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Non-uniform blossoming due to uninterrupted irrigation is common in perennial crops such as coffee. It usually leads to uneven ripening of fruits and impairs harvesting efficiency and quality of coffee. The effect of different water deficit periods was evaluated, associating them with the deficit level and development stage of the flower bud, on blossoming concentration in irrigated coffee plantations. We also evaluated the effect of water deficit on growth, productivity, maturation, and physical quality of the bean. Two identical trials were performed on 19-month-old 'Coffea arabica' cultivars ('Catuai Vermelho IAC 144' and 'Bourbon Amarelo J9'), from June 2008 to July 2009. Irrigation was suspended and resumed at different times (seven treatments) at the pre-flowering stage using a randomized block design with four replicates. The cultivars reached different levels of deficit for the same period of suspended irrigation. In 'Catuai', 60% of the flower buds opened after the coffee plants were exposed to water deficit from early or late June to early September. In 'Bourbon', even the longer water deficit period (06/09 to 09/07) did not induce blossoming greater than 20%. Growth was slightly affected during the water withholding period, but not in the subsequent evaluations in October or January. In both cultivars, drought promoted a higher percentage of ripe cherries at harvest than continuous irrigation, regardless of treatment. In conclusion, although blossoming was not a single concentrated event, especially in 'Bourbon', withholding irrigation in the pre-flowering stage contributed to uniform fruit ripening in both Arabica coffee cultivars.

Background: Weed control in the pre-harvest of the coffee crop is essential to enable mechanized coffee harvesting. Objective: Testing the efficacy of pre-emergent herbicides, applied after brush shredder or desiccation operations, on the weed control during the coffee crop’s pre-harvest. Methods: Two separate trials were accomplished in commercial Coffea arabica crops in the Cerrado Mineiro Region. In the first one, oxyfluorfen and sulfentrazone were applied after either brush shredder or burndown operation; in the second, they were tested as a tank mixture with glyphosate. Results: In the first assay, the brush shredder use, associated to the rains that follow, stimulated a sharp weed infestation during the pre-harvest, which was not observed in desiccated plots. A sole application of oxyfluorfen or sulfentrazone, following either brush shedder or desiccation operation, effectively controlled the weeds; however, the sequential applications on burndown areas may be needless. The applied herbicides did not intoxicate the coffee plants nor affect their growth. In the second assay, both herbicide mixtures were highly efficient on the weed control through post-emergence application during the pre-harvest, what was not observed with a sole application of glyphosate. In both experiments, a dry period during winter, associated to the operations to gather fallen coffee fruit, collectively contributed to control weeds. Differently from oxyfluorfen, the residual effect of sulfentrazone was high enough to control weed even in the beginning of the rainy season. Conclusion: Sulfentrazone and oxyfluorfen were effective on the weed control in the pre-harvest of the coffee crop, mainly when applied after brush shedder operations.

The goal of this study was to analyze the response of Arabica coffee cultivars grown under three levels of Bidens pilosa (beggarticks) interference. At 30 days after transplanting (DAT) of 14 Arabica coffee cultivars into 11 L pots, beggarticks was seeded in the pots and soon after emergence, three levels of weed infestation were established: none, low (two plants per pot), and high (five plants per pot). Treatments were arranged in a 14 × 3 factorial scheme under a completely randomized design, with four replicates. Coffee plant growth was evaluated at both weed emergence and blossoming (90 DAT) when the experiment was completed. Regardless beggarticks infestation levels, significant effects of cultivars occurred on almost all the coffee growth variables. Specifically, the Arabica coffee cultivars Arara, Asa Branca, and Bourbon Amarelo exhibited greater values for root, leaf, shoot, and whole plant dry matter when compared with the other cultivars. The Arabica coffee cultivars presented lower leaf area increments, and also lower leaf, shoot, and whole plant dry matter accumulation when grown under either low or high infestation levels (between which there were no statistical differences, p>0.05) in comparison with that under the weed-free treatment. However, there were no significant interactions between Arabica coffee cultivars and weed infestation levels for those crop growth variables. We conclude that all Arabica coffee cultivars tested were equally susceptible to B. pilosa competition in this phase of crop implantation. RESUMO: Objetivou-se neste estudo analisar a resposta de 14 cultivares de café arábica sob três níveis de infestação de Bidens pilosa (picão-preto). Aos 30 dias após o transplantio (DAT) das mudas de 14 cultivares de café arábica para vasos de 11 L, sementes de B. pilosa foram semeadas nos vasos, estabelecendo-se, logo após a emergência, três níveis de infestação: nulo; baixo - duas plantas/vaso; e alto - cinco plantas/vaso. O delineamento utilizado foi inteiramente casualizado com quatro repetições, e os tratamentos, distribuídos em esquema fatorial 14 x 3. O crescimento do cafeeiro foi avaliado no momento tanto da emergência quanto do florescimento da planta daninha, quando o experimento foi encerrado, aos 90 DAT. Independentemente dos níveis de infestação, houve efeito significativo do fator cultivar sobre praticamente todas as variáveis avaliadas relacionadas ao crescimento das mudas de café, destacando-se os cultivares Arara, Asa Branca e Bourbon Amarelo J9, que apresentaram maiores matéria seca de folhas, raiz, parte aérea e de planta inteira, em comparação aos demais cultivares. Independentemente dos cultivares, verificou-se menor incremento de área foliar, matéria seca de folha, matéria seca da parte aérea e matéria seca da planta inteira de café, seja em nível de infestação baixo ou alto, entre os quais não houve diferença, em comparação ao tratamento livre de competição. Todavia, as interações entre cultivares e níveis de infestação para essas variáveis não foram significativas, permitindo concluir que todos os cultivares de café testados foram igualmente sensíveis à competição de B. pilosa na fase de implantação da cultura.

The hormesis effect of 2,4-D, applied at two stages of soybean development, on the physiological components of crop yield, was investigated. Soybean seeds of the cultivar ‘AG 3680 IPRO’ were sown in pots containing 7 L of a substrate and kept in a greenhouse. A randomized complete block design with four replicates was used. Eighteen treatments were tested, arranged in a split-plot scheme. The plots consisted of two stages of herbicide application (V4 and V6), and the split-plots were arranged by nine 2,4-D doses (0, 5, 10, 15, 20, 25, 30, 40, and 50 g ha-1). At the time of harvest, 100 days after sowing, significant interactions between crop development stages and 2,4-D doses were observed for the number of nodes in the main stem (NNMS) and the number of pods per plant (NPP). Both NNMS and NPP were not affected by 2,4-D during V6, but they increased with doses up to 20.2 g ha-1 and 22.5 g ha-1, respectively, during V4 and declined at higher doses according to a quadratic model, thus characterizing hermetic effect. Regardless of the application stage, the number of grains per plant and weight of a thousand grains were reduced as doses increased. However, the grain number and grain mass per plant reached maximum values for doses of 20.3 g ha-1 and 12.9 g ha-1, respectively. It was concluded that 2,4-D causes hormesis effects on the soybean crop ‘AG 3680 IPRO’ pot-grown in greenhouse conditions, regardless of the application stages herein tested. RESUMO: Investigou-se o efeito hormético do 2,4-D, aplicado na soja em dois estádios de desenvolvimento, sobre os componentes fisiológicos de produtividade da cultura. Sementes de soja da variedade ‘AG 3680 IPRO’ foram semeadas em vasos contendo 7 L de substrato, mantidos em casas de vegetação. Foram avaliados 18 tratamentos no delineamento em blocos casualizados, com quatro repetições, dispostos em esquema de parcelas subdivididas. As parcelas foram constituídas por dois estádios de desenvolvimento (V4 e V6), e as subparcelas, por nove doses de 2,4-D (0, 5, 10, 15, 20, 25, 30, 40 e 50 g ha-1). Na colheita, aos 100 dias após a semeadura, verificou-se interação significativa entre estádio e dose de 2,4-D para o número de nós na haste principal (NNHP) e para o número de vagens por planta (NDV). O NNHP e o NDV não foram afetados pelo 2,4-D em V6, mas em V4 eles aumentaram até as doses de 20,2 g ha-1 e 22,5 g ha-1, respectivamente, segundo modelo quadrático, declinando em doses maiores, conferindo o efeito hormético. Independentemente do estádio de aplicação, o número de grãos por vagem e o peso de mil grãos reduziram-se com o aumento da dose. Todavia, o número de grãos e a massa de grãos por planta atingiram valores máximos para as doses de 20,3 g ha-1 e 12,9 g ha-1, respectivamente. Concluiu-se que o 2,4-D promove hormese na cultura da soja ‘AG 3680 IPRO’, cultivada em vasos em casa de vegetação, independentemente dos estádios de aplicação testados.

Objetivou-se neste trabalho avaliar o efeito de diferentes formulações à base de glyphosate sobre a colonização micorrízica e nodulação no cultivar de soja RR TMG 125. Os experimentos foram desenvolvidos em condições de campo, em Latossolo Vermelho-Amarelo, durante os anos agrícolas 2010/2011 e 2011/2012. Os tratamentos constaram da aplicação da dose de 720 g e.a. ha-1 das seguintes formulações de glyphosate: Trop®, Roundup Original®, Roundup Ultra®, Roundup WG®, Roundup Transorb R® e Zapp Qi®, além de duas testemunhas (capinada e não capinada). Utilizou-se o delineamento em blocos casualizados com quatro repetições. A matéria seca da parte aérea, nodulação e produtividade de soja não foram influenciadas pelas diferentes formulações de glyphosate. Para a colonização micorrízica, observou-se efeito positivo da formulação Roundup Original®, em relação à testemunha capinada; no entanto, esse efeito não foi contínuo nos dois anos de experimento. A variável número de nódulos foi mais afetada pelas formulações de glyphosate testadas. The aim of this study was to evaluate the effect of different glyphosate-based formulations on mycorrhizal colonization and nodulation in soybean cultivar RR TMG 125. The experiments were conducted under field conditions in Red-Yellow Latosol, during 2010/2011 and 2011/2012. The formulations Trop®, Roundup Original®, Roundup Ultra®, Roundup WG®, Roundup Transorb R® and ZappQi® were used at a glyphosate dose of 720 g a.e. ha-1. The experiment was arranged in a randomized block design with four replications and two controls (hoed control and non-hoed control). The variables shoot, nodule dry matter, and soybean yield were not influenced by the different formulations of glyphosate. For mycorrhizal colonization, it was verified that a positive effect of the herbicide Roundup Original® regarding the hoed control was not continuous in the two years of the experiment. The variable number of nodules was the most affected by the glyphosate formulations tested.

In earlier-maturing coffee clones, owing to the shorter time required for fruit filling and ripening, photo- assimilates should be transported to fruits in a period shorter than that found in intermediate- or late-maturing clones. We hypothesised that at a given source-to-sink ratio, a presumably greater sink strength in early-maturing clones relative to intermediate- and late-maturing individ- uals should be correlated to increased rate of net carbon assimilation (A) and greater photo-assimilate transport to the fruits. Overall, earlier-maturing clones displayed greater A rates than the intermediate-maturing clones, which, in turn, had higher A than their late counterparts. Changes in A were largely associated with changes in stomatal conductance. Only marginal alterations occurred in the internal-to-ambient CO2 concentration ratio, the carbon isotope composition ratio, soluble sugars and chlorophyll a fluorescence parameters. Some changes in starch pools were detected among treatments. To the best of our knowledge, this is the first report showing evidence that increased precociousness of fruit growth and matura- tion results in higher A and thus increased source strength, a fact associated to a large degree with higher stomatal aperture.

RESUMO Objetivou-se com este trabalho avaliar a interação entre o tamanho do vaso de cultivo e doses de glyphosate no crescimento, na fisiologia e na eficácia de controle de Brachiaria decumbens. A semeadura foi feita em vasos contendo 2, 5, 10 e 20 L de substrato, mantidos em casa de vegetação. Entre os 41 e 63 dias após a emergência (DAE), avaliou-se o crescimento deB. decumbens. Aos 64 DAE, fez-se a aplicação do glyphosate nas doses de 0,0, 0,8, 1,6 e 3,2 kg ha-1 de equivalente ácido. Foram avaliadas as trocas gasosas e a fluorescência da clorofila a, aos dois dias após a aplicação (DAA), bem como a eficácia de controle, aos 7, 14, 21 e 28 DAA, sendo nesta última avaliação determinada ainda a matéria seca da parte aérea. Por fim, aferiu-se ainda a capacidade de rebrota de B. decunbens aos 28 dias após o corte. O crescimento de B. decumbens aumentou linearmente com o aumento do tamanho do vaso. As trocas gasosas e os parâmetros de fluorescência foram afetados pelas doses de glyphosate, mas não pela variação do tamanho do vaso. Não houve interação significativa entre doses e tamanhos de vasos sobre a eficácia de controle, porém essa variável aumentou consideravelmente com o aumento da dose e, discretamente, com o aumento do tamanho de vaso, sobretudo nas avaliações até os 14 DAA. A matéria seca da parte área aos 28 DAA e de rebrota foi dependente da interação entre tamanho do vaso e dose de glyphosate. O tamanho do vaso deve ser escolhido com critério para ensaios de eficácia de controle de B. decumbens com herbicida sistêmico. ABSTRACT The aim of this work was to evaluate pot size and glyphosate rate interaction on the growth, physiology and control of Brachiaria decumbens weed. It was sowed in 2, 5, 10 and 20 L-pots, which were kept in greenhouse. Plant growth was assessed from 41 to 63 days after plant emergence (DAE). Glyphosate was applied to all pot sizes at 0.0, 0.8, 1.6 and 3.2 kg ha-1, at 64 DAE. Leaf gas exchange was assessed along with chlorophyll fluorescence at two days after application (DAA); weed control level at 7, 14, 21 and 28 DAA; weed dry matter at 28 DAA; and weed sprouting dry matter at 28 days after weed cutting. B. decumbens growth increased linearly with increased pot size. Both weed gas exchange and chlorophyll fluorescence parameters were affected by glyphosate rates, but not by pot size. No significant interaction between glyphosate doses and pot size on weed control levels was found, but it increased strongly with increasing herbicide rates and only slightly with pot size, particularly up to 14 DAA. Weed dry matter at 28 DAA and plant regrowth differed according to pot size and glyphosate dose interaction. It was concluded that pot size should be precisely chosen to test systemic herbicide efficacy on the control of B. decumbens.

Objetivou-se com este trabalho avaliar os efeitos da interferência de plantas daninhas, em diferentes densidades de infestação, sobre o crescimento de plantas jovens de café arábica. Mudas de café, cultivar Mundo Novo, foram transplantadas, no estádio de quatro a cinco pares de folhas completamente expandidas, para vasos com capacidade de 25 dm3. O experimento foi conduzido em casa de vegetação em blocos casualizados, em esquema fatorial (4 x 4); o primeiro fator foi composto por espécies de plantas daninhas (Digitaria horizontalis, Brachiaria decumbens, Brachiaria plantaginea e Mucuna aterrima), e o segundo, por densidades dessas espécies (zero, dois, quatro e seis plantas por vaso), com quatro repetições. O plantio das espécies daninhas foi realizado 60 dias após o transplantio do café (0 DAT). Nesta data e no dia do encerramento do experimento, aos 90 DAT, determinaram-se a altura, a área foliar e o diâmetro do caule da planta de café, para cálculo do incremento dessas variáveis. Aos 90 DAT, determinou-se a matéria seca da parte aérea e radicular do café e das plantas daninhas e a densidade radicular do café. Utilizando esses resultados, estimou-se a razão de massa foliar, razão de massa caulinar, razão de massa radicular, razão de área foliar e a razão sistema radicular/parte aérea das plantas de café. A espécie M. aterrima foi a que mais reduziu a taxa de crescimento, a área foliar, a matéria seca do caule e das folhas e o diâmetro do caule do café. Entre as gramíneas, B. plantaginea foi a que mais reduziu a taxa de crescimento, área foliar, diâmetro do caule e densidade radicular do café. Ocorreu relação negativa entre a densidade de plantas daninhas e as variáveis de crescimento e com a razão de massa radicular e razão sistema radicular/parte aérea. The goal of this work was to evaluate the effects of weeds on the growth of young Arabica coffee plants, at different densities of infestation. Seedlings of Mundo Novo coffee cultivar were transplanted at the stage of four to five pairs of completely expanded leaves, to pots with capacity of 25 dm3. The experiment was arranged in a randomized block in factorial design (4 x 4), with four weed species (Digitaria horizontalis, Brachiaria decumbens, Brachiaria plantaginea and Mucuna aterrima) at four planting densities coexisting with coffee (zero, two, four, and six plants per pot), with four replications. The weed species were planted 60 days after the coffee plant transplanting (0 DAT). On this date, and on the day the experiment was concluded, at 90 DAT, height, leaf area and stem diameter of the coffee plants were determined. At 90 DAT, measurements were also performed to determine the increase in height, leaf area and stem diameter of the coffee plants, as well as shoot and root dry matter of the coffee plants and weeds and coffee plant root density. Based onthese data, estimations were made for leaf mass ratio, stem mass ratio, root mass ratio, leaf area ratio and root system/shoot ratio of the coffee plants. The species M. aterrima presented the highest reduction rate for plant height, leaf area, dry matter of stem and leaves and girth diameter of the coffee plants. Among the grasses, B. plantaginea presented the highest reduction rate for plant height, leaf area, girth diameter and root density. A negative relation was observed between weed increase and growth variables, and between root mass ratio and root system/shoot ratio.

Summary The aim of this study was to evaluate the effect of 2,4-dichlorophenoxyacetic acid (2,4-D) applied as a herbicide at two timings after coffee blossoming, on fruit shedding from lower or upper plagiotropic branches on the canopy, as well as on crop yield. 2,4-D was sprayed between the rows on a 0.75 m-wide strip of land, starting on the border of canopy projection. Toxicity to the plants, final crop yield per plant and fruit shedding (FS) were assessed. The identical FS was observed for both application timings. Control plots showed an FS 13% lower than those where the highest 2,4-D dose was employed. FS was greater on the lower branches (46.8%) than on the upper ones (39.4%). This was probably due to injury to the lower plant canopy caused by the 2,4-D drift. Ripe or dried cherries and coffee bean yield per plant were not affected. It was concluded that despite the increased FS in the lower plant canopy, final coffee production was not significantly affected in response to 2,4-D application.

Este trabalho teve como objetivo avaliar a tolerância de mudas de café à aplicação de herbicidas em pós-emergência. Flumiozaxin, sulfentrazone, flazasulfuron, clethodim, fluazifop-p-butil, imazamox, bentazon, fomesafen, lactofen, oxyfluorfen, chlorimuron-ethil, metribuzin e também as misturas de fluazifop-p-butil + fomesafen e de nicosulfuron + atrazine foram aplicados diretamente sobre o topo das plantas, 15 dias após o transplantio das mudas de café para os vasos (3,0 L). Foram feitas avaliações visuais de toxicidade dos herbicidas às plantas de café e, também, avaliações da altura, do diâmetro e da massa seca da parte aérea e das raízes dessas plantas. O metribuzin e a mistura em tanque de nicosulfuron + atrazine causaram morte das plantas de café, enquanto imazamox, sulfentrazone, oxyfluorfen e lactofen causaram severa toxicidade (49 a 64%). Dentre os herbicidas avaliados, aqueles que mais reduziram a altura das plantas, em relação à testemunha, foram imazamox e sulfentrazone (62 e 68%, respectivamente). O acúmulo de matéria seca, tanto da parte aérea como do sistema radicular, foi no máximo 67% daquele apresentado pela testemunha para sulfentrazone, flazasulfuron, imazamox, lactofen e oxyfluorfen. O maior potencial para uso em pós-emergência, sobre o topo das plantas, foi obtido com fluazifop-p-butil, clethodim, fomesafen, chlorimuron-ethil, flumioxazin e fluazifop-p-butil + fomesafen, uma vez que causaram apenas leves injúrias e não afetaram o acúmulo de matéria seca do cafeeiro. This work was conducted to evaluate the tolerance of coffee plant seedlings to post emergence herbicide application. Flumiozaxin, sulfentrazone, flazasulfuron, clethodim, fluazifop-p-butil, imazamox, bentazon, fomesafen, lactofen, oxyfluorfen, chlorimuron-ethil, metribuzin and also the mixtures of fluazifop-p-butil + fomesafen and of nicosulfuron + atrazine were sprayed directly on top of the plants, 15 days after coffee seedling transplantation, in 3.0 L pots. Herbicide injury, coffee plant height, diameter and also shoot and root dry weights were evaluated. Whereas imazamox, sulfentrazone, oxyfluorfen and lactofen imposed a high injury (49 to 64%), metribuzin and the nicosulfuron + atrazine tank mixture killed all the plants 35 days after application. The greatest plant height decreases were imposed by imazamox (62%) and sulfentrazone (68%). Both the shoot and the root dry matter contents were a maximum of 67% of that verified on the control, after applications of sulfentrazone, flazasulfuron, imazamox, lactofen and oxyfluorfen. The greatest potential to post emergence application on top of the plants were achieved with fluazifop-p-butyl, clethodim, fomesafen, chlorimuron-ethyl, flumioxazin and fluazifop-p-butyl + fomesafen, since they neither significantly injured the plants nor affected their dry matter production.

As plantas jovens de café são muito sensíveis à interferência das plantas daninhas, devido à forte competição por nutrientes que se estabelece entre essas plantas. Este trabalho teve como objetivo, portanto, avaliar os efeitos da interferência de sete espécies de plantas daninhas no conteúdo relativo (CR) de macro e micronutrientes, na massa seca da parte aérea de plantas de café. Aos 30 dias após o transplantio das mudas de café, em vasos contendo 12 L de substrato, fez-se o transplantio e/ou a semeadura das espécies daninhas, em seis densidades (0, 1, 2, 3, 4 e 5 plantas por vaso). Os períodos de convivência, desde o transplantio ou emergência das plantas daninhas até a colheita das plantas, foram de 77 dias - Bidens pilosa, 180 dias - Commelina diffusa, 82 dias - Leonurus sibiricus, 68 dias - Nicandra physaloides, 148 dias - Richardia brasiliensis e 133 dias - Sida rhombifolia. B. pilosa, C. diffusa, L. sibiricus e R. brasiliensis, mesmo em baixas densidades, acarretaram decréscimos consideráveis no conteúdo relativo de nutrientes de plantas de café. B. pilosa foi a planta daninha que extraiu a maior quantidade de nutrientes, enquanto N. physaloides e S. rhombifolia foram as espécies que causaram menor interferência ao cafeeiro. O grau de interferência variou com a espécie e com a densidade das plantas daninhas. Young coffee plants are very sensitive to weed interference due to the high nutrient competition among these plants. This work was conducted to evaluate the interference effects of seven weed species on the relative contents (RC) of macro and micro-nutrients in coffee shoot dry matter. At 30 days after coffee seedling transplantation in 12 L pots, the weeds were transplanted to or sowed in those pots (0, 1, 2, 3, 4 and 5 plants per pot). The weedy periods, from weed transplantation or emergence to plant harvesting, were 77 days - Bidens pilosa, 180 days - Commelina diffusa, 82 days - Leonurus sibiricus, 68 days - Nicandra physaloides, 148 days - Richardia brasiliensis and 133 days - Sida rhombifolia. B. pilosa, C. diffusa, L. sibiricus and R. brasiliensis caused considerable decreases in the nutrient RC of the coffee plants, even at low densities. B. pilosa absorved the highest nutrient amounts, while N. physaloides and S. rhombifolia caused the least interference in coffee plants. The degree of interference depended both on the species and density of the weeds.

Este trabalho teve como objetivo avaliar a eficiência de misturas de herbicidas no controle de duas espécies de trapoeraba, Commelina diffusa e Commelina benghalensis. Para isso, segmentos de caule dessas espécies foram transplantados em vasos contendo 12 L de substrato. Após 120 dias, foram aplicados os seguintes tratamentos: carfentrazone-ethyl (30 g ha1) em mistura com glyphosate (720 g ha-1) e/ou glyphosate potássico (720 g ha-1); glyphosate (720 g ha-1) em mistura com flumioxazin (60 g ha-1) e/ou 2,4-D (670 g ha-1) e/ou metsulfuron methyl (4 g ha-1); oxyfluorfen em mistura com sulfentrazone (480 + 375 g ha1); aplicações seqüenciais, com intervalo de 21 dias, de [(paraquat + diuron) / (carfentrazone-ethyl + glyphosate)] [(200+400)/(30+720)] e de [(paraquat + diuron) / (paraquat + diuron)] [(200+400)/(200+400)]; e testemunha sem aplicação de herbicida. Cada espécie constituiu um experimento, sendo ambos conduzidos no delineamento em blocos casualizados, com quatro repetições. Foram feitas avaliações de controle das trapoerabas e da biomassa fresca da parte aérea. Os tratamentos mais eficientes no controle das trapoerabas foram as aplicações seqüenciais, com intervalo de 21 dias, de (paraquat + diuron) / (carfentrazone-ethyl + glyphosate) e de (paraquat + diuron) / (paraquat + diuron), seguidas das misturas em tanque de 2,4-D + glyphosate e de carfentrazone-ethyl + glyphosate e/ou glyphosate potássico. This research was conducted to evaluate the efficiency of herbicide mixtures in the control of two dayflower species, Commelina diffusa and Commelina benghalensis. These species were grown from stem segments in 12 L pots during 120 days. Subsequently, a randomized complete block design with four replicates was performed for each species. The treatments were carfentrazone-ethyl combined to either glyphosate or glyphosate-potassium salt (30 + 720 g ha-1); glyphosate (720 g ha-1) combined to flumioxazin (60 g ha-1), or 2.4-D (670 g ha-1) or metsulfuron methyl (4 g ha-1); oxyfluorfen combined to sulfentrazone (480 + 375 g ha-1); sequential 21 day-spaced applications of (paraquat + diuron) / (carfentrazone-ethyl + glyphosate) (200+400) /(30+720) and (paraquat + diuron) / (paraquat + diuron) (200+400) / (200+400); and no herbicide application as check control. The percentage of weed control and shoot fresh weight were evaluated. The best treatments to control both species were the sequential applications of (paraquat + diuron) / (carfentrazone-ethyl + glyphosate) and of (paraquat + diuron) / (paraquat + diuron), followed by 2.4-D + glyphosate and carfentrazone-ethyl + glyphosate or glyphosate-potassium salt mixtures.

Esta pesquisa teve como objetivo avaliar a eficácia do herbicida carfentrazone-ethyl, isolado ou associado ao glyphosate e ao glyphosate potássico, no controle de duas espécies de plantas daninhas conhecidas como trapoeraba: Commelina diffusa e Commelina benghalensis. Para isso, segmentos de caule dessas plantas foram transplantados e submetidos a crescimento em vasos que continham 12 L de substrato, durante 120 dias. Os experimentos (um por espécie de trapoeraba) foram conduzidos no delineamento experimental em blocos casualizados, com quatro repetições, sendo constituídos de carfentrazone-ethyl nas doses de 0, 10, 20, 30, 40 e 50 g ha1, isoladas ou aplicadas em mistura com o glyphosate e o glyphosate potássico, ambos na dose de 720 g ha-1. Foram feitas avaliações de controle e da biomassa fresca da parte aérea (BFPA). C. diffusa foi mais tolerante ao carfentrazone-ethyl e à sua mistura ao glyphosate e ao glyphosate potássico do que C. benghalensis. Tanto o glyphosate quanto o glyphosate potássico, isolados, promoveram controle considerado ruim (inferior a 30%) de ambas as espécies de trapoeraba, na dose de 720 g ha-1. A eficiência de controle pelas misturas de herbicidas foi superior à das suas aplicações isoladas, com exceção do carfentrazone-ethyl em doses acima de 30 g ha-1, as quais proporcionaram controles de C. benghalensis semelhantes às misturas. Apesar do razoável controle (de 71 a 80%) para C. diffusa e do bom a excelente controle (acima de 81%) para C. benghalensis, proporcionados pelas misturas de carfentrazone-ethyl com glyphosate e/ou glyphosate potássico, apenas uma aplicação não foi suficiente para o controle definitivo da Commelina spp., pois verificou-se para ambas as espécies, por meio da avaliação da BFPA, a reinfestação da área devido à recuperação das plantas, ou mesmo, no caso de C. benghalensis, a reinfestação a partir de sementes subterrâneas, que se tornaram viáveis após a morte da parte aérea provocada pelos herbicidas. This research was conducted to evaluate the effectiveness of carfentrazone-ethyl, isolated and in mixture with to glyphosate or glyphosate-potassium salt, on controlling two dayflower species, Commelina diffusa and C. benghalensis. These species were grown from stem segments in 12 L pots filled with soil, during 120 days. A complete randomized block design with four replicates was performed for each species. The treatments were carfentrazone-ethyl (0, 10, 20, 30, 40 and 50 g ha-1), isolated and in mixture with glyphosate or glyphosate-potassium salt, these being applied at doses of 720 g ha-1. The percentages of weed control and shoot fresh weight (SFW) were evaluated. C. diffusa was more tolerant to carfentrazone-ethyl alone or combined with both glyphosate and glyphosate-potassium salt than C. benghalensis. Both glyphosate and glyphosate-potassium salt were inefficient (control below 30%) when applied isolated, regardless of the species. The efficiency of controlling herbicide mixtures was greater than their single applications, except for the carfentrazone-ethyl in doses above 30 g ha-1, with C. benghalensis, in which control was similar to the employed mixtures. Despite the reasonable control (from 71 to 80%) for C. diffusa and the very good control (above 81%) for C. benghalensis, obtained with carfentrazone-ethyl + glyphosate or carfentrazone-ethyl + glyphosate-potassium salt mixtures, a sole application did not decisively control Commelina spp. In effect, recovery of plants as seen through SFW evaluation took place irrespective of the species; moreover, for C. benghalensis, reinfestation from underground seeds that became viable after the shoot's death, due to herbicide application, was also found.

Este trabalho teve por objetivo avaliar a seletividade do oxyfluorfen e do sulfentrazone e o controle de plantas daninhas em diferentes épocas após o transplantio das mudas de café no campo. Foram realizados três ensaios no delineamento experimental de blocos casualizados com dez tratamentos e quatro repetições. No ensaio 1, aos 30 dias após o transplantio (DAT) e, no ensaio 2, aos 90 DAT, testaram-se duas doses de oxyfluorfen (0,36 e 0,72 kg i.a. ha-1) e de sulfentrazone (0,4 e 0,6 kg i.a. ha-1), em jato dirigido ao solo (com proteção das mudas) e em área total. No ensaio 3, os mesmos herbicidas e doses foram aplicados, porém aos 300 DAT e apenas em aplicação dirigida, testando-se duas pontas de pulverização de diferentes potenciais de deriva. Em todos os ensaios, acrescentaram-se as testemunhas capinada e sem capina. A entrelinha foi manejada com roçada. Foram identificadas as espécies de plantas daninhas e suas densidades. A eficácia dos herbicidas e suas seletividades também foram avaliadas. A principal planta daninha que ocorreu na área experimental foi Brachiaria decumbens. Sintomas visuais de toxicidade foram observados apenas quando os herbicidas foram aplicados em área total (ensaios 1 e 2), independentemente da dose e época de aplicação. No ensaio 3, independentemente do herbicida, da dose e da ponta utilizada, não houve sintomas visuais de toxicidade, nem redução no crescimento das plantas, em função da aplicação dirigida. Em todas as épocas o controle de plantas daninhas foi eficiente, porém a seletividade só foi alcançada na aplicação dirigida, para ambos os herbicidas. This study aimed to evaluate oxyfluorfen and sulfentrazone selectivity and weed control in young coffee plantations (Coffea arabica cv. Red Catuaí). Three trials were conducted in a randomized complete block design, with 10 treatments and four replicates. In the first and second trials, at 30 and 90 days after transplanting (DAT), respectively, two doses of oxyfluorfen (0.36 and 0.72 kg a.i. ha-1) and sulfentrazone (0.4 and 0.6 kg a.i. ha-1) were tested by spraying the herbicides directly into soil (with seedling protection) or onto the total area. The same herbicides and doses were used in the third trial, but at 300 DAT and only directed to the soil, using two sprayer nozzles with different drift potentials being tested. Two additional control plots were added: hand-weeding control and weedy treatments. Weeds present in the inter-row spaces were eliminated by mowing operations. Weeds and their densities were identified. The toxicity of the herbicides to the coffee plants and its effectiveness in controlling the weeds were assessed. The main weed occurring in the experimental area was Brachiaria decumbens. Visual symptoms of herbicide toxicity were observed only when the herbicides were applied in the entire area (trials 1 and 2), regardless of their doses and application times. At the third herbicide application trial, no visual symptoms of herbicide toxicity and no reductions in plant growth were observed, regardless of the herbicide, the dose and the sprayer nozzles tested. At all times, a very good weed control percentage was obtained, but selectivity occurred only when the herbicides were not applied onto the total area.

O objetivo deste estudo consistiu em determinar a faixa ideal de controle de plantas daninhas (FCPD) necessária para um crescimento adequado do cafeeiro após o transplantio. Foi utilizada uma lavoura não irrigada, implantada no espaçamento de 3,80 x 0,70 m, em dezembro de 2008. O delineamento experimental foi em blocos casualizados, com quatro repetições. Os tratamentos foram dispostos em um esquema de parcelas subdivididas (9 x 18) para testar as FCPDs de 0, 15, 30, 45, 60, 90, 120, 150 e 190 cm, mantidas com capina contínua em cada lado da linha de café, bem como seus efeitos ao longo de 18 meses após o transplantio (MAT). Efetuaram-se análises de regressão múltipla que relacionaram as variáveis de crescimento em função da FCPD e das épocas de avaliação do crescimento. A principal espécie identificada foi a poácea Brachiaria decumbens, com 88,5% da matéria seca total das plantas daninhas. A largura mínima da FCPD aumentou com a idade da cultura após o transplantio. Assumindo reduções de 2 e 5% no crescimento máximo do cafeeiro, as FCPDs recomendadas foram de 75 e 52 cm aos 4 MAT, 104 e 85 cm aos 6 MAT, 123 e 105 cm aos 9 MAT, 134 e 116 cm aos 12 MAT, 142 e 124 cm aos 15 MAT e 148 e 131 cm aos 18 meses após o transplantio, respectivamente. Conclui-se que o manejo das plantas daninhas em lavouras jovens de café deve buscar a manutenção apenas de uma faixa de controle mínima na linha de plantio, cuja largura aumenta com a idade da lavoura, preservando a vegetação na entrelinha. The aim of this study was to determine the weed strip control (WSC) required for adequate coffee growth after transplanting. A non-irrigated, field-planted (spaced 3.80 x 0.70 m) crop was used. The experimental design was a randomized block, with four replicates. The treatments were arranged in a 9 x 18 split-plot design to test the WSC of 0, 15, 30, 45, 60, 90, 120, 150, and 190 cm, which involved continuously hand-weeding at each side of the coffee row, and 18 coffee growth measurements. Multiple regression analyses were carried out relating to growth-variables as a function of both WSC and growth-evaluation times. Brachiaria decumbens was the main weed accomplishing 88.5% of the total weed dry mass. The minimum width of the WSC increases as the crop ages after transplanting. Assuming reductions of 2% and 5% in the maximum coffee growth, the recommended WSC was 75 and 52 cm at 4 months after transplanting (MAT), 104 and 85 cm at 6 MAT, 123 and 105 cm at 9 MAT, 134 and 116 cm at 12 MAT, 142 and 124 cm at 15 MAT, and 148 and 131 cm at 18 MAT, respectively. It was concluded that integrated weed management in young coffee crops must focus on the weed control only in a minimum range along coffee rows, which increases with coffee plant age, keeping natural vegetation in the inter-rows.

Avaliaram-se, neste trabalho, os efeitos do glyphosate sobre os teores foliares de nutrientes em três cultivares de café (Coffea arabica). Utilizou-se o esquema fatorial (3 x 5) em delineamento de blocos casualizados, com quatro repetições, sendo os tratamentos compostos por três cultivares de café: Catucaí Amarelo (2 SL), Oeiras (MG-6851) e Topázio (MG-1190); e cinco doses de glyphosate (0; 57,6; 115,2; 230,4; e 460,8 g ha-1). Aos 45 e 120 DAA, coletaram-se folhas (terceiro par) de ramos plagiotrópicos, contidos na parte mediana das plantas. Os sintomas de intoxicação foram caracterizados por clorose e estreitamento do limbo foliar para os três cultivares de café. Houve redução nos teores foliares de N, P, K, Cu e Zn aos 45 DAA e de N, K, Mn e Zn aos 120 DAA nas plantas de café tratadas com glyphosate, independentemente do cultivar utilizado. O cultivar Topázio apresentou as maiores reduções nos teores foliares de Fe e Mn, aos 45 DAA, e de P e Fe, aos 120 DAA. The effects of glyphosate on the foliar levels of nutrients in three coffee cultivars (Coffea arabica) were evaluated in this work. A factorial (3 x 5) was used in a randomized block design with four replications, with treatments consisting of three coffee varieties: Catucaí Amarelo (2 SL), Oeiras (MG-6851) and Topázio (MG-1190) and five glyphosate doses (0, 57.6, 115.2, 230.4 and 460.8 g ha-1). At 45 and 120 DAA, leaves (third pair) from plagiotrophic branches were collected from the medium part of the plants. Glyphosate intoxication symptoms were characterized by chlorosis and leaf narrowing for the three coffee varieties. There was a reduction in foliar levels of N, P, K, Cu and Zn at 45 DAA, and N, K, Mn and Zn at 120 DAA, in coffee plants treated with glyphosate, regardless of the cultivar used. Cultivar Topázio showed the greatest reductions in the foliar levels of Fe and Mn, at 45 DAA and P and Fe, at 120 DAA, when treated with glyphosate.

O tomate (Lycopersicon esculentum) é a segunda hortaliça em importância no Brasil. O controle de plantas daninhas na cultura representa um dos principais componentes do custo de produção, sendo imprescindível para a obtenção de produtividades elevadas e de frutos de qualidade. Neste texto são apresentados de forma detalhada os efeitos adversos da interferência das plantas daninhas sobre a cultura, tanto daquele cultivado a partir de mudas transplantadas como de semeadura direta. Também são discutidos, para diferentes situações de cultivo, aspectos sobre o período crítico de competição das plantas daninhas durante o ciclo da cultura. Por fim, são apresentadas as principais estratégias utilizadas para o controle de plantas daninhas na cultura do tomateiro, por meio de medidas preventivas, culturais, mecânicas e químicas, com base nas informações atualmente disponíveis sobre esse tema. Tomato (Lycopersicon esculentum) is the second most important vegetable grown in Brazil. Weed control in tomato culture is one of the main components in crop production costs. However, weed management is indispensable to achieve both high yields and fruit quality. A detailed discussion is presented in this work concerning the adverse effects of weed interference in the crop, both grown from transplanted seedlings and field-sown tomato. Aspects related to the critical period of weed competition during the crop cycle for both growing conditions are also discussed. Finally, the major strategies used for weed management in tomato crops are also presented, such as preventive, cultural, mechanic, and chemical control measures, based on the literature currently available.

Apesar de o controle de plantas daninhas na cultura do mamoeiro representar um dos componentes de grande importância do custo de produção, no mundo e no Brasil, a disponibilidade de informações sobre esse tema é escassa, o que reflete a pouca importância que tem sido dada ao assunto nas últimas décadas. Neste texto são discutidos alguns avanços no manejo integrado de plantas daninhas que têm sido alcançados em vários países, particularmente no tocante à manutenção da vegetação natural ou à introdução de leguminosas na entrelinha de cultivo. Não obstante, várias espécies de plantas daninhas foram identificadas como hospedeiras de vetores de importantes viroses à cultura, com destaque para Commelina benghalensis e Solanum americanum. Isso se reveste de grande importância para o manejo (seletivo) das plantas daninhas, sobretudo na produção integrada de mamão. Também são discutidos, em especial para a região norte do Estado do Espírito Santo, a seletividade de herbicidas, os períodos de controle e as principais características e aspectos práticos sobre o manejo de plantas daninhas na cultura do mamoeiro. Despite the fact that weed control entails high costs to crop production, the availability of national and international papers regarding papaya weed control is scarce, showing that little importance has been given to this subject in the last decades. Some integrated weed management advances attamed in several countries are discussed, particularly in the use of both natural groundcover or leguminous plants in the crop interrows. However, several weed species have been identified as host plants of major virus vectors to the crop, such as C. benghalensis and S. americanum. Such information is of major importance for selective weed control, particularly in the integrated system of papaya production. The present review also examined herbicide selectivity, weedy periods as well as the main characteristics and practical aspects of weed control in papaya, focusing on the production areas of the northern Espírito Santo State.

After oil, coffee is the most valuable traded commodity worldwide. In this review we highlighted some aspects of coffee growth and development in addition to focusing our attention on recent advances on the (eco)physiology of production in both Coffea arabica and C. canephora, which together account for 99% of the world coffee bean production. This review is organized into sections dealing with (i) climatic factors and environmental requirements, (ii) root and shoot growth, (iii) blossoming synchronisation, fruiting and cup quality, (iv) competition between vegetative and reproductive growth and branch die-back, (v) photosynthesis and crop yield, (vi) physiological components of crop yield, (vii) shading and agroforestry systems, and (viii) high-density plantings. O cafeeiro, depois do petróleo, é a principal mercadoria comercializada no mundo. Nesta revisão, analisam-se aspectos do crescimento e desenvolvimento do cafeeiro, dando-se, também, ênfase aos avanços recentes sobre a (eco)fisiologia da produção de Coffea arabica e C. canephora, que respondem por cerca de 99% da produção mundial de café. Abordam-se (i) os fatores climáticos e requerimentos ambientes, (ii) crescimento da parte aérea e das raízes, (iii) sincronização da floração, frutificação e qualidade da bebida, (iv) competição entre os crescimentos vegetativo e reprodutivo e ocorrência de seca de ramos; (v) fotossíntese e produção, (vi) componentes fisiológicos da produção, (vii) sombreamento e sistemas agroflorestais, e (viii) plantios adensados.

The effects of competition of six weed species on growth, nutrient concentration and nutrient content of coffee plant root system under greenhouse conditions were evaluated. Thirty days after coffee seedling transplantation into 12 L pots with soil level area of 6.5 dm². Weeds were transplanted or sowed in these pots, at densities of 0, 1, 2, 3, 4 and 5 plants per pot. The duration of competition (or weedy periods) from weed transplantation or emergence until plant harvesting, at the weed preflowering stage, were (in days): 77 (Bidens pilosa), 180 (Commelina diffusa), 82 (Leonurus sibiricus), 68 (Nicandra physaloides), 148 (Richardia brasiliensis) and 133 (Sida rhombifolia). Dry matter of coffee plants was linearly reduced with increasing B. pilosa and S. rhombifolia density, with pronounced effect of B. pilosa. C. diffusa was the only weed species whose increasing density in the pots did not diminish crop root dry matter. L. sibiricus, N. physaloides and R. brasiliensis reduced root dry matter of coffee plants by 75, 52 and 47%, respectively, as compared to the weed-free treatment, regardless of weed density. Under competition, even though weed species showed lower macronutrient concentration in the roots (except for P), they accumulated 4.2 (N), 12.3 (P), 4.3 (K), 5.5 (Ca), 7.6 (Mg) and 4.4 (S) times more nutrients in the roots than the coffee plants. Crop and weed nutrient concentration, as well as competition degrees greatly varied depending on both weed species and densities. Este trabalho teve como objetivo avaliar os efeitos da competição de seis espécies de plantas daninhas sobre o crescimento, a concentração e o conteúdo de nutrientes no sistema radicular de plantas de café, cultivadas em casa de vegetação. Aos 30 dias após o transplantio das mudas de café, em vasos contendo 12 L de substrato e com área de 6,5 dm² na superfície do solo, fez-se o transplantio e, ou, a semeadura das espécies daninhas nesses vasos, em seis densidades (0, 1, 2, 3, 4 e 5 plantas por vaso). Os períodos de convivência, desde o transplantio ou emergência das plantas daninhas até a colheita das plantas, quando do florescimento das plantas daninhas, foram (em dias): 77 (Bidens pilosa), 180 (Commelina diffusa), 82 (Leonurus sibiricus), 68 (Nicandra physaloides), 148 (Richardia brasiliensis) e 133 (Sida rhombifolia). A massa seca do sistema radicular das plantas de café reduziu-se linearmente com o aumento da densidade de B. pilosa e de S. rhombifolia, com efeito mais pronunciado em B. pilosa. C. diffusa foi a única espécie que não reduziu o acúmulo de matéria seca no sistema radicular das plantas de café. L. sibiricus, N. physaloides e R. brasiliensis reduziram a massa seca da raiz do café em 75, 52 e 47%, respectivamente, comparado ao tratamento livre de interferência, independentemente da densidade de plantas daninhas. Sob competição, apesar de apresentarem, no seu sistema radicular, concentrações de macronutrientes (exceto para P) inferiores àquelas do café, as plantas daninhas acumularam 4,2 (N), 12,3 (P), 4,3 (K), 5,5 (Ca), 7,6 (Mg) e 4,4 (S) vezes mais nutrientes nas raízes que as plantas de café. A concentração de nutrientes no café e nas plantas daninhas, assim como o grau de interferência dessas plantas, variaram fortemente com a espécie e densidade de planta daninha.

Este trabalho foi realizado com o objetivo de investigar, em campo, a eficiência de vários herbicidas aplicados em pós-emergência em área total no controle de plantas daninhas, em cafezais recém-implantados e no consórcio de café e feijão, assim como seus efeitos sobre essas culturas. Mudas de Coffea arabica, cultivar Catuaí Vermelho, com quatro a seis pares de folhas foram transplantadas para o campo e cultivadas segundo práticas agronômicas usuais. O consórcio de café e feijão foi obtido por meio do plantio de três linhas de feijão nas entrelinhas do cafezal. Quando os herbicidas foram aplicados sobre as culturas, as plantas de café estavam com seis a dez pares de folhas, as de feijão com três folíolos e as plantas daninhas no estádio inicial de desenvolvimento. Fluazifop-p-butil e clethodim foram seletivos às plantas de café e controlaram eficientemente Brachiaria plantaginea e Digitaria horizontalis. Plantas daninhas dicotiledôneas (Amaranthus retroflexus, Bidens pilosa, Coronopus didymus, Emilia sonchifolia, Galinsoga parviflora, Ipomoea grandifolia, Lepidium virginicum e Raphanus raphanistrum) foram controladas eficientemente por aplicações isoladas de fomesafen, flazasulfuron e oxyfluorfen, com exceção de B. pilosa, C. didymus e R. raphanistrum para o oxyfluorfen. Aplicações seqüenciais com intervalos de sete dias de fomesafen + fluazifop-p-butil ou clethodim, e as duas misturas comerciais de fomesafen + fluazifop-p-butil controlaram simultaneamente ambos os tipos de plantas daninhas. Cyperus rotundus foi controlada apenas por flazasulfuron. Com exceção de fluazifop-p-butil e clethodim todos os demais tratamentos herbicidas provocaram apenas leves injúrias às folhas mais novas das plantas de café. Contudo, o crescimento das plantas não foi prejudicado, de forma que tanto a altura como o diâmetro do caule do cafeeiro foram os mesmos entre tratamentos, em avaliações realizadas quatro meses após suas aplicações. Fomesafen, fluazifop-p-butil e clethodim, em aplicações isoladas ou seqüenciais, e as misturas comerciais de fomesafen + fluazifop-p-butil foram também seletivos para a cultura do feijão, podendo, portanto, nas doses recomendadas para esta cultura, ser usadas para controle de plantas daninhas no consórcio de café e feijão, em aplicação em área total. This study was carried out to investigate the efficiency of several herbicides under field conditions, by post-emergence application onto the entire area, their effect on the control of weeds in young coffee plantations and commercial coffee and bean intercropping system, as well as on both crops. Seedlings of Coffea arabica cv. Red Catuaí with four to six leaf pairs were transplanted to the field and treated according to conventional agronomic practices. A bean and coffee intercropping system was established by sowing three lines of beans in the coffee inter-rows. At the time the herbicides were sprayed, the coffee plants had six to ten leaf pairs; the bean plants, three leaflets; and the weeds were at an early development stage. Fluazifop-p-butyl and clethodim were selective for coffee plants and controlled only Brachiaria plantaginea and Digitaria horizontalis efficiently. Broad-leaved weeds (Amaranthus retroflexus, Bidens pilosa, Coronopus didymus, Emilia sonchifolia, Galinsoga parviflora, Ipomoea grandifolia, Lepidium virginicum, and Raphanus raphanistrum) were controlled with high efficiency by sole applications of fomesafen, flazasulfuron, and oxyfluorfen, except B. pilosa, C. didymus, and R. raphanistrum for oxyfluorfen. Sequential applications in seven-day intervals of fomesafen + fluazifop-p-butyl, or clethodim, and two commercial mixtures of fomesafen + fluazifop-p-butyl simultaneously controlled both types of weed. Cyperus rotundus was only controlled by flazasulfuron. Except for fluazifop-p-butyl and clethodim, all herbicide treatments caused only slight injuries on younger coffee leaves. However, further plant growth was not impaired and coffee plant height and stem diameter were therefore similar in the treatments, as evaluated four months later. Fomesafen, fluazifop-p-butyl, and clethodim, at sole or sequential application, and the commercial mixtures of fomesafen + fluazifop-p-butyl were also highly selective for bean crop; thus at doses recommended for bean crop, these herbicides may be applied to control weeds in coffee and bean intercropping systems by spraying the entire area.

Coffee (Coffea arabica L.) plants were grown in small (3-L), medium (10-L) and large (24-L) pots for 115 or 165 d after transplanting (DAT), which allowed different degrees of root restriction. Effects of altered source : sink ratio were evaluated in order to explore possible stomatal and non-stomatal mechanisms of photosynthetic down-regulation. Increasing root restriction brought about large and general reductions in plant growth associated with a rising root : shoot ratio. Treatments did not affect leaf water potential or leaf nutrient status, with the exception of N content, which dropped significantly with increasing root restriction even though an adequate N supply was available. Photosynthesis was severely reduced when plants were grown in small pots; this was largely associated with non-stomatal factors, such as decreased Rubisco activity. At 165 DAT contents of hexose, sucrose, and amino acids decreased in plants grown in smaller pots, while those of starch and hexose-P increased in plants grown in smaller pots. Photosynthetic rates were negatively correlated with the ratio of hexose to free amino acids, but not with hexose content. Activities of acid invertase, sucrose synthase, sucrose-P synthase, fructose-1,6-bisphosphatase, ADP-glucose pyrophosphorylase, starch phosphorylase, glyceraldehyde-3-P dehydrogenase, PPi : fructose-6-P 1-phosphotransferase and NADP : glyceraldehyde-3-P dehydrogenase all decreased with severe root restriction. Glycerate-3-P : Pi and glucose-6-P : fructose-6-P ratios decreased accordingly. Photosynthetic down-regulation was unlikely to have been associated directly with an end-product limitation, but rather with decreases in Rubisco. Such a down-regulation was largely a result of N deficiency caused by growing coffee plants in small pots.

Este trabalho teve como objetivo avaliar os efeitos da competição de sete espécies de plantas daninhas sobre o crescimento de plantas de café, cultivadas em casa de vegetação. Aos 30 dias após o transplantio das mudas de café, em vasos contendo 12 L de substrato e com área de 6,5 dm2 na superfície do solo, fez-se o transplantio e/ou a semeadura das espécies daninhas nesses vasos, em seis densidades (0, 1, 2, 3, 4 e 5 plantas por vaso). Os períodos de convivência, desde o transplantio ou emergência das plantas daninhas até a colheita das plantas, quando do florescimento das plantas daninhas, foram de 77 dias - Bidens pilosa, 180 dias - Commelina diffusa, 82 dias - Leonurus sibiricus, 68 dias - Nicandra physaloides, 148 dias - Richardia brasiliensis e 133 dias - Sida rhombifolia. Foram avaliados a altura de plantas, o diâmetro do caule, o número de folhas e a massa seca da parte aérea das plantas de café. Os efeitos da competição de N. physaloides e S. rhombifolia sobre as plantas de café foram os menores comparados aos causados pelas demais espécies de plantas daninhas, uma vez que apenas leves decréscimos – em todas as características avaliadas – no cafeeiro foram observados. As demais espécies de plantas daninhas causaram severa redução no crescimento do cafeeiro, principalmente com o incremento da densidade delas. O grau de interferência variou com a espécie e com a densidade das plantas daninhas. The effects of competition of seven weed species on the growth of coffee plants were evaluated under greenhouse conditions. Thirty days after coffee seedling transplantation into 12 L pots with soil level area of 6.5 dm2, weeds were transplanted into or sown in those pots, at densities of 0, 1, 2, 3, 4 and 5 plants per pot. Competition or weedy periods from weed transplantation or emergence to plant harvesting, at weed pre-flowering stage, were: 77 days - Bidens pilosa, 98 days - Brachiaria decumbens, 180 days - Commelina diffusa, 82 days - Leonurus sibiricus, 68 days - Nicandra physaloides, 148 days - Richardia brasiliensis and 133 days - Sida rhombifolia. Coffee plant height, stem diameter, leaf number and shoot dry matter were determined. Effects of competition by N. physaloides and S. rhombifolia against coffee plants were among the lowest, since only a slight decrease in all the characteristics evaluated in coffee plants was observed. The other weed species caused severe decrease in growth, mainly with increasing weed plant densities. Competition degree was found to depend on weed species and density.