Name: protocols for robust herbicide resistance testing in different weed species
Uploaded: 2015-07-02T11:00:00.000+00:00
Duration: 10 min 52 s
Description: Watch this Scientific Journal Video about Protocols for Robust Herbicide Resistance Testing in Different Weed Species at JoVE.com

The research was supported by the National Research Council (CNR) of Italy. The authors thank GIRE members for collecting seed samples and are grateful to Alison Garside for revising the English.

1. As sementes de amostragem e armazenamento <ol><li> Monitorar campos cultivados para injustificada mau desempenho herbicida, ou seja, não devido a condições climáticas desfavoráveis ​​ou a tratamentos herbicidas de baixa qualidade. </li><li> Coletar uma amostra de sementes de uma espécie de cada vez e atribuir um código único. As sementes maduras são geralmente recolhidos antes da colheita das culturas de plantas que haviam sobrevivido ao tratamento (s) herbicida. Monitor de oportuna para observar se as sementes são derramadas por planta mãe quando maduro. </li><li> Preencher um formulário para cada amostra, indicando o código único atribuído, o nome da espécie, data da coleta, coordenadas GPS, município, nome do fazendeiro, tamanho do campo, nível de infestação, colheita, herbicida (s) utilizados durante a temporada e registros históricos do campo . </li><li> Coletar sementes de pelo menos 30 plantas selecionadas aleatoriamente, que sejam representativas da infestação campo. Certifique-se de que a amostra de sementes contém pelo menos 5.000 sementes maduras. Para um obrigatórios de cruzamento espécies de plantas daninhas(Por exemplo, Lolium spp. Ou Amaranthus spp.), Reduzir o número de plantas a 10-15, mantendo-se o número total de sementes em torno de 5000 11. </li><li> Sub-provar o campo se manchas de ervas daninhas estão espalhados em grandes áreas (mais de um hectare) como diferentes biótipos resistentes a herbicidas são selecionados. </li><li> Armazene sementes em sacos de papel sem lacre marcados com o código único atribuído. </li><li> Permitir que a umidade evapore, mas não exponha sementes a alta temperatura (isto é, evite deixá-los em um carro sob o sol) ou a flutuações extremas de temperatura para evitar a indução de dormência secundária. </li><li> Limpo (remover palha, sementes de-casco, etc.) e armazená-los à temperatura ambiente em um quarto seco. Após a realização dos testes de resistência primeiros, armazenar as sementes por longos períodos de tempo em um quarto escuro a 4 ° C, de preferência em selado a vácuo sacos de plástico. Em desta forma preservar a sua viabilidade das sementes por um tempo significativamente maior. </li></ol> NOTA: dormência das sementes fornece um mecanismo flexível e eficiente que permite que as ervas daninhas se adaptar e persistem em agro-ecossistemas. Para quebrar a dormência e permitir a germinação de sementes, protocolos diferentes têm de ser utilizados dependendo das espécies de ervas daninhas, isto é, o tipo de dormência 16. Existem três maneiras principais para remover dormência: <ol><li> Vernalização NOTA: Para obter germinação e emergência das plântulas em simultâneo, um período de vernalização semente que varia de alguns dias a uma semana é necessária para remover dormência fisiológica de muitas espécies.: Por exemplo, Amaranthus retroflexus, Chenopodium album, Lolium spp, Avena fátua, persicaria Polygonum , Phalaris paradoxa 17-19. É necessário um longo período de até 15 dias para rhoeas, difformis Cyperus e Ammania coccinea e até 30 dias para Schoenoplectus mucronatus <sup&gt; 20. <ol><li> Coloque um pouco de água deionizada em pratos de plástico. Corte duas camadas de papel de filtro e mergulhe-os em água, retire todo o excesso. Coloque as sementes secas ao ar no papel. Transferir as placas de plástico para um frigorífico a 4 ° C durante o período de tempo requerido. </li></ol></li><li> Escarificação NOTA: Algumas espécies de plantas daninhas são mais recalcitrante a germinação do que outros devido a dormência mecânica, ou seja, características do revestimento de semente, e exigir a utilização de uma escarificação química usando ácido sulfúrico a germinar 21. <ol><li> Prepara-se uma proveta com ácido sulfúrico concentrado (95-98%). Prepare um copo cheio de água. Coloque as sementes num envelope de tecido não-tecido. </li><li> Soak, por exemplo, Echinochloa spp. Sorghum halepense ou sementes durante 20 minutos ou 5 minutos, respectivamente, em ácido sulfúrico concentrado. </li><li> Pegue o envelope para fora do copo usando um par de pinças e colocá-lo no copo cheio de água. Abra oenvelope, coloque as sementes em um pequeno coador e lave-os com água corrente. </li></ol> Variante: A. plantago-aquatica precisa de um protocolo diferente de 22, 23 <ol><li> Embeber as sementes durante 2 min em clorofórmio. Lave as sementes com água deionizada e seque-os com papel absorvente. Húmido das sementes em ácido sulfúrico 80% durante 5 min. </li><li> Coloque as sementes em um pequeno coador e lave-os com água corrente. </li></ol></li><li> Maturação das sementes pós-colheita NOTA: Sementes de outras espécies de plantas daninhas não germinam em tudo por alguns meses após o vencimento, independentemente do método utilizado para quebrar a dormência. <ol><li> Armazenar as sementes por um período de, pelo menos, 3-4 meses à temperatura ambiente e baixa umidade e siga os protocolos acima para quebra de dormência (por exemplo, Oryza sativa var. Sylvatica ou P. rhoeas). </li></ol></li></ol> A germinação 3. Semente <ol><li> Coloque as sementes de ser germinadas em plastic pratos contendo 0,6% (v / m) de ágar com nitrato de potássio a 0,1% (KNO 3) adicionado: <ol><li> Prepara-se uma solução de agar a 0,6% + 0,1% de KNO 3 usando água desionizada. Dissolve-se o ágar em um forno de microondas. </li><li> Despeje a solução agar em pratos de plástico. Arrefecer o substrato e, em seguida, colocar nas sementes. </li></ol> Variante: O solo pode também ser utilizado como um substrato em pratos de plástico. Esta prática é particularmente eficiente para Echinochloa spp., S. halepense e Lolium spp. </li><li> Coloque pratos de plástico em uma câmara de germinação por cerca de uma semana com luz e temperatura condições, dependendo das condições óptimas para cada espécie de erva daninha. Para a maioria das espécies de inverno, a temperatura é 15/25 ° C dia / noite e 12 horas de fotoperíodo com tubos de néon proporcionando uma densidade de fluxo de fótons fotossintéticos (DFFF) de 15-30 mol m -2 s -1. Para muitas espécies de verão, a gama de temperaturas é de 15/30 ° C dia / noite. Variante: Some espécies, tais como S. halepense, precisa de um tratamento térmico. Portanto, após a escarificação, as sementes de S. halepense são submetidos às seguintes condições: ciclos de 4 horas a 45 ° C e 20 h a 24 ° C durante três dias no gabinete de germinação, e, em seguida, três dias em condições normais. </li></ol> 4. das mudas e Crescimento <ol><li> Transplante de quinze a vinte mudas em bandejas plásticas (325 x 265 x 95 mm) carregada com uma mistura padrão de envasamento (60% solo franco silty, 15% de areia, 15% e 10% agriperlite turfa - por volume). NOTA: O transplante, em vez de sementeira directa, permite um suporte uniforme de plantas, na mesma fase de crescimento a ser obtido, que é um importante pré-requisito para optimizar o rendimento do tratamento com herbicida. </li><li> Identificar cada bandeja com um código de barras, incluindo todas as informações para a identificação única: Código população, herbicida que está sendo testado, replicar número e número da bandeja progressiva &lt;./ Li&gt; <li> Coloque as bandejas em uma aquecida com efeito de estufa e água plantas como necessários para manter o substrato em ou perto de capacidade de campo. NOTA: A temperatura de crescimento varia dependendo das espécies de ervas daninhas. Muitas vezes, os testes são feitos durante o outono / inverno / primavera, para que a luz é completada utilizando lâmpadas de 400 W halógenas, que fornecem uma PPFD de cerca de 150 mol m -2 s -1 e fotoperíodo de 12 h 24, 19 espécies de plantas daninhas. Verão com C 4 ciclo fotossintético geralmente exigem maior intensidade de luz e, portanto, os testes são feitos no final de primavera-verão ou a intensidade da luz é completada cerca de 400 mol m -2 s -1 com um fotoperíodo de 14 horas. </li><li> Use um protocolo diferente para algumas espécies de plantas daninhas que infestam o arroz em casca, por exemplo, A. plantago-aquatica, S. mucronatus e C. difformis, tal como descrito em 22. <ol><li> Transplante as mudas em bandejas de poliestireno com 24 células redondas (55 mm de diâmetro, 64 mm de profundidade) filliderou com 60% solo franco silty, 30% de areia e 10% de turfa (em volume). </li><li> Definir as bandejas 12 centímetros em recipientes de plástico cheios de água profundas e battened para baixo por hastes de aço inoxidável para impedi-los aparafusadas flutuante (Figura 1). </li><li> Manter o nível de água nos recipientes em 1-2 cm abaixo do nível da superfície do solo e adicionar 1,5 g de sulfato de cobre para cada recipiente (que contém 10-12 L de água) para evitar a proliferação de algas. </li></ol></li></ol> 5. tratamentos herbicidas <ol><li> Os tratamentos com herbicidas pré-emergentes: <ol><li> Após cerca de três dias na câmara de germinação, conforme descrito na seção 3, transplantar as sementes germinam em bandejas plásticas contendo substrato descrito acima e cubra com uma camada de solo (cerca de 1 cm). Este é um passo crítico para assegurar que as plantas não vão emergir devido ao efeito herbicida em vez de uma profundidade de enterramento excessiva. </li><li> Leve o substrato para o campo capacidade, colocando os tabuleiros, que têm alguns furos na parte inferior, sobre discos cheios de água. </li><li> Um dia após o transplante, tratar as bandejas com o herbicida pré-emergência 25. </li><li> Manter o substrato na ou perto da capacidade de campo por adição de água conforme necessário, tanto a partir de cima e abaixo, por capilaridade a partir do disco. Este procedimento favorece a permanência do herbicida na profundidade apropriada (isto é, onde as sementes em germinação são) para uma boa eficácia do tratamento. </li></ol></li><li> Os tratamentos com herbicidas pós-emergentes: <ol><li> Spray de plantas quando atingem a fase de 2-3 folhas (isto é, fase de crescimento 12-13 da escala de crescimento BBCH estendida 26). </li><li> A partir do dia após o tratamento, defina o sistema de irrigação de acordo com as necessidades de água das espécies de plantas daninhas e da época (por exemplo, para Echinochloa spp. Que fornece água para 3 min 4 vezes por dia, em intervalos regulares, das 9 horas às 9 pm). A água é disbuído usando um sistema de irrigação por aspersão automática. Variante: glifosato é aplicada na planta fase BBCH 14-21. </li></ol></li><li> Preparação herbicida e distribuição. NOTA: Todos os herbicidas (pré e pós-emergência) são aplicadas como formulações comerciais com surfactantes recomendadas em duas doses, dose recomendada campo (1x) e três vezes que (3x). <ol><li> Se necessário, preparar a solução de agente tensioactivo em massa de acordo com as instruções do rótulo; a concentração final é normalmente expresso como uma percentagem do volume final (por exemplo, 0,3%) ou como o volume a ser distribuído por unidade de área (por exemplo, 1 L ha -1). </li><li> Utilizar a solução de agente tensioactivo, como solvente para a solução de herbicida (soluto) de modo a manter a concentração correcta do ingrediente activo. Preparar a solução herbicida mais concentrada primeiro (3x). Calcular a quantidade do produto comercial para ser dissolvido na solução de agente tensioactivo (ou em água desionizada se umtensioactivo não é necessário) usando a seguinte equação: Dose erva = [(Dose Dose campo x max) x V aleta] / V del Onde: Dose erva = dose de herbicida (ml), de dose Dose campo = campo herbicida (ml ha -1), Dose Max = dose máxima entregue, V fin = volume final da solução (l), V del = volume entregue pela Pulverizador banco (L ha -1). </li><li> Diluir (2: 1, v / v) a solução 3x herbicida para preparar o menos concentrada (1x). Este procedimento reduz a chance de cometer erros quando pesagem ou pipetando os herbicidas. Concentração da solução herbicida é expressa como o volume a ser distribuído por unidade de área (L ha -1). </li><li> Iniciar a sequência de tratamento com a dose de herbicida inferior (1x). Desta forma não há necessidade de lavar o armário de pulverização entre dois tratamentos com o mesmo herbicida. </li><li> Distribua o solutio herbicidan, usando um pulverizador de banco precisão entregar 300 L ha -1 (± 1%), a uma pressão de 215 kPa e uma velocidade de 0,75 m seg-1, com um braço equipado com três ventoinha plana (faixa estendida) bicos hidráulicos . </li><li> Lave o gabinete de pulverização duas vezes quando o herbicida é alterada utilizando água sanitária 1% (v / v) e depois enxaguar. Variante: glifosato é aplicado com um volume de calda de 200 L ha -1 27. NOTA: Particular atenção tem de ser pago quando herbicidas altamente biológicos, como o sulfometuron sulfoniluréias ou flazasulfuron, são usados. Neste último caso, fazer uma lavagem com uma solução alcalina e um outro com amónia (2,5% v / v), seguido de uma lavagem cuidadosa com água. </li></ol></li></ol> 6. Coleta e análise dos dados <ol><li> Através de um leitor de código de barras, que identifica automaticamente cada bandeja, gravar o número de plantas que sobreviveram ao tratamento, bem como a biomassa Visual estimado (VEB). As plantas são assEssed como sendo mortos se eles não mostram o crescimento ativo independentemente da cor ou outra aparência. <ol><li> Faça a avaliação de três ou quatro semanas após o tratamento (WAT), dependendo dos herbicidas testados (por exemplo, três WAT para os inibidores de ACCase e quatro WAT para os inibidores de ALS ou glifosato). </li><li> Avaliar a eficácia do tratamento geral, incluindo uma população suscetível (verifique S) em todos os experimentos, ou seja, uma população coletada em um site que nunca ou raramente tratado com herbicidas era. </li><li> Expresso de sobrevivência das plantas, como percentagem do número de plantas tratadas, contado imediatamente antes do tratamento herbicida, e calcular o erro padrão (EP) por valor médio (valor das duas repetições média). </li><li> O VEB é obtido através de uma comparação visual de biomassa vegetal entre tratados e não-tratados de verificação da mesma população 25, 28. Um escore, variando de 10 para as plantas não afetadas pelo herbicida (em comparação com o check-tratados não) para 0 quandoas plantas são claramente morta, é dada a cada bandeja tratada. </li></ol></li><li> Populações atribuir a quatro categorias com base nos resultados obtidos a partir dos tratamentos com duas doses de herbicida: S, quando menos do que 5% das plantas sobreviveram os 1x dose do herbicida, quando SR sobreviventes variou de 5% a 20% em 1x dose do herbicida, quando mais do que R 20% das plantas sobreviveram os 1x dose do herbicida e RR sobreviventes quando são mais do que 20% na dose de herbicida 1x e mais do que 10% na dose de herbicida 3x 17. </li></ol>

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Weeds. , 783-790 (1999).</li><li>Scarabel, L., Berto, D., Sattin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dormancy+breaking+and+germination+of+Alisma+plantago-aquatica.+and+Scirpus+mucronatus.">Dormancy breaking and germination of Alisma plantago-aquatica. and Scirpus mucronatus.</a> Aspects of Applied Biology. 69, 285-292 (2003).</li><li>Collavo, A., Strek, H., Beffa, R., Sattin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Management+of+an+ACCase-inhibitor-resistant+Lolium+rigidum.+population+based+on+the+use+of+ALS+inhibitors:+weed+population+evolution+observed+over+a+7+years+field-scale+investigation.">Management of an ACCase-inhibitor-resistant Lolium rigidum. population based on the use of ALS inhibitors: weed population evolution observed over a 7 years field-scale investigation.</a> Pest Manag. Sci. 69 (2), 200-208 (2013).</li><li>Scarabel, L., Panozzo, S., Savoia, W., Sattin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Target-site+ACCase-resistant+Johnsongrass+(Sorghum+halepense).+selected+in+summer+dicot+crops.">Target-site ACCase-resistant Johnsongrass (Sorghum halepense). selected in summer dicot crops.</a> Weed Technol. 28 (2), 307-315 (2014).</li><li>Hess, M., Barralis, H., Bleiholder, H., Buhur, L., Eggers, T., Hack, H., Strauss, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+the+extended+BBCH+scale+-+general+for+the+description+of+the+growth+stages+of+mono-+and+dicotyledonous+weed+species.">Use of the extended BBCH scale - general for the description of the growth stages of mono- and dicotyledonous weed species.</a> Weed Res. 37 (6), 433-441 (1997).</li><li>Collavo, A., Sattin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=First+glyphosate-resistant+Lolium.+spp.+biotypes+found+in+a+European+annual+arable+cropping+system+also+affected+by+ACCase+and+ALS+resistance.">First glyphosate-resistant Lolium. spp. biotypes found in a European annual arable cropping system also affected by ACCase and ALS resistance.</a> Weed Res. 54 (4), 325-334 (2014).</li><li>Scarabel, L., Cenghialta, C., Manuello, D., Sattin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monitoring+and+management+of+imidazolinone-resistant+red+rice+(Oryza+sativa.+L.,+var.+sylvatica.)+in+Clearfield&#174;+Italian+paddy+rice.">Monitoring and management of imidazolinone-resistant red rice (Oryza sativa. L., var. sylvatica.) in Clearfield&#174; Italian paddy rice.</a> Agronomy. 2 (4), 371-383 (2012).</li><li>Zelaya, I. A., Anderson, J. A. H., Owen, M. D. K., Landes, R. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+spectrophotometric+and+HPLC+methods+for+shikimic+acid+determination+in+plants:+Models+in+glyphosate-resistant+and-susceptible+crops.">Evaluation of spectrophotometric and HPLC methods for shikimic acid determination in plants: Models in glyphosate-resistant and-susceptible crops.</a> J. Agric. Food Chem. 59 (6), 2202-2212 (2011).</li></ol>

The authors declare that they have no competing financial interests.

Várias medidas no âmbito dos protocolos são críticos para uma avaliação bem sucedida de resistência a herbicidas em uma população: 1) sementes devem ser coletadas quando madura a partir de plantas que sobreviveram ao tratamento (s) herbicida. Maturação das sementes na planta mãe é crucial para evitar dificuldades na germinação das sementes mais tarde; 2) É recomendado o armazenamento adequado das sementes para evitar a proliferação de fungos que possam impedir a germinação; 3) mudas devem ser tratada...

<html> Os herbicidas são a medida controle de plantas daninhas mais amplamente utilizado, sendo responsável por até 50% do mercado global de proteção de plantas 1. Eles são ferramentas relativamente baratas, evitar práticas de cultivo do solo e demorado de trabalho intensivo, e, finalmente, resultar na produção de custo-eficaz, segura e rentável comida 2. No entanto, a grande variabilidade genética fenológico e presente em muitas espécies de plantas daninhas, em conjunto com um excesso de confiança no uso de herbicidas, freqüentemente resulta na seleção de populações de plantas daninhas resistentes a herbicidas. A introdução de herbicidas selectivos com um alvo metabólica muito específico 3-5 aumentou dramaticamente o número de casos de resistência ao longo dos anos. Até o momento, 240 espécies de plantas daninhas dicotiledôneas (140 e 100 monocotiledôneas) no mundo todo desenvolveram resistência a diferentes herbicidas Sites de Ação (SoA) 4. Esta é uma grande preocupação para manejo de plantas daninhas e mais em geral, para a produção agrícola sustentável. e_content &quot;&gt; A detecção precoce da resistência, com base em testes confiáveis, freqüentemente realizados em casa de vegetação, é um passo fundamental para manejo de ervas daninhas resistentes a herbicidas. Diferentes abordagens têm sido desenvolvidas de acordo com os objectivos, necessário nível de precisão, o tempo e os recursos disponíveis, como bem como as espécies de ervas daninhas considerados 12/06. No entanto, quando é requerida a confirmação do estado de resistência de um novo biótipo de ervas daninhas (isto é, um grupo de indivíduos que partilham várias características fisiológicas, incluindo a capacidade de sobreviver a um ou mais herbicidas pertencentes a um grupo particular utilizado a uma dose que normalmente controlá-los), uma planta inteira robusta bioensaio tem de ser realizada num ambiente controlado, 4, 11. Um biótipo raramente é resistente a apenas um herbicida. Cada biótipo é, portanto, caracterizada por um determinado padrão de resistência, isto é, o número e tipo de SOA dos herbicidas é resistente a, e por uma dada resistêncianível de cada herbicida 13. A determinação precoce e confiável do padrão de cruz ou resistência múltipla 5, 14 é importante para o manejo da resistência de campo. Vale ressaltar que a resistência a herbicidas tem nada a ver com a tolerância natural que algumas exposições de plantas daninhas em relação a alguns herbicidas, por exemplo, espécies dicot vs. herbicidas inibidores da ACCase, espécies monocotiledôneas vs. 2,4-D, Equisetum arvense vs. glifosato. Este artigo apresenta uma abordagem robusta para testar biótipos resistentes a herbicidas putativo amostradas em campos onde mau controle por herbicida (s) haviam sido relatados. Variantes relevantes para os protocolos padrão em relação às espécies de plantas daninhas envolvidos são apresentados. As vantagens sobre as técnicas alternativas / protocolos baseados em inteiros quer bioensaios vegetais utilizando apenas uma dose de herbicida 15, ou o tratamento de sementes em placas de Petri de 8 estão relacionados com a maior reliability e inferir a possibilidade de o nível de resistência devido à inclusão de duas doses do herbicida nas experiências. No entanto, para o teste de resistência de rotina, os mesmos métodos podem ser aplicados no apenas uma dose do herbicida, assim reduzindo os custos. Bem como permitindo a confirmação do estado de resistência, a informação obtida pode ser usada para optimizar tanto as seguintes etapas de pesquisa e / ou a concepção de estratégias de gestão da resistência de som.

<table><tbody><tr><td>Paper bags</td><td>Celcar SAS</td><td></td><td></td></tr><tr><td>Plastic dishes</td><td>ISI plast S.p.A.</td><td>SO600</td><td>Transparent plastic</td></tr><tr><td>Sulfuric acid 95-98%</td><td>Sigma-Aldrich</td><td>320501</td><td></td></tr><tr><td>Non-woven fabric</td><td>Carretta Tessitura</td><td>Art.TNT17</td><td>Weight 17 g m&lt;sup&gt;-2&lt;/sup&gt;</td></tr><tr><td>Chloroform &gt;99.5%</td><td>Sigma-Aldrich</td><td>C2432</td><td></td></tr><tr><td>Agar</td><td>Sigma-Aldrich</td><td>A1296</td><td></td></tr><tr><td>Potassium nitrate &gt;99.0%</td><td>Sigma-Aldrich</td><td>P8394</td><td></td></tr><tr><td>Plastic containers</td><td>Giganplast</td><td>1875/M</td><td>600 x 400 x 110 mm</td></tr><tr><td>Plastic trays</td><td>Piber plast</td><td>G1210A</td><td>325 x 265 x 95 mm</td></tr><tr><td>Polystyrene trays</td><td>Plastisavio</td><td>S24</td><td>537 x 328 x 72 mm, 24 round cells (6x4)</td></tr><tr><td>Copper sulfate</td><td>Sigma-Aldrich</td><td>451657</td><td></td></tr><tr><td>Agriperlite</td><td>Blu Agroingross sas</td><td>AGRI100</td><td></td></tr><tr><td>Peat</td><td>Blu Agroingross sas</td><td>TORBA250</td><td></td></tr><tr><td>Germination cabinet</td><td>KW</td><td>W87R</td><td></td></tr><tr><td>Nozzles</td><td>Teejet</td><td>XR11002-VK, TP11001-VH</td><td>The second type of nozzles are used only for glyphosate</td></tr><tr><td>Barcode generator</td><td>Toshiba TEC</td><td>SX4</td><td></td></tr><tr><td>Labels with barcode</td><td>Felga</td><td>TT20200</td><td>Stick-in labels with rounded corners</td></tr><tr><td>Barcode reader</td><td>Cipherlab</td><td>8300-L</td><td>Portable data terminal</td></tr><tr><td>Bench sprayer</td><td></td><td></td><td>Built in house</td></tr><tr><td colspan="4">&lt;strong&gt;Herbicides included in the results:&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;Commercial product&lt;/strong&gt;</td><td>&lt;strong&gt;Active ingredient&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>Altorex</td><td>imazamox</td><td>BASF</td><td></td></tr><tr><td>Azimut</td><td>florasulam</td><td>Dow AgroSciences</td><td></td></tr><tr><td>Biopower</td><td></td><td>Bayer Crop Science</td><td>Surfact to be used with Hussar WG</td></tr><tr><td>Dash</td><td></td><td>BASF</td><td>Surfact to be used with Altorex</td></tr><tr><td>Granstar</td><td>tribenuron-methyl</td><td>Dupont</td><td></td></tr><tr><td>Gulliver</td><td>azimsulfuron</td><td>Dupont</td><td></td></tr><tr><td>Hussar WG</td><td>iodosulfuron</td><td>Bayer Crop Science</td><td></td></tr><tr><td>Nominee</td><td>bispyribac-Na</td><td>Bayer Crop Science</td><td></td></tr><tr><td>Roundup</td><td>glyphosate</td><td>Monsanto</td><td></td></tr><tr><td>Trend</td><td></td><td>Dupont</td><td>Surfact to be used with Granstar and Gulliver</td></tr><tr><td>Viper</td><td>penoxsulam</td><td>Dow AgroSciences</td><td></td></tr><tr><td>Weedone LV4</td><td>2,4-D</td><td>Isagro</td><td></td></tr></tbody></table>

protocols for robust herbicide resistance testing in different weed species

Robust protocols to test putative herbicide resistant weed populations at whole plant level are essential to confirm the resistance status. The presented protocols, based on whole-plant bioassays performed in a greenhouse, can be readily adapted to a wide range of weed species and herbicides through appropriate variants. Seed samples from plants that survived a field herbicide treatment are collected and stored dry at low temperature until used. Germination methods differ according to weed species and seed dormancy type. Seedlings at similar growth stage are transplanted and maintained in the greenhouse under appropriate conditions until plants have reached the right growth stage for herbicide treatment. Accuracy is required to prepare the herbicide solution to avoid unverifiable mistakes. Other critical steps such as the application volume and spray speed are also evaluated. The advantages of this protocol, compared to others based on whole plant bioassays using one herbicide dose, are related to the higher reliability and the possibility of inferring the resistance level. Quicker and less expensive in vivo or in vitro diagnostic screening tests have been proposed (Petri dish bioassays, spectrophotometric tests), but they provide only qualitative information and their widespread use is hindered by the laborious set-up that some species may require. For routine resistance testing, the proposed whole plant bioassay can be applied at only one herbicide dose, so reducing the costs.

Para avaliar o estado de resistência de uma população resistente putativo, é fundamental para incluir um controlo susceptível no ensaio, a fim de verificar a eficácia do herbicida. Os resultados de um teste de rastreio realizados em P. populações rhoeas, uma erva daninha infestante campos de trigo, são relatados na Figura 2, onde a eficácia de quatro herbicidas em pós-emergência sobre um cheque suscetível (09-36) e sobre a suspeita de um resistente (10-91) são apresentado...

Watch this Scientific Journal Video about Protocols for Robust Herbicide Resistance Testing in Different Weed Species at JoVE.com

Protocols for Robust Herbicide Resistance Testing in Different Weed Species

A robust and flexible approach to confirm herbicide resistance in weed populations is presented. This protocol allows the herbicide resistance levels to be inferred and applied to a wide range of weed species and herbicides with minor adaptations.

Protocolos para Robust Teste de resistência a herbicidas em diferentes espécies de plantas daninhas

Robust protocols to test putative herbicide resistant weed populations at whole plant level are essential to confirm the resistance status. The presented ...

protocols-for-robust-herbicide-resistance-testing-different-weed

Universidad San Sebastian

Research

JoVE Journal

Environment

14.5K visualizações.  National Research Council (CNR), Italy. A robust and flexible approach to confirm herbicide resistance in weed populations is presented. This protocol allows the herbicide resistance levels to be inferred and applied to a wide range of weed species and herbicides with minor adaptations.

Vídeo: Protocols for Robust Herbicide Resistance Testing in Different Weed Species

Genetic Manipulation of the Plant Pathogen Ustilago maydis to Study Fungal Biology and Plant Microbe Interactions

Gene deletion plays an important role in the analysis of gene function. One of the most efficient methods to disrupt genes in a targeted manner is the replacement of the entire gene with a selectable marker via homologous recombination. During homologous recombination, exchange of DNA takes place between sequences with high similarity. Therefore, linear genomic sequences flanking a target gene can be used to specifically direct a selectable marker to the desired integration site. Blunt ends of the deletion construct activate the cell&#39;s DNA repair systems and thereby promote integration of the construct either via homologous recombination or by non-homologous-end-joining. In organisms with efficient homologous recombination, the rate of successful gene deletion can reach more than 50% making this strategy a valuable gene disruption system. The smut fungus Ustilago maydis is a eukaryotic model microorganism showing such efficient homologous recombination. Out of its about 6,900 genes, many have been functionally characterized with the help of deletion mutants, and repeated failure of gene replacement attempts points at essential function of the gene. Subsequent characterization of the gene function by tagging with fluorescent markers or mutations of predicted domains also relies on DNA exchange via homologous recombination. Here, we present the U. maydis strain generation strategy in detail using the simplest example, the gene deletion.

Genetic Manipulation of the Plant Pathogen Ustilago maydis to Study Fungal Biology and Plant Microbe Interactions

We describe a robust gene replacement strategy to genetically manipulate the smut fungus Ustilago maydis. This protocol explains how to generate deletion mutants to investigate infection phenotypes. It can be extended to modify genes in any desired way, e.g., by adding a sequence encoding a fluorescent protein tag.

Manipulação genética do patógeno de planta<em&gt; Ustilago maydis</em&gt; Estudar Biologia fúngicos e vegetais Microbe Interactions

Gene deletion plays an important role in the analysis of gene function. One of the most efficient methods to disrupt genes in a targeted manner is the ...

Genética

Measuring Rates of Herbicide Metabolism in Dicot Weeds with an Excised Leaf Assay

In order to isolate and accurately determine rates of herbicide metabolism in an obligate-outcrossing dicot weed, waterhemp (Amaranthus tuberculatus), we developed an excised leaf assay combined with a vegetative cloning strategy to normalize herbicide uptake and remove translocation as contributing factors in herbicide-resistant (R) and &#8211;sensitive (S) waterhemp populations. Biokinetic analyses of organic pesticides in plants typically include the determination of uptake, translocation (delivery to the target site), metabolic fate, and interactions with the target site. Herbicide metabolism is an important parameter to measure in herbicide-resistant weeds and herbicide-tolerant crops, and is typically accomplished with whole-plant tests using radiolabeled herbicides. However, one difficulty with interpreting biokinetic parameters derived from whole-plant methods is that translocation is often affected by rates of herbicide metabolism, since polar metabolites are usually not mobile within the plant following herbicide detoxification reactions. Advantages of the protocol described in this manuscript include reproducible, accurate, and rapid determination of herbicide degradation rates in R and S populations, a substantial decrease in the amount of radiolabeled herbicide consumed, a large reduction in radiolabeled plant materials requiring further handling and disposal, and the ability to perform radiolabeled herbicide experiments in the lab or growth chamber instead of a greenhouse. As herbicide resistance continues to develop and spread in dicot weed populations worldwide, the excised leaf assay method developed and described herein will provide an invaluable technique for investigating non-target site-based resistance due to enhanced rates of herbicide metabolism and detoxification.

This manuscript describes how herbicide metabolism rates can be effectively quantified with excised leaves from a dicot weed, thereby reducing variability and removing any possible confounding effects of herbicide uptake or translocation typically observed in whole-plant assays.

Medindo Taxas de Herbicida Metabolismo em Dicot Weeds com um ensaio extirpado Folha

In order to isolate and accurately determine rates of herbicide metabolism in an obligate-outcrossing dicot weed, waterhemp (Amaranthus tuberculatus), we ...

Ambiente

Protocols for Quantifying Transferable Pesticide Residues in Turfgrass Systems

Plant canopies in established turfgrass systems can intercept an appreciable amount of sprayed pesticides, which can be transferred through various routes onto humans. For this reason, transferable pesticide residue experiments are required for registration and re-registration by the United States Environmental Protection Agency (USEPA). Although such experiments are required, limited specificity is required pertaining to experimental approach. Experimental approaches used to assess pesticide transfer to humans including hand wiping with cotton gloves, modified California roller (moving a roller of known mass over cotton cloth) and soccer ball roll (ball wrapped with sorbent strip) over three treated turfgrass species (creeping bentgrass, hybrid bermudagrass and tall fescue maintained at 0.4, 5 and 9 cm, respectively) are presented. The modified California roller is the most extensively utilized approach to date, and is best suited for use at low mowing heights due to its reproducibility and large sampling area. The soccer ball roll is a less aggressive transfer approach; however, it mimics a very common occurrence in the most popular international sport, and has many implications for nondietary pesticide exposure from hand-to-mouth contact. Additionally, this approach may be adjusted for other athletic activities with limited modification. Hand wiping is the best approach to transfer pesticides at higher mowing heights, as roller-based approaches can lay blades over; however, it is more subjective due to more variable sampling pressure. Utility of these methods across turfgrass species is presented, and additional considerations to conduct transferable pesticide residue research in turfgrass systems are discussed.

Transferable pesticide residue experiments in turfgrass systems are integral components of human risk exposure assessments. Experimental approaches to measure transferable residues should be adjusted to the human interaction of interest and turfgrass system dynamics. Three transferable pesticide residue protocols are presented and the suitability across three turfgrass systems is discussed.

Protocolos para quantificar os resíduos de pesticidas transferíveis em Sistemas de relva

Plant canopies in established turfgrass systems can intercept an appreciable amount of sprayed pesticides, which can be transferred through various routes ...

Screening Cotton Genotypes for Reniform Nematode Resistance

A rapid non-destructive reniform nematode (Rotylenchulus reniformis) screening protocol is needed for the development of resistant cotton (Gossypium hirsutum) varieties to improve nematode management. Most protocols involve extracting vermiform nematodes or eggs from the cotton root system or potting soil to determine population density or reproduction rate. These approaches are generally time-consuming with a small number of genotypes evaluated. An alternative approach is described here in which the root system is visually examined for nematode infection. The protocol involves inoculating cotton seedling 7 days after planting with vermiform nematodes and determining the number of females attached to the root system 28 days after inoculation. Data are expressed as the number of females per gram of fresh root weight to adjust for variation in root growth. The protocol provides an excellent method for evaluating host-plant resistance associated with the ability of the nematode to establish an infection site; however, resistance that hinders nematode reproduction is not assessed. As with other screening protocols, variation is commonly observed in nematode infection among individual genotypes within and between experiments. Data are presented to illustrate the range of variation observed using the protocol. To adjust for this variation, control genotypes are included in experiments. Nonetheless, the protocol provides a simple and rapid method to evaluate host-plant resistance. The protocol has been successfully used to identify resistant accessions from the G. arboreum germplasm collection and evaluate segregating populations of more than 300 individuals to determine the genetics of resistance. A vegetative propagation method for recovering plants for resistance breeding was also developed. After removal of the root system for nematode evaluation, the vegetative shoot is replanted to allow the development of a new root system. More than 95% of the shoots typically develop a new root system with plants reaching maturity.

Here, a protocol is presented for the rapid non-destructive screening of cotton genotypes for reniform nematode resistance. The protocol involves visually examining the roots of nematode-infected cotton seedlings to determine infection response. The vegetative shoot from each plant is then propagated to recover plants for seed production.

Triagem de genótipos de algodão para resistência ao nematódeo reniforme

A rapid non-destructive reniform nematode (Rotylenchulus reniformis) screening protocol is needed for the development of resistant cotton (Gossypium ...

Quantification of the Potential Impact of Glyphosate-Based Products on Microbiomes

Glyphosate-based products (GBP) are the most common broad-spectrum herbicides worldwide. The target of glyphosate is the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) in the shikimate pathway, which is virtually universal in plants. The inhibition of the enzyme stops the production of three essential amino acids: phenylalanine, tyrosine, and tryptophan. EPSPS is also present in fungi and prokaryotes, such as archaea and bacteria; thus, the use of GBP may have an impact on the microbiome composition of soils, plants, herbivores, and secondary consumers. This article aims to present general guidelines to assess the effect of GBP on microbiomes from field experiments to bioinformatics analyses and provide a few testable hypotheses. Two field experiments are presented to test the GBP on non-target organisms. First, plant-associated microbes from 10 replicated control and GBP treatment plots simulating no-till cropping are sampled and analyzed. In the second experiment, samples from experimental plots fertilized by either poultry manure containing glyphosate residues or non-treated control manure were obtained. Bioinformatics analysis of EPSPS protein sequences is utilized to determine the potential sensitivity of microbes to glyphosate. The first step in estimating the effect of GBP on microbiomes is to determine their potential sensitivity to the target enzyme (EPSPS). Microbial sequences can be obtained either from public repositories or by means of PCR amplification. However, in the majority of field studies, microbiome composition has been determined based on universal DNA markers such as the 16S rRNA and the internal transcribed spacer (ITS). In these cases, sensitivity to glyphosate can only be estimated through a probabilistic analysis of EPSPS sequences using closely related species. The quantification of the potential sensitivity of organisms to glyphosate, based on the EPSPS enzyme, provides a robust approach for further experiments to study target and non-target resistant mechanisms.

Glyphosate-based products (GBP) are the most common broad-spectrum herbicides worldwide. In this article, we introduce general guidelines to quantify the effect of GBP on microbiomes, from field experiments to bioinformatics analyses.

Quantificação do impacto potencial dos produtos à base de glifosato em microbiomas

Glyphosate-based products (GBP) are the most common broad-spectrum herbicides worldwide. The target of glyphosate is the enzyme ...

Bioassays for Monitoring Insecticide Resistance

Pest resistance to pesticides is an increasing problem because pesticides are an integral part of high-yielding production agriculture. When few products are labeled for an individual pest within a particular crop system, chemical control options are limited. Therefore, the same product(s) are used repeatedly and continual selection pressure is placed on the target pest. There are both financial and environmental costs associated with the development of resistant populations. The cost of pesticide resistance has been estimated at approximately $ 1.5 billion annually in the United States. This paper will describe protocols, currently used to monitor arthropod (specifically insects) populations for the development of resistance. The adult vial test is used to measure the toxicity to contact insecticides and a modification of this test is used for plant-systemic insecticides. In these bioassays, insects are exposed to technical grade insecticide and responses (mortality) recorded at a specific post-exposure interval. The mortality data are subjected to Log Dose probit analysis to generate estimates of a lethal concentration that provides mortality to 50% (LC50) of the target populations and a series of confidence limits (CL's) as estimates of data variability. When these data are collected for a range of insecticide-susceptible populations, the LC50 can be used as baseline data for future monitoring purposes. After populations have been exposed to products, the results can be compared to a previously determined LC50 using the same methodology.

This manuscript demonstrates and discusses techniques used to survey pesticide susceptibility and detect resistance to contact and systemic pesticides in arthropod pests.

Bioensaios de Resistência a Inseticidas Monitoramento

Pest resistance to pesticides is an increasing problem because pesticides are an integral part of high-yielding production agriculture. When few products ...

Biologia

Implementation of In Vitro Drug Resistance Assays: Maximizing the Potential for Uncovering Clinically Relevant Resistance Mechanisms

Although targeted therapies are initially effective, resistance inevitably emerges. Several methods, such as genetic analysis of resistant clinical specimens, have been applied to uncover these resistance mechanisms to facilitate follow-up care. Although these approaches have led to clinically relevant discoveries, difficulties in attaining the relevant patient material or in deconvoluting the genomic data collected from these specimens have severely hampered the path towards a cure. To this end, we here describe a tool for expeditious discovery that may guide improvement in first-line therapies and alternative clinical management strategies. By coupling preclinical in vitro or in vivo drug selection with next-generation sequencing, it is possible to identify genomic structural variations and/or gene expression alterations that may serve as functional drivers of resistance. This approach facilitates the spontaneous emergence of alterations, enhancing the probability that these mechanisms may be observed in the patients. In this protocol we provide guidelines to maximize the potential for uncovering single nucleotide variants that drive resistance using adherent lines.

Implementation of In Vitro Drug Resistance Assays: Maximizing the Potential for Uncovering Clinically Relevant Resistance Mechanisms

Drug resistance to targeted therapeutics is widespread and the need to identify mechanisms of resistance--prior to or following clinical onset--is critical for guiding alternative clinical management strategies. Here, we present a protocol to couple derivation of drug-resistant lines in vitro with sequencing to expedite discovery of these mechanisms.

Implementação de<em&gt; In Vitro</em&gt; Droga de Resistência Ensaios: maximizar o potencial para Descobrindo clinicamente relevantes mecanismos de resistência

Although targeted therapies are initially effective, resistance inevitably emerges. Several methods, such as genetic analysis of resistant clinical ...

Medicina

Characterizing Herbivore Resistance Mechanisms: Spittlebugs on Brachiaria spp. as an Example

Plants can resist herbivore damage through three broad mechanisms: antixenosis, antibiosis and tolerance1. Antixenosis is the degree to which the plant is avoided when the herbivore is able to select other plants2. Antibiosis is the degree to which the plant affects the fitness of the herbivore feeding on it1.Tolerance is the degree to which the plant can withstand or repair damage caused by the herbivore, without compromising the herbivore's growth and reproduction1. The durability of herbivore resistance in an agricultural setting depends to a great extent on the resistance mechanism favored during crop breeding efforts3.
We demonstrate a no-choice experiment designed to estimate the relative contributions of antibiosis and tolerance to spittlebug resistance in Brachiaria spp. Several species of African grasses of the genus Brachiaria are valuable forage and pasture plants in the Neotropics, but they can be severely challenged by several native species of spittlebugs (Hemiptera: Cercopidae)4.To assess their resistance to spittlebugs, plants are vegetatively-propagated by stem cuttings and allowed to grow for approximately one month, allowing the growth of superficial roots on which spittlebugs can feed. At that point, each test plant is individually challenged with six spittlebug eggs near hatching. Infestations are allowed to progress for one month before evaluating plant damage and insect survival. Scoring plant damage provides an estimate of tolerance while scoring insect survival provides an estimate of antibiosis. This protocol has facilitated our plant breeding objective to enhance spittlebug resistance in commercial brachiariagrases5.

Characterizing Herbivore Resistance Mechanisms: Spittlebugs on Brachiaria spp. as an Example

This video explains mechanisms of host plant resistance to herbivory and demonstrates a no-choice test that estimates the relative contributions of antibiosis and tolerance to spittlebug resistance in Brachiaria spp.

Mecanismos Herbívoro caracterizando Resistance: Spittlebugs em Brachiaria Spp. como Exemplo

Plants can resist herbivore damage through three broad mechanisms: antixenosis, antibiosis and tolerance1. Antixenosis is the degree to which the plant is ...

A PCR-based Genotyping Method to Distinguish Between Wild-type and Ornamental Varieties of Imperata cylindrica

Wild-type I. cylindrica (cogongrass) is one of the top ten worst invasive plants in the world, negatively impacting agricultural and natural resources in 73 different countries throughout Africa, Asia, Europe, New Zealand, Oceania and the Americas1-2. Cogongrass forms rapidly-spreading, monodominant stands that displace a large variety of native plant species and in turn threaten the native animals that depend on the displaced native plant species for forage and shelter. To add to the problem, an ornamental variety [I. cylindrica var. koenigii (Retzius)] is widely marketed under the names of Imperata cylindrica 'Rubra', Red Baron, and Japanese blood grass (JBG). This variety is putatively sterile and noninvasive and is considered a desirable ornamental for its red-colored leaves. However, under the correct conditions, JBG can produce viable seed (Carol Holko, 2009 personal communication) and can revert to a green invasive form that is often indistinguishable from cogongrass as it takes on the distinguishing characteristics of the wild-type invasive variety4 (Figure 1). This makes identification using morphology a difficult task even for well-trained plant taxonomists. Reversion of JBG to an aggressive green phenotype is also not a rare occurrence. Using sequence comparisons of coding and variable regions in both nuclear and chloroplast DNA, we have confirmed that JBG has reverted to the green invasive within the states of Maryland, South Carolina, and Missouri. JBG has been sold and planted in just about every state in the continental U.S. where there is not an active cogongrass infestation. The extent of the revert problem in not well understood because reverted plants are undocumented and often destroyed.
Application of this molecular protocol provides a method to identify JBG reverts and can help keep these varieties from co-occurring and possibly hybridizing. Cogongrass is an obligate outcrosser and, when crossed with a different genotype, can produce viable wind-dispersed seeds that spread cogongrass over wide distances5-7. JBG has a slightly different genotype than cogongrass and may be able to form viable hybrids with cogongrass. To add to the problem, JBG is more cold and shade tolerant than cogongrass8-10, and gene flow between these two varieties is likely to generate hybrids that are more aggressive, shade tolerant, and cold hardy than wild-type cogongrass. While wild-type cogongrass currently infests over 490 million hectares worldwide, in the Southeast U.S. it infests over 500,000 hectares and is capable of occupying most of the U.S. as it rapidly spreads northward due to its broad niche and geographic potential3,7,11. The potential of a genetic crossing is a serious concern for the USDA-APHIS Federal Noxious Week Program. Currently, the USDA-APHIS prohibits JBG in states where there are major cogongrass infestations (e.g., Florida, Alabama, Mississippi). However, preventing the two varieties from combining can prove more difficult as cogongrass and JBG expand their distributions. Furthermore, the distribution of the JBG revert is currently unknown and without the ability to identify these varieties through morphology, some cogongrass infestations may be the result of JBG reverts. Unfortunately, current molecular methods of identification typically rely on AFLP (Amplified Fragment Length Polymorphisms) and DNA sequencing, both of which are time consuming and costly. Here, we present the first cost-effective and reliable PCR-based molecular genotyping method to accurately distinguish between cogongrass and JBG revert.

A PCR-based Genotyping Method to Distinguish Between Wild-type and Ornamental Varieties of Imperata cylindrica

We provide a cost-effective and rapid molecular genotyping protocol that employs variety-specific PCR primers that target DNA sequence differences within the chloroplast trnL-F spacer region to differentiate between varieties of Imperata cylindrica (cogongrass) that cannot be distinguished by morphology alone. These varieties include the federally listed noxious weed, cogongrass and closely-related, wide-spread ornamental variety, I. cylindrica var. koenigii (Japanese blood grass).

Um método de genotipagem baseados em PCR para distinguir entre variedades do tipo selvagem e Ornamental de Imperata cylindrica</em

Wild-type I. cylindrica (cogongrass) is one of the top ten worst invasive plants in the world, negatively impacting agricultural and natural resources in ...

Repeatable Stair-step Assay to Access the Allelopathic Potential of Weedy Rice (Oryza sativa ssp.)

Weed competition contributes significantly to yield losses in cropping systems worldwide. The evolution of resistance in many weed species to continuously applied herbicides has presented the need for additional management methods. Allelopathy is a physiological process that some plant species possess that provide the plant with an advantage over its neighbors. Allelopathic crop varieties would be equipped with the ability to suppress the growth of surrounding competitors, thus reducing potential yield loss due to weed interference. This paper focuses on the construction and operation of a stair-step assay used for the screening of the allelopathic potential of a donor species (Oryza sativa) against a receiver weed species (Echinochloa crus-galli) in a greenhouse setting. The structure described in this paper serves as a stand for the plant samples and incorporates a timed watering system for the accumulation and distribution of allelochemicals. Allelochemicals produced by the plant roots are allowed to flow downward through a series of four pots separately into a collection tank and recycled back to the top plant through electric pumps. This method of screening provides an avenue for the allelochemicals from the donor plant to reach receiver plants without any resource competition, thus allowing quantitative measurement of the allelopathic potential of the selected donor plant. The allelopathic potential is measurable through the height reduction of the receiver plants. Preliminary screening data for the effectiveness of this method demonstrated height reduction in the receiver species, barnyardgrass (E. crus-galli), and thus the presence of allelopathic residues from the donor plant, weedy rice (Oryza sativa).

Repeatable Stair-step Assay to Access the Allelopathic Potential of Weedy Rice Oryza sativa ssp.

Allelopathy has shown promise as a useful supplemental weed control strategy in cropping systems. To determine the allelopathic potential of a desired plant specimen, a stair-step screening method is provided.

Ensaio repetível de escadaria para acessar o potencial allelopático de Arroz Weedy (Oryza sativa ssp.)

Weed competition contributes significantly to yield losses in cropping systems worldwide. The evolution of resistance in many weed species to continuously ...

Protocolos para Robust Teste de resistência a herbicidas em diferentes espécies de plantas daninhas

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