Identificação e manejo da queima de folhas da cebola.

Neste comunicado, pretende-se fornecer informações para auxiliar na diagnose correta e no manejo da queima das folhas da cebola, visto que, nos últimos dois anos, epidemias severas de queima das folhas (B. squamosa) vêm ocorrendo em plantios conduzidos sob pivô central no Distrito Federal e em Goiás. A dificuldade de diagnosticar a doença e demora no seu controle têm levado a perda total de lavouras, acarretando grandes prejuízos aos produtores.

Irrigação na cultura do alho.

2014

Distribución de fertilizantes marcados con 15 N en la rotación ajo - moha

p.105-110

Evolução da qualidade de cebola armazenada, variedades "Pandero" e "Legend", em função da temperatura e aplicação de hidrazida maleica

A cebola representa no Ribatejo um dos produtos hortícolas de maior peso na economia agrícola regional. Os mercados dos produtos agrícolas são caracterizados por uma oferta contínua ao longo dos doze meses do ano. Actualmente é possível, garantir o fornecimento de cebola num apreciável período de tempo; no entanto, torna-se necessário proceder à sua conservação como forma de garantia de escoamento e regularização do abastecimento ao mercado. O material experimental constou de bolbos das variedades “Pandero” e “Legend” provenientes das plantações dos associados da Agromais e aplicação de um anti-abrolhante (hidrazida maleica), para que se tenha cebola não espigada com 6 meses de armazenamento, mantendo um equilíbrio no mercado durante o ano inteiro. As cebolas foram armazenadas em oito combinações; dois grupos da variedade “Pandero” um tratado outro não com HM, conservados a 4º C. Outros dois grupos da mesma variedade um tratado outro não com HM, conservados a 2,5ºC, repetindo a mesma forma na variedade “Legend”, com uma humidade relativa cerca de 75% (recomendada na conservação da cebola). Foram observadas as seguintes variáveis: podridão; espigamento; defeitos menores; defeitos maiores; defeitos totais e perda de peso. As observações foram realizadas em períodos de 15 em 15 dias, com os seguintes dias de conservação; 0; 16; 30; 46 e 59. O objectivo deste trabalho foi perceber os efeitos da hidrazida maleica e diferentes temperaturas (4 e 2,5ºC) sobre os parâmetros fisiológicos dos bolbos de cebola armazenados. Verificou-se uma menor podridão na temperatura a 2,5ºC, a HM reduziu o espigamento na variedade “Pandero” à temperatura de 4ºC, já sem HM o espigamento foi maior na “Pandero” à temperatura de 4ºC; com o abaixamento da temperatura de 4 para 2,5ºC houve uma redução de 5% no espigamento; os defeitos totais não foram afectados pela temperatura,

Estratégias de controlo da poluição das águas subterrâneas pelos nitratos de origem agrícola

Tese de dout., Ciências Agrárias, Faculdade de Engenharia de Recursos Naturais, Univ. do Algarve, 2003

Cebola: escolha adequada.

Com o objetivo de identificar genótipos de cebola mais adaptados e produtivos, e que atendam ao mercado consumidor nacional nas condições do Submédio do Vale do São Francisco.

Improving cropping systems of semi-arid south-western Madagascar under multiple ecological and socio-economic constraints

Das Mahafaly Plateau im südwestlichen Madagaskar ist gekennzeichnet durch raue klimatische Bedingungen, vor allem regelmäßige Dürren und Trockenperioden, geringe Infrastruktur, steigende Unsicherheit, hohe Analphabetenrate und regelmäßige Zerstörung der Ernte durch Heuschreckenplagen. Da 97% der Bevölkerung von der Landwirtschaft abhängen, ist eine Steigerung der Produktivität von Anbausystemen die Grundlage für eine Verbesserung der Lebensbedingungen und Ernährungssicherheit in der Mahafaly Region. Da wenig über die Produktivität von traditionellen extensiven und neu eingeführten Anbaumethoden in diesem Gebiet bekannt ist, waren die Zielsetzungen der vorliegenden Arbeit, die limitierenden Faktoren und vielversprechende alternative Anbaumethoden zu identifizieren und diese unter Feldbedingungen zu testen. Wir untersuchten die Auswirkungen von lokalem Viehmist und Holzkohle auf die Erträge von Maniok, der Hauptanbaufrucht der Region, sowie die Beiträge von weiteren Faktoren, die im Untersuchungsgebiet ertragslimitierend sind. Darüber hinaus wurde in der Küstenregion das Potenzial für bewässerten Gemüseanbau mit Mist und Holzkohle untersucht, um zu einer Diversifizierung von Einkommen und Ernährung beizutragen. Ein weiterer Schwerpunkt dieser Arbeit war die Schätzung von Taubildung und deren Beitrag in der Jahreswasserbilanz durch Testen eines neu entworfenen Taumessgerätes. Maniok wurde über drei Jahre und in drei Versuchsfeldern in zwei Dörfern auf dem Plateau angebaut, mit applizierten Zeburindermistraten von 5 und 10 t ha-1, Holzkohleraten von 0,5 und 2 t ha-1 und Maniokpflanzdichten von 4500 Pflanzen ha-1. Maniokknollenerträge auf Kontrollflächen erreichten 1 bis 1,8 t Trockenmasse (TM) ha-1. Mist führte zu einer Knollenertragssteigerung um 30 - 40% nach drei Jahren in einem kontinuierlich bewirtschafteten Feld mit geringer Bodenfruchtbarkeit, hatte aber keinen Effekt auf den anderen Versuchsfeldern. Holzkohle hatte keinen Einfluss auf Erträge über den gesamten Testzeitraum, während die Infektion mit Cassava-Mosaikvirus zu Ertragseinbußen um bis zu 30% führte. Pflanzenbestände wurden felder-und jahresübergreifend um 4-54% des vollen Bestandes reduziert, was vermutlich auf das Auftreten von Trockenperioden und geringe Vitalität von Pflanzmaterial zurückzuführen ist. Karotten (Daucus carota L. var. Nantaise) und Zwiebeln (Allium cepa L. var. Red Créole) wurden über zwei Trockenzeiten mit lokal erhältlichem Saatgut angebaut. Wir testeten die Auswirkungen von lokalem Rindermist mit einer Rate von 40 t ha-1, Holzkohle mit einer Rate von 10 t ha-1, sowie Beschattung auf die Gemüseernteerträge. Lokale Bewässerungswasser hatte einen Salzgehalt von 7,65 mS cm-1. Karotten- und Zwiebelerträge über Behandlungen und Jahre erreichten 0,24 bis 2,56 t TM ha-1 beziehungsweise 0,30 bis 4,07 DM t ha-1. Mist und Holzkohle hatten keinen Einfluss auf die Erträge beider Kulturen. Beschattung verringerte Karottenerträge um 33% im ersten Jahr, während sich die Erträge im zweiten Jahr um 65% erhöhten. Zwiebelerträge wurden unter Beschattung um 148% und 208% im ersten und zweiten Jahr erhöht. Salines Bewässerungswasser sowie Qualität des lokal verfügbaren Saatgutes reduzierten die Keimungsraten deutlich. Taubildung im Küstendorf Efoetsy betrug 58,4 mm und repräsentierte damit 19% der Niederschlagsmenge innerhalb des gesamten Beobachtungszeitraum von 18 Monaten. Dies weist darauf hin, dass Tau in der Tat einen wichtigen Beitrag zur jährlichen Wasserbilanz darstellt. Tageshöchstwerte erreichten 0,48 mm. Die getestete Tauwaage-Vorrichtung war in der Lage, die nächtliche Taubildung auf der metallischen Kondensationsplatte zuverlässig zu bestimmen. Im abschließenden Kapitel werden die limitierenden Faktoren für eine nachhaltige Intensivierung der Landwirtschaft in der Untersuchungsregion diskutiert.

Proyecto de investigación escolar : la genotoxicidad en los currículos del ciclo de enseñanza media y superior.

Se describe un proyecto de investigación escolar cuyo objetivo es acercar al alumnado del nivel medio educativo el concepto de biomonitoreo ambiental estudiando la genotoxicidad de las aguas superficiales próximas a su ambiente escolar. Se propone una actividad integradora de contenidos curriculares tradicionales y novedosos que se han incorporado con la reforma educativa argentina presentándose un tratamiento independiente de estos temas en el currículo de las ciencias naturales. La propuesta facilita el aprendizaje de conceptos de genética y contaminación ambiental desde un proceso participativo que asegura la adquisición de nuevos conocimientos, herramientas y habilidades. Se emplea el modelo experimental 'Allium Cepa' como bioindicador para evaluar el daño genético .

Two-photon excitation with pico-second fluorescence lifetime imaging to detect nuclear association of flavanols

Two-photon excitation enabled for the first time the observation and measurement of excited state fluorescence lifetimes from three flavanols in solution, which were ∼1.0 ns for catechin and epicatechin, but <45 ps for epigallocatechin gallate (EGCG). The shorter lifetime for EGCG is in line with a lower fluorescence quantum yield of 0.003 compared to catechin (0.015) and epicatechin (0.018). In vivo experiments with onion cells demonstrated that tryptophan and quercetin, which tend to be major contributors of background fluorescence in plant cells, have sufficiently low cross sections for two-photon excitation at 630 nm and therefore do not interfere with detection of externally added or endogenous flavanols in Allium cepa or Taxus baccata cells. Applying two-photon excitation to flavanols enabled 3-D fluorescence lifetime imaging microscopy and showed that added EGCG penetrated the whole nucleus of onion cells. Interestingly, EGCG and catechin showed different lifetime behaviour when bound to the nucleus: EGCG lifetime increased from <45 to 200 ps, whilst catechin lifetime decreased from 1.0 ns to 500 ps. Semi-quantitative measurements revealed that the relative ratios of EGCG concentrations in nucleoli associated vesicles: nucleus: cytoplasm were ca. 100:10:1. Solution experiments with catechin, epicatechin and histone proteins provided preliminary evidence, via the appearance of a second lifetime (τ2 = 1.9–3.1 ns), that both flavanols may be interacting with histone proteins. We conclude that there is significant nuclear absorption of flavanols. This advanced imaging using two-photon excitation and biophysical techniques described here will prove valuable for probing the intracellular trafficking and functions of flavanols, such as EGCG, which is the major flavanol of green tea.

Ethylene and 1-methylcyclopropene differentially regulate gene expression during onion sprout suppression

Onion (Allium cepa) is regarded as a nonclimacteric vegetable. In onions, however, ethylene can suppress sprouting while the ethylene-binding inhibitor 1-methylcyclopropene (1-MCP) can also suppress sprout growth; yet, it is unknown how ethylene and 1-MCP elicit the same response. In this study, onions were treated with 10 mu L L(-1) ethylene or 1 mu L L(-1) 1-MCP individually or in combination for 24 h at 20 degrees C before or after curing (6 weeks) at 20 degrees C or 28 degrees C and then stored at 1 degrees C. Following curing, a subset of these same onions was stored separately under continuous air or ethylene (10 mu L L(-1)) at 1 degrees C. Onions treated with ethylene and 1-MCP in combination after curing for 24 h had reduced sprout growth as compared with the control 25 weeks after harvest. Sprout growth following storage beyond 25 weeks was only reduced through continuous ethylene treatment. This observation was supported by a higher proportion of down-regulated genes characterized as being involved in photosynthesis, measured using a newly developed onion microarray. Physiological and biochemical data suggested that ethylene was being perceived in the presence of 1-MCP, since sprout growth was reduced in onions treated with 1-MCP and ethylene applied in combination but not when applied individually. A cluster of probes representing transcripts up-regulated by 1-MCP alone but down-regulated by ethylene alone or in the presence of 1-MCP support this suggestion. Ethylene and 1-MCP both down-regulated a probe tentatively annotated as an ethylene receptor as well as ethylene-insensitive 3, suggesting that both treatments down-regulate the perception and signaling events of ethylene.

Evaluation of the Genotoxicity of Chitosan Nanoparticles for Use in Food Packaging Films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of the genotoxicity of cellulose nanofibers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise da presença de agentes mutagênicos nas águas do Rio Pitimbú/RN

The Pitimbu River is located at the oriental portion of the State of Rio Grande do Norte, including three importants cities named Macaíba, Parnamirim e Natal. Although its high importance as a water source, which supplys great part of the South Zone of the Natal city, this river receives a large quantity of domestic and industrial waste water without treatment. The Pitimbu River headhas its river-head located in the city of Macaiba, goes through Parnamirim, then it flowing into at the Jiqui Lake in Natal. The aim of this study was to evaluate, qualitatively and quantitatively, the environmental quality of the Pitimbu River by genotoxicity bio-assays, which are important tools for genetics toxicological evaluation. In this work, five samples sites, distributed along the river, were used to collect water samples. Another point site, located near Jiqui lake, was used to collect drinkable water, which was treated by CAERN, the water treatment entreprise of Rio Grande do Norte. The following assays where used to evaluate the quality of these samples: Allium cepa assay; Comet assay; Micronuclei (MN) assay; and Ames test. For the Allium cepa assay, sixteen specimes where used for each water sample from the sample sites. In this assay both microscopic, like cytogenetic damage, and macroscopic aspects, as morphological variation were evaluated. Red blood cells from periferical blood of the Crenicichla menezesi native specie were used not only for the MN assay, but also for the Comet assay. These fishes were collected at different points on the Pitimbu River and the negative control was developed using fishes of the same species that were bring to the laboratory and maintained for 100 days in the optimal experimental conditions. For the Ames test, TA100, YG1042, TA98 and YG1041 strains were used in the directed method without metabolic activation. The results found by the Allium cepa assay showed that two water sample sites induced increase of mitotic index (IM). Additionally, compared to the control, all the water samples increased the chromossomal aberrations frequency and/or micronucleus. Among the sample sites, two also showed an abnormal growth rate in its root and two samples induced morphological alteration. With the MN test in red blood cells, a high frequence of MN was observed in tree sample. By comparing all the results obtained on the water sample points and with the negative control, a significant variation on the MN frequency was observed. Positive results were also observed for the same sample to water test by the Comet assay. These results allow concluding that the proposed specie Crenicichla menezesi has a good profile as a bio-indicator for the evaluation of environmental water quality and the MN and comet test can be usuful for in situ evaluation. By the Ames test, it was possible to detect the mutagenic activity on the waters from the Pitimbu River in different levels of mutagenicity. This result suggests that this river has several substances that induced changes directly to the DNA. The mechanisms involved to this phenomenon could be by both processes, by changing of the reading frame and by nucleotide substitution. These data set indicate the presence of mutagenic agents, which can represent in risk to biot and human beens

Sesquiterpene lactones as allelochemicals

Six new sesquiterpene lactones, annuolide H ( 3), helivypolides F, H-J ( 4, 11-13), and helieudesmanolide A ( 6), together with known compounds, were isolated from polar bioactive fractions of Helianthus annuus cv. SH-222 and Stella fresh leaf water extracts. Spectroscopic analysis of the new data for 1,2-anhydroniveusin A and 1-methoxy-4,5-dihydroniveusin A corrects some previous assignments. The compounds were tested using the etiolated wheat coleoptile bioassay, and the most active compounds were assayed in standard target species ( STS) ( Lepidium sativum, Allium cepa, Lactuca sativa, Lycopersicon esculentum, and Triticum aestivum) from 5 x 10(-4) to 10(-5) M. The most phytotoxic compounds were helivypolide F and 15-hydroxy-3-dehydrodeoxyfruticin, both of which have a carbonyl group at C-3 conjugated with two double bonds.

Efeito de diferentes períodos de controle das plantas daninhas na produtividade da cultura da cebola

Foi realizado um experimento em Monte Alto-SP, visando estudar os efeitos de diferentes períodos de controle das plantas daninhas sobre a produção de bulbos da cultura da cebola (Allium cepa), cultivar 'Mercedes', no sistema de transplantio. O delineamento experimental utilizado foi o de blocos ao acaso, com quatro repetições. Parte dos tratamentos experimentais foi disposta num esquema fatorial 4 x 6, em que constituíram variáveis quatro períodos em que se fez o controle (0-0, 0-7, 0-14 e 0-21 DAT) e seis períodos em que se reiniciou o controle das plantas daninhas prolongando até a colheita: 28, 42, 56, 70, 84 e 98 DAT). Duas testemunhas foram adotadas: uma com controle e outra sem controle das plantas daninhas durante todo o ciclo da cultura. Lycopersicon esculentum, Portulaca oleracea, Eragrostis pilosa e Galinsoga parviflora foram as plantas daninhas mais importantes na área. Não houve interação entre os diferentes períodos de controle das plantas daninhas. O controle inicial destas plantas deve se prolongar até 14 DAT e ser reiniciado aos 28 DAT, a fim de prevenir reduções significativas na produtividade em relação à testemunha no limpo A convivência com as plantas daninhas durante todo o ciclo da cebola reduziu a produtividade em 94,5%.