequential applications (each at half rate) has a similar effect and may therefore be used without distinction. However, it is important to consider the rate of application since high rates of glyphosate (especially greater than 1,440 g ae ha-1) may affect the development and production of RR2 maize.

ABSTRACT Glyphosate, glufosinate, and atrazine do not affect the growth and development of glyphosate and glufosinate-tolerant (RR2/ LL) maize; however, the results are less consolidated for these herbicides applied in mixtures. The aim of the present study was to evaluate the effects of post-emergent application of glyphosate, glufosinate, and atrazine, alone and in mixtures, on the growth and development of the RR2/LL maize. The treatments consisted of the application of glyphosate (1080 g of acid equivalent [ae] ha-1), glufosinate (500 g of active ingredient [ai] ha-1), atrazine (2000 g [ai] ha-1), glyphosate + glufosinate, glyphosate + atrazine, glufosinate + atrazine, glyphosate + glufosinate + atrazine, and the control (without application). The experiment was carried out in two locations under greenhouse conditions with different maize hybrids. Crop injury and variables of the agronomic performance (height, stem diameter, chlorophyll indexes, fresh and dry weight of shoot, root dry weight, and total dry weight) were evaluated. Herbicides applied alone or in binary mixtures did not cause major damage. However, the application of the three associated herbicides in some situations might result in detrimental effects on the development of the RR2/LL maize.

RESUMEN Glifosato, glufosinato y atrazina no afectan el crecimiento y desarrollo de las plantas de maíz tolerantes a glifosato y a glufosinato (RR2/LL); sin embargo, los resultados están menos consolidados para estos herbicidas aplicados en mezclas. El objetivo del presente estudio fue evaluar los efectos de la aplicación post-emergente de glifosato, glufosinato y atrazina, solos y en mezclas, sobre el crecimiento y desarrollo del maíz RR2/LL. Los tratamientos se formaron por aplicación de gli-fosato (1080 g de ácido equivalente [ae] ha-1), glufosinato (500 g de ingrediente activo [ia] ha-1), atrazina (2000 g [ai] ha-1), glifosato + glufosinato, glifosato + atrazina, glufosinato + atrazina, glifosato + glufosinato + atrazina, además del testigo (sin aplicación). El experimento se llevó a cabo en dos localidades, en condiciones de invernadero, con diferentes híbridos de maíz. Se evaluó la fitotoxicidad al cultivo y variables relacionadas con el crecimiento del mismo (altura, diámetro del tallo, índices de clorofila, masa fresca y seca de la parte aérea, masa seca de las raíces, masa seca total). Los herbicidas aplicados solos o en mezclas binarias, no causaron danos importantes. Sin embargo, la aplicación de los tres herbicidas en asociación en algunas situaciones puede resultar en efectos perjudiciales sobre el desarrollo del maíz RR2/LL.

A utilização de altas doses de glyphosate, mesmo na tecnologia tolerante (RR) pode causar injúrias nas plantas, conhecido como efeito “Yellow flashing”, que é caracterizado por um amarelecimento das folhas apicais, podendo levar à perda de produtividade. O presente estudo objetivou avaliar técnicas visando a atenuação do efeito de doses de glyphosate em cultivares tolerantes de soja (RR e RR2). Os ensaios foram conduzidos em estufa nos anos 2015/2016 e 2016/2017, em Palotina, região oeste do Paraná em um arranjo inteiramente casualizado. O primeiro ensaio foi conduzido em arranjo fatorial 3x8 (produtos x cultivares) com quatro repetições utilizando misturas de glyphosate com regulador de crescimento, um composto de aminoácidos e uma fonte de manganês, e no segundo um esquema fatorial 6x3 (produtos x cultivares) utilizando glyphosate, um regulador de crescimento, uma fonte de manganês isolados e o glyphosate associado aos demais produtos, além de um tratamento controle sem aplicação. Foram avaliados visualmente a fitotoxicidade, índice de clorofila, massa seca de parte aérea e de raiz. Observou-se uma diferença de resposta para as cultivares devido a características de cada genótipo. Não foram observadas diferenças entre os produtos. A cultivar ‘M6210’ apresentou-se maior sintoma de fitointoxicação enquanto a cultivar ‘BMX Ponta’ apresentou maior tolerância. Para o segundo ensaio não foi observado efeito fitotóxico.

The use of high rates of glyphosate, even if tolerant (RR) technology, can cause leaf insults, such as the yellow flashing effect, which is characterized by a yellowing of the leaves, which can lead to loss of yield. The present study aimed to increase doses of glyphosate in tolerant soybean. Tests were conducted in greenhouse 2015/2016 and 2016/2017, in Palotina, western region of Paraná in a completely randomized arrangement. The first assay was conducted in a 3x8 factorial set (products x cultivars) with four replicates mixed with glyphosate with growth regulator, one compound of amino acids and one source of manganese, and in the second a factorial scheme 6x3 (products x cultivars) using glyphosate, a growth regulator, a source of manganese and the glyphosate associated to the other products, besides a control without application. A phytotoxicity, chlorophyll index, shoot dry mass and root mass were evaluated visually. A variation of response to cultivar was observed due to characteristics of each genotype. The differences between the products were not observed. A cultivar ‘M6210’ presented greater symptom of crop injury while cultivating ‘BMX Ponta’, presenting greater tolerance. No phytotoxic effect was observed for the test.

O objetivo do trabalho foi avaliar a influência do arranjo espacial, via redução de espaçamento entre linhas de plantas, na cultura do milho em dois solos de baixa altitude no Oeste do Estado do Paraná, Brasil. Os trabalhos foram conduzidos em duas áreas experimentais da Cooperativa C.Vale, no ano agrícola de 2014/15, uma situada em Palotina (solo muito argiloso) e a outra em Brasilândia do Sul (textura média), em que o delineamento experimental foi o de blocos casualisados, com quatro repetições. Os tratamentos foram dispostos em modo fatorial duplo 2x4 (Híbridos X Espaçamentos) e os híbridos de milho utilizados foram o 2B587PW e o 2B810PW. Os espaçamentos entre as linhas foram de 25, 50, 75 e 100 cm. Os híbridos de milho foram semeados e mantidos com uma população de 70 mil plantas por hectare. As variáveis analisadas foram: altura de plantas e diâmetro do colmo; número de plantas acamadas; número de espigas danificadas; número de espigas expostas; percentagem de grãos ardidos; massa de 100 grãos e produtividade. A melhor disposição de plantas nos solos de baixa altitude, foi conferida pela redução do espaçamento entre as linhas e o aumento do espaçamento entre plantas na linha.

The aim of this work was to evaluate the influence of the spatial arrangement, by reducing spacing between plant lines, on maize cultivation in two low altitude soils in the western part of the State of Paraná, Brazil. The studies were conducted in two experimental areas of Cooperativa C.Vale, in the agricultural year of 2014/15, one located in Palotina (very clayey soil) and the other in South Brasilândia (medium texture), in which the experimental design was the randomized blocks with four replicates. The treatments were arranged in a 2x4 double factorial (Hybrids X Spacings) and the corn hybrids used were 2B587PW and 2B810PW. The lines spacing were 25, 50, 75 and 100 cm. Corn hybrids were sown and maintained with a population of 70 thousand plants per hectare. The analyzed variables were: height of plants and diameter of stems; number of bedded plants; number of damaged spikes; number of exposed spikes; percentage of burned grains; mass of 100 grains and productivity. The best arrangement of plants in soils at low altitude was conferred by the reduction of line spacing and the increase of plant spacing in the line.

ABSTRACT Eucalyptus stands out in the Brazilian silvicultural sector as the most planted tree species for commercial purposes thus, practices that facilitate management and improve wood quality are increasingly required. Although artificial mechanical pruning has been used for this crop, the use of herbicides for pruning can be more practical, rapid and have lower costs. Thus, the objective of this work was to evaluate the use of glufosinate ammonium in the chemical pruning of eucalyptus plants. Eucalyptus seedlings were transplanted into 10-L pots filled with soil and substrate and subjected to the treatments (mechanical pruning, chemical pruning, and no pruning) 90 days after transplanting. Lateral branches were cut with pruning shears for the mechanical pruning. Glufosinate ammonium (500 g a.i. ha-1) was applied to the sides of the plants for the chemical pruning, simulating a field-planting row (3.5 x 2.0 meters), using a CO2-pressurized sprayer; the untreated branches were covered with plastic bags to avoid receiving the herbicide. The percentage of artificial pruning used was 60% of the vertical height of the eucalyptus plants. Glufosinate, glutamate, and ammonia contents, electron transport rate, percentage of pruning, plant height, number of leaves, and dry matter mass of the plants were evaluated. The application of glufosinate ammonium defoliate the treated branches and did not affect significantly the parts of the plants that did not receive the herbicide regarding the evaluated compounds, and growth of the plants, denoting that glufosinate ammonium can be used for chemical pruning of eucalyptus plants.

Resumo: O objetivo deste trabalho foi avaliar o efeito de espécies de cobertura de inverno no desempenho agronômico de soja cultivada em sucessão, sob plantio direto. O trabalho foi realizado durante três safras (2011/2012, 2012/2013 e 2013/2014), com os seguintes cultivos de cobertura: aveia-branca (Avena sativa), aveia-preta (Avena strigosa), azevém (Lolium multiflorum), ervilhaca (Vicia sativa), nabo-forrageiro (Raphanus sativus), consórcio de aveia-preta + nabo-forrageiro e trigo (Triticum aestivum) como manejo-padrão. O nabo-forrageiro e o consórcio aveia-preta + nabo-forrageiro proporcionaram maiores percentagens de cobertura do solo após 30 dias do plantio, bem como produção de matéria seca nas três safras. Após 45 e 90 dias da dessecação, no entanto, a aveia-branca e o azevém apresentaram a maior taxa de cobertura do solo. A aveia-preta e o consórcio aveia-preta + nabo-forrageiro proporcionaram maior produtividade de soja que o manejo-padrão com trigo, nas safras de 2012/2013 e 2013/2014. As espécies de cobertura do solo afetam significativamente a produção de soja cultivada em sucessão, com destaque para a aveia-preta e o consórcio aveia-preta + nabo-forrageiro.

Abstract: The objective of this work was to evaluate the effect of winter cover crop species on the agronomic performance of soybean (Glycine max) cropped in succession, under a no-tillage system. The study was conducted during three crop seasons (2011/2012, 2012/2013, and 2013/2014), with the following cover crops: white oat (Avena sativa), black oat (Avena strigosa), ryegrass (Lolium multiflorum), vetch (Vicia sativa), forage radish (Raphanus sativus), the intercrop black oat + forage radish, and wheat (Triticum aestivum) as the standard management. Forage radish and the intercrop black oat + forage radish provided greater soil cover rates after 30 days of planting, as well as dry matter production in the three crop seasons. After 45 and 90 days from desiccation, however, white oat and ryegrass showed the highest soil cover rate. Black oat and the intercrop black oat + forage radish provided higher soybean yield than the standard management with wheat, in the 2012/2013 and 2013/2014 crop seasons. Winter cover crops can significantly affect soybean yield in succession, and black oat and the intercrop black oat + forage radish stand out for this purpose.

Resumo: Algumas técnicas de manejo da cultura do trigo, como a dessecação pré-colheita podem afetar a produtividade e a qualidade fisiológica das sementes. O objetivo deste estudo foi avaliar o efeito de diferentes herbicidas dessecantes aplicados na cultura do trigo e seus efeitos sobre a produtividade e a qualidade das sementes. O experimento foi conduzido com a cultivar COODETEC 150 (CD 150), em dois ambientes de produção localizados no Município de Palotina - PR, sob o delineamento experimental de blocos casualisados, constituído de 7 tratamentos (herbicidas na dessecação) com 4 repetições. A dessecação foi realizada quando 50% das plantas apresentavam-se no estádio 80 com as sementes de consistência farinácea ou de massa. As variáveis analisadas foram umidade após a colheita, produtividade de sementes, peso hectolitro, massa de 100 sementes, germinação e vigor. Os herbicidas carfentrazone-ethyl e clethodim reduziram o vigor das sementes produzidas, e o herbicida paraquat reduziu o comprimento de plântulas. Ocorreu redução na massa de 100 sementes para o amônio - glufosinate, clethodim, diquat e carfentrazone-ethyl. O amônio - glufosinate, paraquat, glyphosate, clethodim e diquat reduziram a produtividade. A dessecação de plantas da cultivar CD 150 no estádio 80 não é recomendada, em decorrências dos efeitos negativos dos herbicidas nos parâmetros produtivos e fisiológicos das sementes de trigo.

Abstract: Some desiccation techniques for harvesting wheat may affect seed quality. The objective of this study was to evaluate the effect of different desiccant herbicides applied to the wheat crop and their effects on the production and seed quality. The experiment was conducted with cultivar COODETEC 150 (CD 150) in two sites in Palotina (Paraná state, Brazil) with a randomized block design consisting of 7 treatments (desiccation herbicides) and 4 replications. Desiccation was realized when 50% of the plants were in stage 80 with seeds in powdery or mass consistency. The variables analyzed were percentage of moisture content after harvest, Yield, hectoliter weight, mass of 100 seeds, vigor, germination, fresh mass of seedlings, dry mass of seedlings and root length. The herbicides carfentrazone-ethyl and clethodim were the ones that promoted greatest reduction in vigor. The herbicide paraquat caused reduction in seedling length. There was a reduction in the mass of 100 seeds for glufosinate-ammonium, clethodim, diquat and carfentrazone-ethyl. Glufosinate-ammonium, paraquat, glyphosate, clethodim and diquat caused reduction in yield. Desiccation of Cultivar CD 150 at stage 80 is not recommended, since plant Yield and physiological seed parameters were adversely affected by herbicides.