psbA mutation (Ala251 to Val) in Chenopodium album resistant to triazinones

C

Raleio químico em pessegueiros 'BRS Kampai'

The objective of this work was to evaluate the effect of thinning with metamitron on the fruit yield and quality of 'BRS Kampai' peach (Prunus persica) trees. The experiment was carried out in the municipality of Eldorado do Sul, in the state of Rio Grande do Sul, Brazil, in the 2016 and 2017 crop years. Treatments consisted of the application of 100, 200, 300, and 400 mg L-1 metamitron and of hand thinning 40 days after full bloom, besides control plants. Fruit abscission, effective fructification, number of fruits, and fruit yield per plant were evaluated. Regarding fruit quality, fresh fruit biomass, epidermis color, pulp firmness, soluble solids, total phenolic compounds, and antioxidant activity were assessed; fruits were also classified into diameter classes. For fruit abscission, the effect of the application of 100 mg L-1 metamitron is similar to that of hand thinning. Fruit yield and mean mass in all treatments with metamitron are similar to those obtained by hand thinning. The application of metamitron does not affect the fruit quality of peach trees. Chemical thinning with metamitron may be an alternative to hand thinning in peach trees used for the production of fruits for fresh consumption.O objetivo deste trabalho foi avaliar o efeito do raleio com metamitron sobre a produção e a qualidade dos frutos de pessegueiros 'BRS Kampai' (Prunus persica). O experimento foi realizado no Município de Eldorado do Sul, no Estado do Rio Grande do Sul, durante as safras de 2016 e 2017. Os tratamentos consistiram na aplicação de 100, 200, 300 e 400 mg L-1 de metamitron e no raleio manual aos 40 dias após a plena floração, além de plantas-testemunhas. Foram avaliados abscisão de frutos, frutificação efetiva, número de frutos e produção de frutos por planta. Em relação à qualidade dos frutos, avaliaram-se biomassa fresca, coloração da epiderme, firmeza de polpa, sólidos solúveis, compostos fenólicos totais e atividade antioxidante; os frutos também foram classificados em classes de calibre. Quanto à abscisão de frutos, o efeito da aplicação de 100 mg L-1 de metamitron é similar ao do raleio manual. A produção e a massa média dos frutos em todos os tratamentos com metamitron são similares às obtidas com o raleio manual. A aplicação de metamitron não influencia a qualidade dos frutos de pessegueiros. O raleio químico com metamitron pode ser uma alternativa ao raleio manual em pessegueiros usados para produção de frutos para consumo fresco

Metamitron replacing carbaryl in post bloom thinning of apple trees.

Carbaryl or the mixture of carbaryl with NAA (naphthalene acetic acid) or BA (benzyladenine) are the post-bloom chemical thinners most widely used in apple thinning in Brazil. The marketing restriction of carbaryl demands new options of apple post-bloom thinners, requiring the evaluation of others compounds for this purpose. Metamitron is one of the substances that may be used in chemical thinning of apples. Metamitron was evaluated at two concentrations, alone or in mixture with BA, in "MaxiGala", "Fuji Suprema" and "Fred Hough" apple cultivars. Applications of metamitron at 384 mg L-1 and at 768 mg L-1 in a mixture with BA, ranging from 40 mg L-1 to 80 mg L-1, sprayed on fruits with diameter ranging from 5 to 25 mm were compared ith the standard treatment and hand thinning. The experimental design was a randomized complete block with 4-6 repetitions of a single plant. The variables analyzed were: fruit set (%); percentage of floral clusters with 1, 2, 3, 4 or more fruits; fruit yield (kg); verage fruit fresh mass (g) and percentage of dropped fruit after thinning. Metamitron alone or in combination with BA reduced production per plant and significantly increased the fresh weight of fruits in all cultivars tested. Metamitron at 800 mg L-1 resulted in excessive fruit thinning, especially in ?MaxiGala? cultivar. Metamitron or metamitron + BA have potential to compose the program of chemical thinning of apple trees to replace carbaryl. Index terms: Plant growth regulators, concentration, fruit set, fruit production. O carbaryl ou a mistura de carbaryl com ANA (ácido naftaleno acético) ou BA (Benziladenina) são os produtos mais utilizados no raleio químico da macieira no Brasil. Com o cancelamento do registro do carbaryl como raleante de pós-floração, são necessárias novas alternativas, sendo importante testar diferentes raleantes com esta finalidade. Dentre as substâncias passíveis de utilização no raleio da macieira insere-se o metamitron. O objetivo deste estudo foi avaliar a resposta da aplicação de metamitron no raleio das macieiras ?Fuji Suprema?, ?MaxiGala? e ?Fred Hough?. O uso de metamitron foi testado em duas concentrações, só ou em mistura de tanque com BA, e comparado com BA e BA + etefom, em três cultivares de macieira: ?Maxigala?, ?Fuji Suprema? e ?Fred Hough?. Aplicações de 384 mg L-1 e 768 mg L-1 de metamitron em mistura com BA de 40 mg L-1 e 80 mg L-1 aplicado em frutos de 5 a 25 mm de diâmetro foram comparadas com ?tratamento-padrão? e raleio manual. Foi usado o delineamento experimental em blocos ao acaso com cinco a seis repetições. As variáveis analisadas foram: frutificação efetiva (%), percentagem de cachos florais com 1; 2; 3; 4 ou mais frutos por inflorescência, produção por planta (kg), número de frutos por planta, massa média dos frutos (g) e percentagem de queda de frutos após o raleio. O metamitron só, ou em combinação com BA, reduziu a produção por planta e aumentou a massa média dos frutos em todas as cultivares estudadas. Metamitron a 768 mg L-1 resultou em excessivo raleio, especialmente na ?MaxiGala?. Metamitron ou metamitron + BA tem potencial para compor o programa de raleio químico da macieira em substituição ao carbaryl. Termos para indexação: Regulador de crescimento, concentração, frutificação efetiva, produção

Differential sensitivity of Atriplex patula and Chenopodium album to sugar beet herbicides : a possible cause for the upsurge of A. patula in sugar beet fields

In the last decade, the prevalence of Atriplex patula as a weed in the Belgian sugar beet area has increased. Possible reasons for its expansion in sugar beet fields, besides a poor implementation of the low-dose phenmedipham/activator/soil-acting herbicide (FAR) system, might be low sensitivity or evolved resistance to one or more herbicides used in sugar beet. Dose-response pot bioassays were conducted in the glasshouse to evaluate the effectiveness of five foliar-applied sugar beet herbicides (metamitron, phenmedipham, desmedipham, ethofumesate and triallate) and three pre-plant-incorporated herbicides (metamitron, lenacil, dimethenamid-P) for controlling five Belgian A.patula populations. Local metamitron-susceptible and metamitron-resistant populations of Chenopodium album were used as reference populations. Effective dosages and resistance indices were calculated. DNA sequence analysis of the photosystem II psbA gene was performed on putative resistant A.patula populations. Overall, A.patula exhibited large intraspecific variation in herbicide sensitivity. In general, A.patula populations were less susceptible to phenmedipham, desmedipham, ethofumesate and triallate relative to C.album populations. Two A.patula populations bear the leucine-218 to valine mutation on the chloroplast psbA gene conferring low level to high level cross-resistance to the photosystem II inhibitors phenmedipham, desmedipham, metamitron and lenacil. In order to avoid insufficient A.patula control and further spread, seedlings should preferentially be treated with FAR mixtures containing higher-than-standard doses of metamitron and phenmedipham/desmedipham and no later than the cotyledon stage

Effect of different application rates of metamitron as fruitlet chemical thinner on thinning efficacy and fluorescence inhibition in Gala and Fuji apple

Crop thinning is an important and difficult agricultural practice. Knowing the effect of the application dose of a product is a crucial element of any thinning program. The aims of this study were to investigate the effect of different metamitron doses on Gala and Fuji apples applied at fruit king diameters of between 8 and 10 mm and to determine fluorescence inhibition at the different application rates. Trials were conducted over two seasons from 2015 to 2016 in apple orchards in Lleida (Spain). Photosynthesis inhibition caused by metamitron was also analysed and measured, using chlorophyll fluorescence and biexponential pharmacokinetic models. Under the trial conditions, the application of metamitron reduced final fruit set, number of fruits per tree and crop load depending on the application rate. A dose effect was observed in all yield parameters. Moreover, when metamitron showed high efficacy, there was an improvement in fruit weight, coloration and diameter. The estimated parameters A, α and B using a biexponential equation were related with final fruit set, however the period of inhibition has to be finished before prediction can be made of metamitron efficacy in the year. The fluorescence analysis showed a dose effect, with metamitron dose increasing inhibition. Additionally, the same result was also observed in the area under curve analysis, with metamitron dose reducing the area and inhibition increasing. In all yield parameters, the fluorescence and area under curve analyses showed differences between cultivars, with the inhibition caused by metamitron higher in Gala than in Fuji. Moreover, differences between years were observed. 2015 was warmer than 2016, and the higher temperatures increased the thinning efficacy of metamitron.This study was supported financially by project INIA (RTA2012-00116-00-00) in collaboration with ADAMA-Spain

A comprehensive study of the effect of meteorological conditions on fruit abscission and metamitron thinning efficacy in Malus domestica Borkh

Doutoramento em Engenharia Agronómica / Instituto Superior de Agronomia. Universidade de LisboaMetamitron is an apple (Malus domestica Borkh.) fruit thinner that acts by reducing the photosynthetic capacity of trees. Thinning is a common practice among apple growers however, the effect of meteorological conditions, per si, and after metamitron spraying, is far from elucidated. In order to investigate the triggered physiological and biochemical processes, trials with shading nets (SN) during 5 days and high nighttime temperature (HNT) during 5 nights, along with high humidity (HH) for 3 h prior spraying were set in three locations, within 3 years. Lower irradiance caused a momentaneous photosynthetic decrease that led to reduced levels of leaf sucrose and sorbitol and consequent increases in fruit abscission rates. HNT pathway is a slight increment in the respiratory mechanisms, but mainly in the whole tree metabolic activity, finally resulting in a shortage in sucrose and sorbitol levels, reducing fruit growth and promoting higher abscission rates. Metamitron acts through a photosynthetic inhibition, including reductions in RuBisCO total activity, translating in less CH production. In addition, it stimulates vegetative growth, consuming CH and slowing down fruit growth rate, and finally enhancing of abscission. The combined treatments resulted in the strongest thinning efficacy, through a suppression of the CH production caused by metamitron in combination with low radiation and or through enhanced expenditure cause by HNT, frequently over-thinning. The effect of HH may enhance fruit drop under humid climates and in younger trees, more susceptible to variations in CH content. This work shows meteorological conditions, namely cloudy days, periods of HNT and increased humidity levels, may affect metamitron thinning efficacy and must be considered in order to decide which rate to apply to achieve an optimum crop loadN/

Time of metamitron application and concentration in the chemical thinning of "Maciel" peach.

Época e concentração do metamitron no raleio químico de pessegueiro "Maciel": No cultivo de pessegueiros o produtor tem o desafio de obter frutos de boa qualidade e manter a produção de forma equilibrada ao longo dos anos. O raleio favorece esses parâmetros e reduz a carga de frutos nas plantas. O raleio manual praticado comumente em pessegueiros, exige elevada mão de obra e onera os custos de produção. Estudos apontam o raleio químico como uma alternativa ao raleio manual, que dependendo da espécie, época e da dosagem empregada vem demonstrando eficiência nas frutíferas. O objetivo deste estudo foi avaliar o efeito do metamitron aplicado em diferentes épocas e concentrações no raleio químico de pessegueiros no Sul do Brasil. Experimentos foram conduzidos em pomar comercial de pessegueiro da cultivar Maciel, no município de Morro Redondo, Rio Grande do Sul, Brasil, durante as safras 2015 e 2016. No experimento 1 aplicou-se metamitron na concentração de 200 mg L-1 aos 20, 30, 40, 50 e 60 dias após a plena floração e raleio manual realizado aos 40 dias após a plena floração. No experimento 2 foram aplicados os tratamentos com metamitron nas concentrações de 100 mg L-1, 200 mg L-1, 300 mg L-1 e 400 mg L-1 e raleio manual realizados aos 40 dias após a plena floração, além das plantas testemunhas. Avaliou-se a abscisão dos frutos, frutificação efetiva, número total de frutos por planta, produção por planta, massa média e o diâmetro dos frutos. O metamitron na concentração de 200 mg L-1 possui efeito raleante quando aplicado antes dos 40 dias após a plena floração. A aplicação de 100 mg L-1 de metamitron aplicado 40 DAPF promoveu a abscisão de frutos superior ao raleio manual. Portanto, a aplicação de metamitron em pessegueiros "Maciel" mais próximo da plena floração, na concentração de 100 mg L-1 resulta numa pratica eficiente de raleio semelhante ao raleio manual

Fate of the organophosphate herbicide glyphosate in arable soils and its relationship to soil phosphorus status

Glyphosate is one of the world's most widely used herbicides. This study was undertaken to unravel the factors affecting its movement, sorption, persistence and leachability in different Finnish soils to create a sound basis for risk assessment. Field experiments indicated rather long persistence of glyphosate in Finnsih soils low in soil test P. The key soil factors promoting the persistence and reducing the leaching of glyphosate and its metabolite aminomethylphosphonic acid appeared to be low P status and high Al and Fe oxide contents in soil, leading to low degree of P saturation and to reduced biodegradability as result of strong sorption

Metamitron and Shade Effects on Leaf Physiology and Thinning Efficacy of Malus × domestica Borkh

Thinning strategies, namely shade or photosynthetic inhibitors, rely on the reduction of carbon supply to the fruit below the demand, causing fruit abscission. In order to clarify the subject, seven field trials were carried out in Lleida, Girona, and Sint-Truiden (2017 + 2018), using orchards of ‘Golden’ and ‘Gala’ apple trees. At the stage of 9–14-mm fruit diameter, four treatments were implemented: (A) CTR-control, trees under natural environmental conditions; (B) SN-shaded trees, trees above which shading nets reducing 50% of irradiance were installed 24 h after metamitron application date—without application of metamitron—and removed after five days; (C) MET-trees sprayed with 247.5 ppm of metamitron; (D) MET + SN-trees submitted to the combined exposure to metamitron application and shading nets. Low radiation significantly increased metamitron absorption (36–53% in the three locations in 2018) and reduced its degradation. Net photosynthesis and stomatal conductance were strongly reduced in all treatments, with minimum values 2 days after spraying (DAS) and incomplete recovery 10 DAS in MET + SN. All treatments resulted in leaf sucrose and sorbitol decreases, leading to a negative carbon balance. SN and MET + SN promoted the highest thinning efficacy, increasing fruit weight and size, with MET + SN causing over-thinning in some trials. Leaf antioxidant enzymes showed moderate changes in activity increases under MET or MET + SN, accompanied by a rise of glutathione content and a reduction in ascorbate, however without lipid peroxidation. This work shows that environmental conditions, such as cloudy days, must be carefully considered upon metamitron application, since the low irradiance enhances metamitron efficacy and may cause over-thinninginfo:eu-repo/semantics/publishedVersio