RESUMO -Este trabalho foi conduzido com o objetivo de caracterizar agronomicamente genótipos de cornichão (Lotus corniculatus L.), incluindo oito populações do cv. São Gabriel, um cultivar rizomatoso (cv. ARS-2620) e um cultivar sem rizomas (cv. Trueno). Plantas individuais foram cultivadas e submetidas a sete cortes em condições de campo, durante um ano, em Passo Fundo, Rio Grande do Sul, Brasil. Os genótipos apresentaram variabilidade quanto ao comprimento de entrenós, estatura, diâmetro, comprimento de legumes, produção de forragem e valor nutritivo. Na média geral, as populações e o cv. Trueno foram cerca de 50% mais produtivos em relação ao cv. ARS-2620. Os genótipos apresentaram entre 80 e 100% de sobrevivência. O conteúdo de proteína bruta reduziu de 21,8% (estádio vegetativo) para 11,2% (estádio de frutificação). A média geral de fibra detergente ácido foi de 24,2% e a de fibra detergente neutro variou entre 55,3 e 58,8%.Palavras-chave: forragem, rizomatoso, valor nutritivo Agronomic Characterization if Birdsfoot Trefoil Genotypes (Lotus corniculatus L.)ABSTRACT -This work was carried out to characterize agronomically birdsfoot trefoil (Lotus corniculatus L.) genotypes, including eight populations derived from the cultivar São Gabriel, one rhizomatous cultivar (ARS-260) and one cultivar without rhizomes (Trueno). Individual plants were submitted to seven cuts under field conditions during one year, at Passo Fundo, Rio Grande do Sul, Brazil. The genotypes showed variability relative to internode lenght, height, diameter, legume lenght, forage production and nutritive value. On the average, the populations and the cv. Trueno were about 50% more productive than the cv. ARS-260. The genotypes presented a survival range from 80% to 100%. The crude protein content decreased from 21.8 (vegetative stage) to 11.2% (fruiting stage). The overall mean for acid detergent fiber was 24.2% and the neutral detergent fiber ranged from 55.3% to 58.8%.
RESUMOPalavras-chave adicionais: Triticum aestivum, Gibberella zeae, Fusarium graminearum, fusariose, previsão da doença.O objetivo deste trabalho foi determinar as condições mínimas de duração do molhamento em função da temperatura requeridas para a infecção de giberela em trigo. O modelo climático desenvolvido por Zoldan (2008) foi testado em experimentos de campo com duas cultivares de trigo cultivadas em 2005 (cinco épocas de semeadura) e 2006 (seis épocas de semeadura) em parcelas de 10 m 2 com três repetições. A doença foi avaliada pela incidência em espigas (IE), incidência em espiguetas (Ie) e pela interação desses dois métodos e considerado como severidade. A partir do início da antese, a temperatura do ar e a duração do molhamento das espigas foram monitorados diariamente com uma estação meteorológica automática. Com a combinação desses dois fatores, foi Brustolin, R.; Zoldan, S. M.; Reis, E. M.; Zanatta, T.; Carmona, M. Requerimentos ambientais e previsão de chuva como indicador do momento para aplicação de fungicidas no controle da Giberela em trigo. Summa Phytopathologica, v.39, n.4, p.248-251, 2013. elaborada uma tabela de favorabilidade do ambiente para ocorrência da doença. A partir do dia do início da floração (1-5% anteras completamente expostas) a soma dos valores diários para favorabilidade para a infecção (SVDFI) foi calculada com um programa de computador, de acordo com a tabela de Zoldan (2008). Os sintomas iniciais da doença foram observados com uma incidência em espigas de 3,7% e correspondendo 2,6 de SVDFI. A infecção do trigo ocorre em função de chuvas que resultam no molhamento das espigas > 61.4 h de duração. A previsão da ocorrência de chuvas pode auxiliar na indicação do momento indicador da aplicação de fungicidas visando ao controle da giberela. Propõem-se o nome do sistema de aviso de UPF-scab-alert.The aim of this study was to determine the minimum conditions of wetness duration and mean temperature required for Fusarium head blight infection in wheat. The weather model developed by Zoldan (2008) was tested in field experiments for two wheat cultivars grown in 2005 (five sowing dates) and 2006 (six sowing dates) in 10 m 2 plots with three replicates. The disease was assessed according to head incidence (HI), spikelet incidence (SI), and the interaction between these two methods was called head blight severity (HBS). Starting at the beginning of anthesis, air temperature and head wetness duration were daily recorded with an automatic weather station. With Brustolin, R; Zoldan, S. M.; Reis, E. M.; Zanatta, T.; Carmona, M. Weather requirements and rain forecast to time fungicide application for Fusarium head blight control in wheat. Summa Phytopathologica, v.39, n.4, p.248-251, 2013. Additional keywords: Triticum aestivum, Gibberella zeae, Fusarium graminearum, scab, disease forecasting.ABSTRACT the combination of these two factors, a weather favorability table was built for the disease occurrence. Starting on the day of flowering beginning (1 -5% fully exserted anthers), the s...
A cultura do milho é uma das principais commodities da Argentina e do Brasil. Seu rendimento é reduzido por agentes nocivos, sendo um deles o fungo Exserohilum turcicum(Et)agente causal da helmintosporiose do milho.O presente trabalho teve como objetivo comparar as características morfológicas dos conídios e a patogenicidade de dez isolados de Etobtidos da Argentina e do Brasil. Cinco isolados monospóricos de cada país foram cultivados em meio lactose caseina hidrolizada ágar (LCHA) durante 15 dias a 25+2ºC e na ausência de luz. Prepararam-se lâminas microscópicas para a mensuração de 200 conidios de cada isolado. Na média os conídios mediram 10-25 x 30-135 μm, apresentando 2-8 septos. Detectaram-se diferenças estatísticas (p= 0,05) entre os dez isolados de Etpara todas as variáveis medidas (comprimento, largura e número de septos). Apesar da variação, as características mensuradas coincidiram com as registradas na literatura. Na comprovação da patogenicidade, plantas do híbrido de milho Pioneer P1630H, de conhecida suscetibilidade a Et, foram inoculadas com a deposição de 0,5 mL de uma suspensão de conídios de Etna concentração de 5x104 conídios/mL, no cartucho, quando atingiram a quarta folha expandida.Os dez isolados produziram, após os 15 dias da inoculação, uma média de 2,5 lesões/folha; de 39,7 x 3,4 mm de comprimento e largura respetivamente; e 4% de severidade estimada. Não se observou diferenças significativas na patogenicidade dos dez isolados estudados para nenhum dos critérios patométricos. Houve diferenças morfológicas entre os isolados da Argentina e do Brasil, porém não quanto à patogenicidade. Confirma-se que os isolados utilizados neste trabalho pertencem à espécie Et.
-The objective of this work was to evaluate the response of five birdsfoot trefoil populations (Lotus corniculatus L.), selected under severe and intense grazing (P38, P37, P9 and P3) or cutting (population Corte), one rhizomatous population from Morocco and two cultivars, São Gabriel (Brazil) and ARS 2620 (USA), to different cutting intervals (20 and 40 days). The trial was carried out in a greenhouse for 224 days. The plants were submitted to the treatments during four months, when it was made four and two cuttings for the 20 and 40 day intervals, respectively. In the following months, aerial part of the plants was totally removed and after 70 days of regrowth, evaluation of roots and aerial section were performed. Analysis of variance and multivariate analysis was performed, obtaining the Mahalanobis distance (Md), dendogram by UPGMA method and the relative contribution of the characters for genetic divergence. There was no genotype × cutting interval interaction and the genotypes presented a reduction on dry matter yield of roots, crown and aerial sections, number of stems and plant height when submitted to frequent cuttings. The most divergent genotypes were Marrocos and P9 (Md = 108.7) and the most similar ones were São Gabriel and P37 (Md = 7.8). The results suggest exclusion of the population P9 because of its weak performance and the utilization of the populations Corte and P37 as progenitors in the birdsfoot trefoil breeding program. Root dry matter accumulation and plant height were the characters that contributed most to genetic divergence and they can be used for selection works.
The longevity of Sclerotinia sclerotiorum sclerotia was quantified in an experiment carried out in the field. Sclerotia naturally formed in soybean plants in an infested commercial field were collected in a grain-cleaning machine and those present in the stem pith, with c.a. 8 mm in length and 1.9 mm in diameter were selected. Fifty sclerotia were kept inside a white nylon mesh (0.25mm) screen bag (25 x 25cm). Eighty bags were laid on the soil surface-simulating no till farming. At monthly intervals, four bags were taken and brought to the laboratory. Sclerotia were washed with tap water and surface desinfested with sodium hypochlorite and exposed to germinate on sterilized moist river sand in a growth chamber at 15oC and 12h photoperiod. After 12 months, sclerotia kept on the soil surface, lost their viability. It may be concluded that under no till, crop rotation with nonsusceptible crops, can reduce the sclerotia bank in the soil.
Northern corn leaf blight, caused by Exserohilum turcicum(Et), is one of the major corn diseases which can reduce grain yield and quality. The aim of this study was to determine the mycelial sensitivity of ten Etisolates, five from Argentina and five from Brazil, to six fungicides (carbendazim, captan, fludioxinil, metalaxyl, iprodione and thiram) used in seed treatment. The inhibitory concentration (IC50) was determined by using seven concentrations of the fungicides supplemented to the agar medium. The mycelial colony diameter was measured with a digital caliper. Experimental design was completely randomized with four replicates. Data on the percent mycelial growth inhibition were analyzed by logarithmic regression and the IC50 was calculated. The fungicide iprodione was the most potent, with IC50 < 0.01 mg/L, followed by fludioxonil, IC50 0.31 mg/L, and thiram, 1.37 mg/L. Carbendazim, metalaxyl and captan were classified as non-fungitoxic, showing IC50 > 50 mg/L for all isolates. Although iprodione is the most potent fungicide, it is not used for corn seed treatment. The IC50s obtained in this study can be used as baseline for future monitoring studies of Etsensitivity to fungicides.
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