Flávia Rodrigues Alves Patrício

Efeito da solarização sobre propriedades físicas, químicas e biológicas de solos

Solarization is a method for soil disinfestation, taking effect by increased soil temperatures under soil covers of transparent polyethylene sheets during the period of intense solar irradiation. Four field experiments were set up in the state of Sao Paulo, Brazil (districts of Mogi das Cruzes, Jarinu, Piracicaba and Itatiba), in the years 2000 and 2001, to evaluate the effects of soil solarization on physical, chemical and biological soil properties. Solarization caused a significant reduction in penetration resistance of the evaluated soils in Jarinu, Piracicaba, and Itatiba. In Jarinu, measurements carried out eight months after the removal of the plastic sheet showed that the effect of solarization on penetration resistance was still similar to that observed in the first evaluation. However, in Mogi das Cruzes, in an organic soil, solarization increased the soils penetration resistance in the 2.5-5.0 cm layer. Solarization did not affect the macro-, micro- and total porosity of soils in Piracicaba and Jarinu, where these properties were measured, however it did reduce the apparent density. In an evaluation by fluorescein diacetate hydrolysis, the microbial activity in the soil proved to decrease by solarization. In Mogi das Cruzes, the suppressiveness to Fusarium oxysporum f. sp. phaseoli was evaluated in vitro by colonizing soil samples with an isolate marked with benomyl resistance. Solarization reduced the recovery of the pathogen, indicating an increase in suppressiveness. In solarized plots, there was a significant increase in the concentration of NH4+-N in all experiments, of Mn in three, of NO3--N, Mg2+, and base saturation in two, and K+ in one experiment. On the other hand, the concentration of Cu, Fe, and H + Al decreased in two places, and Zn in one. Results showed that solarization caused changes in physical, chemical and biological soil properties, improving the soil structure, releasing nutrients, and increasing disease suppressiveness.

Resposta de cultivares de trigo (Triticum aestivum L.) ao controle químico das principais doenças fúngicas da cultura

Leaf rust, leaf spot or brown spot and powdery mildew, caused by Puccinia recondita tritici, Bipolaris sorokiniana and Blumeria graminis tritici, respectively, are wheat diseases that may severely decrease crop yield. Several practices are recommended for the control of these diseases such as cultivar resistance, planting at a suitable time, and chemical control, without which the crop frequently becomes uneconomical. The objective of the present work was to evaluate, under field conditions, the response of six wheat cultivars, IAC 24, IAC 289, IAC 350, IAC 362, IAC 364 and IAC 370, in four experiments, carried out from 2000 to 2003 at Capao Bonito, State of Sao Paulo, Brazil. The experiments were set out in a randomized block design with four replications, and analyzed as a 2 x 6 factorial, being fungicide treatment (with and without) the factor 1 and cultivar the factor 2. Severity of the diseases was graded in a scale that ranged from 0 to 9, (0 = without symptoms and 9 > 60% of the foliar area affected by disease). Grain yield and the thousand kernel weight (TKW) were also assessed in each experiment. Powdery mildew was only observed in 2000, but leaf rust was detected in all years in high severity indexes (30 to 60% of leaf area affected by the disease). Leaf spot, detected in the last three years, from 2001 to 2003, showed the highest severity indexes in the rainiest year, 2001 (up to 60 % of the leaf affected by the disease). In all years the fungicides were efficient to control the diseases in all experiments and resulted in higher TKW and in grain yield increases. The cultivars with the longest crop cycles, IAC 370, IAC 289 and IAC 350, had the highest responses in yield to the chemical control, despite the fact that the last two cultivars were less affected by the diseases in the control plots, showing that not only cultivar resistance, but the crop cycle and the yield potential, characteristic of each cultivar, were important in the response to the chemical control.

Resistência de plantas de coffea arabica, coffea canephora e híbridos interespecíficos à cercosporiose

In the present study plants of Coffea arabica, C. canephora, and interespecific hybrids were evaluated on their response to brown eye spot (Cercospora coffeicola), an important disease of the coffee crop. Two experiments were carried out in 2003 in Campinas, SP, with seedlings of C. arabica cultivars Mundo Novo IAC 388-17-1, Mundo Novo IAC 376-4, Bourbon Amarelo, Bourbon Vermelho, Obata IAC 1669-20, Catuai Vermelho IAC 144, Catuai Amarelo IAC 62, Icatu Precoce IAC 3282, Icatu Vermelho IAC 4045, Ouro Verde IAC H5010-5, Tupi IAC 1669-33, of C. canephora, Robusta IAC 1653-7 and Apoata IAC 2258, as well as two interspecific hybrids Piata IAC 387 and Hibrido de Timor IAC 1559-13. The seedlings were inoculated with a conidial suspension containing a mixture of five isolates of C. coffeicola collected in different regions of Sao Paulo State. The most susceptible materials were Robusta IAC 1653-7, Apoata IAC 2258, Hibrido de Timor IAC 1559-13, Bourbon Vermelho, and Bourbon Amarelo, with levels of incidence that varied from 81.6 to 63.1% in the first experiment, and from 70 to 93.3% in the second, and severity (graded scale 1-6) from 2.92 and 3.42 in the first experiment to 2.79 and 3.64 in the second. The most resistant materials were Piata IAC 387, Ouro Verde IAC H5010-5 and Tupi IAC 1669-33, with incidence between 28.4 and 35.5 % in the first experiment and between 21.1 and 55.6%, in the second, and severity that varied from 1.44 to 1.73 in the first experiment to 1.28 to 1.88 in the second.

Induction of systemic resistance by rhizobacteria in hydroponic system

Rhizobacteria of the fluorescent group of Pseudomonas spp. were selected for both their capacity in the growth promotion of lettuce seedlings (Lactuca sativa L.) and antagonistic activity against Pythium aphanidermatum from test in vitro. Then, in hydroponic system was assayed the previous application of the Pseudomonas strains in order to reduce damages caused by P. aphanidermatum in cucumber (Cucumis sativus) for induced systemic resistance (ISR), using a technical split-root. The variables shoots and roots dry weight and root length were used in evaluation. The production of antagonistic and/or growth promoters compounds by rhizobacteria strains was observed to associate its activity with the results obtained in the tests under hydroponic system and in vitro conditions. In the in vitro experiment, strains Ps 140B and Ps 140C provided the largest development of plants (root and hypocotyls) in the treatments with and without pathogen. Some strains tested indicating a possible expression of ISR in in vivo experiments. No correspondence among the compounds produced by rhizobacteria, plant growth promotion and bioprotection was detected.

Método do rolo de papel toalha modificado para a detecção de Sclerotinia sclerotiorum em sementes de feijão

White mold, caused by the fungus Sclerotinia sclerotiorum (Lib.) is one of the most damaging diseases of beans. Dissemination of the pathogen by infected seeds is important because it can infest new planting areas and the disease may establish in the beginning of the crop cycle. The present work describes an adaptation of the seed health test using the germination paper towel method, originally developed for the detection of Colletotrichum lindemuthianum, for assessing the presence of S. sclerotiorum in bean seeds. The test consisted of placing bean seeds in germination paper towels, which were rolled and placed in a germination chamber and kept at 100% relative humidity and 20 oC for seven days. After this period, the infected seedlings and the dead seeds surrounded by a white cottony growth were collected and placed in a gerbox over two wet filter papers. The sclerotia characteristic of the pathogen appeared around the seeds after tree to four days of incubation. This method is relatively rapid, inexpensive, and has the additional advantage of detecting simultaneously other important plant pathogens in bean seeds, such as Colletotrichum lindemuthianum, Macrophomina phaseolina and Rhizoctonia solani.

Proteção do cafeeiro contra cercosporiose por acibenzolar-S-metil e proteína harpina

The objective of this work was to evaluate the protective effect of harpin protein and acibenzolar-S-methyl (ASM) against brown eye spot, in coffee plants, and its effect on in vitro conidial germination and mycelial growth of Cercospora coffeicola. In the first assay, plants treated with ASM (25, 50, 100, 200 µg mL -1 ) received the inoculum of a C. coffeicola conidial suspension, and the disease severity was evaluated 30 and 60 days after inoculation. In the second assay, plants were sprayed with harpin (7.5, 15, 30, 60, 120 µg mL -1 ) following the same procedure. In a third trial, plants previously sprayed with ASM (200 µg mL -1 ) or harpin (15 µg mL -1 ) were treated again with these products 30 days after pathogen inoculation. ASM and harpin protected the coffe plants against brown eye spot 30 days after inoculation with C. coffeicola. However, 60 days after inoculation, only ASM (200 µg mL -1 ), with one or two applications, conferred protection to plants against C. coffeicola. Coffee plants were protected against cercosporiosis, when harpin was reapplied on plants 30 days after a previous treatment with this protein. Harpin and acibenzolar-S-methyl did not inhibit the in vitro conidial germination and the mycelial growth of the pathogen.

Solarização do solo com filmes plásticos com e sem aditivo estabilizador de luz ultravioleta

Visando auxiliar na escolha de filmes plasticos adequados para a solarizacao, dois experimentos foram instalados em Mogi das Cruzes e Piracicaba (SP), em janeiro e fevereiro de 2000. Tres tipos de filmes plasticos transparentes de polietileno de baixa densidade (PEBD), com 100 mm de espessura, produzidos pela empresa Nortene Plasticos Ltda., foram testados: a) FES, filme estufa super tricarpa super aditivado, com aditivo estabilizador de luz ultravioleta (baseado em aminas estericamente impedidas); b) FSOL, filme para solarizacao produzido com metade da quantidade do mesmo aditivo e c) LT, lona plastica transparente, sem aditivo, alem de uma testemunha sem cobertura plastica, em delineamento de blocos casualizados, com quatro repeticoes. Apos a retirada dos plasticos foi conduzida uma safra de alface em ambos os locais. Foi realizada analise quimica dos solos e das plantas colhidas, alem de avaliada a infestacao por plantas daninhas e a massa fresca das plantas colhidas. Em Piracicaba tambem foram realizadas analises microbiologicas dos solos e determinada a viabilidade de Pythium aphanidermattum. Em Mogi das Cruzes foi avaliada a incidencia de podridao de esclerotinia, causada por Sclerotinia minor. As temperaturas medias registradas, a 10 cm de profundidade, nos solos sob os diferentes filmes plasticos foram semelhantes, de 44-41oC nos solos solarizados e de 33,9-30,2oC nos solos nao solarizados de Piracicaba e Mogi das Cruzes, respectivamente. Detectou-se aumento na massa fresca das plantas colhidas nas parcelas solarizadas, de 49% em Piracicaba e 24% em Mogi das Cruzes, independente do plastico testado. Nos dois locais tambem houve drastica reducao na infestacao por plantas daninhas nas areas solarizadas. Nas analises microbianas nao foram verificadas alteracoes na liberacao de CO2, no carbono da biomassa microbiana, no quociente metabolico e no numero total de bacterias. O numero de fungos foi menor nos tratamentos com plastico contendo aditivo. A viabilidade de P. aphanidermatum foi reduzida em todos os tratamentos solarizados, independente do plastico utilizado. Houve aumento no pH, na saturacao por bases (V%) e nos teores de NH4+ (190%), Mn (94,6%) e Mg2+ (18%), dos solos solarizados. Tambem as plantas de alface colhidas nessas parcelas apresentaram maiores teores de Zn (43%), Mg2+ (12%) e K+ (4%). Em Mogi das Cruzes foram observados aumentos nos teores de Mn (236%) e Cu (18%) nos solos solarizados e nas plantas colhidas nesses tratamentos (aumento de 99% para Mn e de 27% para Cu). A incidencia da podridao de esclerotinia foi reduzida de 27,7% na testemunha para indices inferiores a 1% nas parcelas solarizadas com os diferentes filmes plasticos. O plastico sem aditivo estabilizador de luz ultravioleta partiu-se durante ambos os experimentos, apos 60 e 90 dias de exposicao ao ambiente, sendo considerado inadequado para a solarizacao, mas nao houve diferenca entre os plasticos para nenhum atributo avaliado.

Effect of temperature on mycelial growth of Trichoderma, Sclerotinia minor and S. sclerotiorum, as well as on mycoparasitism

As condicoes ambientais sao muito importantes para o controle biologico de doencas de plantas. Em um estudo previo, isolados de Trichoderma asperellum (IBLF 897, IBLF 904 e IBLF 914) e T. asperelloides (IBLF 908) foram selecionados como antagonistas a Sclerotinia minor e S. sclerotiorum, agentes causais da murcha de esclerotinia, uma das mais importantes doencas da cultura da alface. Neste estudo subsequente o crescimento micelial destes isolados e dos patogenos foi avaliado em diferentes temperaturas, assim como o micoparasitismo do isolado IBLF 914. O crescimento micelial dos isolados de T. asperellum e T. asperelloides, bem como de S. minor e S. sclerotiorum, foi avaliado em temperaturas variando de 7 a 42 oC. O parasitismo de propagulos de S. minor e S. sclerotiorum pelo isolado IBLF 914, assim como o numero de plântulas de alface sobreviventes ao tombamento, foram avaliados aos 12, 17, 22, 27 e 32 oC em caixas gerbox contendo substrato. S. minor e S. sclerotiorum apresentaram crescimento micelial nas temperaturas de 7 a 27 °C, mas nao cresceram a 32 °C e ambos os patogenos apresentaram maior crescimento micelial a 22 °C. Os isolados de Trichoderma cresceram em temperaturas entre 12 e 37°C, com um maximo a 27 oC. O isolado IBLF 914 exibiu micoparasitismo e reduziu a doenca nas plântulas de alface em temperaturas entre 22 e 32°C. Como a murcha de esclerotinia ocorre quando predominam temperaturas amenas e elevada umidade e o antagonista foi mais efetivo em temperaturas medias a elevadas, sugere-se que Trichoderma seja aplicado em lavouras de alface no Brasil tambem nos meses mais quentes do ano visando a reduzir o inoculo presente no solo antes da instalacao da cultura de inverno, mais afetada pela doenca.

Control of lettuce bottom rot by isolates of Trichoderma spp.

A queima da saia, causada por Rhizoctonia solani AG 1-IB, e uma importante doenca da cultura da alface no Brasil, para a qual o controle biologico com Trichoderma nao foi desenvolvido ate o momento no pais. O presente estudo foi realizado com o objetivo de selecionar isolados de Trichoderma para serem usados para o controle da queima da saia em alface. Quarenta e seis isolados de Trichoderma obtidos com iscas contendo micelio do patogeno foram avaliados em experimentos conduzidos in vitro e in vivo, os quais foram realizados em casa de vegetacao, em duas fases.Em laboratorio os isolados foram avaliados com relacao as capacidades de parasitismo e de producao de substâncias metabolicas toxicas, com capacidade de inibir o crescimento micelial do patogeno. Na primeira fase dos experimentos in vivo, foram avaliados o numero e a massa seca de plântulas de alface da cultivar White Boston. Na segunda fase, 12 isolados eficientes na primeira fase e que tambem apresentaram rapido crescimento e esporulacao abundante em laboratorio, foram avaliados com relacao a sua capacidade de controlar a queima da saia em dois experimentos repetidos, e tambem tiveram suas especies identificadas. A maioria dos isolados de Trichoderma spp. (76%) apresentou elevada capacidade de parasitismo e 50% dos isolados produzim metabolitos toxicos capazes de inibir 60-100% do crescimento micelial de R. solani AG1-1-B. Vinte e quatro isolados promoveram aumento do numero e 23 na massa seca de plântulas de alface inoculadas com o patogeno na primeira fase dos experimentos in vivo. Nos dois experimentos da segunda fase dois isolados de T. virens, IBLF 04 e IBLF 50, reduziram a severidade da queima da saia e promoveram o aumento do numero e da massa seca das plântulas de alface inoculadas com R. solani AG 1-IB. Esses isolados haviam apresentado elevada capacidade de parasitismo e de producao de substâncias metabolicas toxicas, indicando que as fases in vitro e in vivo empregadas no presente estudo foram eficientes para a selecao dos antagonistas a serem utilizados para o controle da queima da saia em alface.

Variabilidade in vitro, in vivo e molecular de isolados de Cercospora coffeicola

Neste estudo, sete isolados de Cercospora coffeicola, agente causal da cercosporiose em cafeeiros, foram estudados com relacao ao crescimento micelial em diferentes temperaturas, comparacao das sequencias das regioes ITS1 e ITS2 do DNA ribossomico e de parte do gene da calmodulina, e com relacao a patogenicidade a oito cultivares de cafeeiro (Catuai Vermelho IAC 81, Catuai SH3, Tupi IAC 1669 - 33, Tupi RN IAC 1669 - 13, Icatu Vermelho IAC 4045, Ouro Verde IAC H 5010-5, Geisha IAC 1137 e Mundo Novo IAC 376-4). As temperaturas de maior crescimento micelial foram de 23,8, 23,7 e 23,9oC para os isolados IBLF277 (Franca, SP), IBLF280 (Sao Sebastiao do Paraiso, MG) e IBLF379 (Sao Joao do Manhuacu, MG), respectivamente; de 24,6oC e de 25,1oC para os isolados IBL199 (Patos de Minas, MG) e IBLF270 (Boa Esperanca, MG); e de 27,6 e 27,8oC, para os isolados IBLF004 (Campinas, SP) e IBLF206 (Patrocinio, MG). Na analise filogenetica os isolados IBLF270 e IBLF379 formaram um subgrupo unico, mas as sequencias do gene da calmodulina de todos os isolados apresentaram 100% de identidade. Os isolados IBLF277, IBLF270, IBLF379 e IBLF199 foram os mais patogenicos as mudas de cafeeiro das diferentes cultivares. A cultivar Ouro Verde IAC H 5010-5 foi a mais resistente a cercosporiose e as cultivares Geisha IAC 1137, Mundo Novo IAC 376-4 e Tupi IAC 1669-33 as mais suscetiveis, entretanto, no segundo experimento, houve interacao entre cultivares e isolados.