José Otávio Machado Menten

Diversidade e potencial biotecnológico da comunidade bacteriana endofítica de sementes de soja

Abstract – The objectives of this work were to isolate, characterize and identify the endophytic bacterial community of soybean seeds, and to test the biotechnological potential of this community. Seeds from 12 soybean cultivars were used. The endophytic bacterial isolates were evaluated for in vitro antagonism against phytopathogenic fungi, synthesis of indoleacetic acid (IAA), and capacity to solubilize phosphate. Isolation techniques, amplifi ed ribosomal DNA restriction analysis (ARDRA) grouping, and identifi cation by means of partially sequencing the 16S rDNA were used in community characterization. The isolates with best biotechnological potential were inoculated in seeds to evaluate their ability to promote plant growth. Twelve ribotypes were identify by means of ARDRA and classifi ed as: Acinetobacter , Bacillus , Brevibacterium , Chryseobacterium , Citrobacter , Curtobacterium , Enterobacter , Methylobacterium , Microbacterium , Micromonospora , Pantoea , Paenibacillus , Pseudomonas

Eficiência do fungicida carboxin + thiram no tratamento de sementes de amendoim

Fungicide seed treatment is a cheap insurance for peanut seed producers and growers. Correct fungicide use can contribute to better performance of the propagation material, increasing the yield. The objective of this research was to evaluate the efficiency of carboxin + thiram and the viability of the use of vegetable oil and an organo-sillicone based surphactant as fungicide vehicle for seed-borne fungi control. Two doses of carboxin + thiram (50 + 50 and 70 +70 g a.i./100 kg seeds) prepared in water, plus one dose ( 50 + 50 g a.i./100 kg ) mixed with the vegetable oil and the surphactant were tested. The evaluation was based on seed germination and vigour and further field establishment of the crop. It was verified that the most important benefits of seed treatment were the significative reduction of dead seeds and the pre-emergence damping-off. Both doses of fungicide prepared in water were efficient for the control of seed-born pathogens, except for Rhizopus sp. The vegetable oil and the surphactant provided better covering and adherence of the fungicide to seeds, increasing the efficiency for the control of Aspergillus spp and Penicillium spp. No phytotoxic effect of the fungicide and the vehicle agents was detected on the peanut seeds.

Controle químico de Fusarium moniliforme em sementes de milho: metodologia de avaliação e efeitos sobre a qualidade fisiológica

The objectives of this study were to evaluate the effect of light regimes on the mycelial growth of Fusarium moniliforme in fungicide-amended culture medium; to select the best light regime to detect F. moniliforme in treated corn (Zea mays) seeds and the variable to be used; and the effect of treatment on seed health and physiological quality. The fungicides evaluated were: fludioxonil + metalaxyl-m (three concentrations), difenoconazole, acibenzolar-S-methyl e captan + thiabendazole. For evaluation of mycelial growth, fungicides were added to the culture medium at three concentrations (100, 10 and 11 aeg/ml). Inoculated plates were incubated at 20±2 oC, under three light conditions: total darkness, white light and near ultraviolet light (12 h of light/12 h of darkness). In order to evaluate the effect of light on fungicide-treated seeds, a deep freezing test was carried out and seeds were incubated under the same conditions as the former test; seed health test was evaluated by measuring disease incidence and severity. Two seed samples were treated and submitted to seed health, germination, seedling emergence rates in greenhouse and cold tests. In vitro tests indicated that white light decreased the effect of the active ingredients fludioxonil + metalaxyl-m and captan + thiabendazole. The health test did not show this effect. Severity of the disease was found to be the most sensitive variable to distinct efficacy of fungicides in controlling F. moniliforme in corn seeds. The results found for both the two seeds samples suggested that: a) Fusarium moniliforme does not affect the physiological quality of corn seeds; b) the fungicide that controlled the pathogen in seeds was captan + thiabendazole, followed by fludioxonil + metalaxyl-m (97.2 g + 147.86 g/l); c) Pythium sp. was controlled by captan + thiabendazole and by fludioxonil + metalaxyl-m at the three concentrations.

Qualidade sanitária e germinação de sementes de Pterogyne nitens Tull. (Leguminosae - Caesalpinioideae)

Pterogyne nitens Tull. (Leguminosae Caesalpinioideae), wood species native to the Atlantic Rain Forest, is constantly used to extract timber. With the need to amplify the cultivation surface for trade, the interest in information about the quality and conservation of its seeds has increased. In spite of the great economic importance of this species, studies about the health quality of seeds are inexistent, mainly for native species. This paper aims to identify the occurence of pathogens associated in Pterogyne nitens seeds. The fungi were studied in a blotter test with and without freezing and symptoms in seedlings. The following fungi were found in seeds: Aspergillus sp., Penicillium sp., Fusarium moniliforme, Alternaria alternata, Rhizopus sp., Cladosporium sp. and Phoma sp. The largest occurence found was the fungi Aspergillus and Penicillium. The blotter test with freezing made it possible to identify two species of the potentially pathogenic Fusarium moniliforme and Alternaria alternata. Symptoms in seedlings were not detected.

Tratamento de sementes de pau-brasil com fungicidas: efeito na incidência de fungos, germinação e transmissão de fungos pelas sementes

ABSTRACT The objectives of this work were to evaluate the fungicidetreatment in fungi control in brazil-wood seeds and with captan,benomyl and carboxin+thiram in brazilian-wood seeds, verifyingthe fungi control and to make the transmission test of fungi byseeds. The results showed that the fungi found were Pestalotiopsis sp . , Cladosporium cladosporioides , Phoma sp. and Fusarium spp.All fungicides were efficient in the incidence of fungi, except for Fusarium spp. In relation to normal seedlings percentage thereLisboa-Padulla, T.; Moraes, M.H.D.; Menten, J.O.M.; Barbedo, C.. Brazil-wood seeds treatment with fungicide: effect in fungi incidence,germination and transmission of fungi by seeds. Summa Phytopathologica, v.35, n.2, p.148-150, 2009 Keywords: treatment, pathogenicity, Pestalotiopsis sp., Cladosporium cladosporioides. Palavras-chave adicionais: tratamento, patogenicidade, Pestalotiopsis sp., Cladosporium cladosporioides. RESUMO Os objetivos deste trabalho foram avaliar a eficiencia de fungicidasno controle de fungos em sementes de pau-brasil, efeitos na germinacaodas sementes e a transmissibilidade destes fungos para plântulas. Osresultados mostraram que os fungos incidentes foram

Relações entre ocorrência do Mal-de-Panama em bananeira da cv. Nanicão e nutrientes no solo e nas folhas

O presente trabalho teve como objetivo verificar se os sintomas incitados na bananeira cv. Nanicao, do subgrupo Cavendish, na regiao do Vale do Ribeira, estao relacionados com niveis de nutrientes no solo e nas folhas. Foram separadas 16 areas na regiao, sendo a metade com plantas sintomaticas e a outra com plantas sadias. Nessas areas, coletou-se a terceira folha de cinco plantas e o solo junto a essas mesmas plantas, nas profundidades de 0 a 20 cm e de 20 a 40 cm. Em ambas as profundidades do solo amostrado, niveis de Ca, Mg, PO-34, S e da capacidade de trocas cationicas (CTC) foram significativamente diferentes entre as areas, sendo que os valores baixos destes elementos estavam presentes nas areas contendo plantas sintomaticas. Em ambas as profundidades, o Mg, o Al e o H em relacao a CTC foram significativamente diferentes entre as areas, sendo que o valor baixo de Mg e alto de Al e H estava presente nas areas com plantas sintomaticas. O N, K e S nas folhas foram significativamente diferentes entre as areas. Estes elementos apresentaram valores baixos nas areas contendo plantas sintomaticas. Apesar de algumas quantidades de macronutrientes do solo e das folhas estarem presentes somente nas areas contendo plantas de Nanicao com sintomas semelhantes aos de fusariose, deve-se buscar comprovacao de uma possivel ocorrencia da raca 4 do patogeno no Vale do Ribeira.

Hábito de crescimento de Colletotrichum gossypii e C. gossypii var. Cephalosporioides em sementes de algodoeiro

Observacoes sobre o habito de crescimento de Colletotrichum gossypii e C. gossypii var. cephalosporioides em sementes de algodoeiro, inoculadas artificialmente e incubadas a 20-22°C durante cinco a sete dias, evidenciaram as seguintes caracteristicas: (a) em raizes: acervulos isolados ou em grupos, massa conidial cor branco-suja, alaranjada ou salmao (mais frequente), setas marrom-escuras, muitas vezes encobertas pela matriz gelatinosa; conidios produzidos tambem no micelio aereo ou nas extremidades das setas, onde ficam aderidos, formando pequenos aglomerados; (b) na superficie das sementes: conidios produzidos nos apices de setas que emergem diretamente do tegumento, ficando aderidos uns aos outros, formando cachos, semelhantes a cadeias, que sao vistos brilhantes sob a luz, em estereomicroscopio. As setas ferteis sao formadas tambem no micelio aereo que recobre as sementes, geralmente apos cinco dias de incubacao. Os acervulos com massa conidial raramente sao visiveis, exceto em sementes danificadas ou mortas. Como caracteristica de C. gossypii, observou-se que as sementes exibem, de modo geral, uma coloracao rosada, em decorrencia da abundante esporulacao; a ausencia ou escassez de micelio aereo e as setas curtas resultam em um crescimento rente ao tegumento e aspecto compacto. Comparativamente, nas sementes com C. gossypii var. cephalosporioides, as setas sao mais longas e menos densas; o micelio aereo com setas ferteis ocorre com mais frequencia, conferindo as sementes tonalidades acinzentadas e aspecto solto. A constatacao de setas ferteis em lesoes foliares de ramulose evidencia que, no campo, essas estruturas podem funcionar como autenticos conidioforos, desempenhando um importante papel epidemiologico, ao possibilitar a disseminacao dos esporos pelos ventos, a longas distâncias.

Relationship between IC50determined in vitro/in vivoand the fungicide rate used in the Field

Published data containing fungicide concentrations that control 50% (IC50) of a given fungus were analyzed. In the analysis we considered: (i) the IC50 determined in vitroand in vivofor a given fungicide and for a specific fungus; (ii) the concentration (g/ha) of active ingredient for the fungicide indicated to control a specific disease in the field; (iii) water volume of 120/L used in the spray; (iv) the fungicide a.i. concentration (mg/L) in 120 L volume; (v) and the ratio of the concentration used in the field with that determined in the laboratory. The analysis were performed by using IC50 data for DMIs, QoIs, a carbamate and a benzimidazol against the following fungi Bipolaris sorokiniana, Drechslera tritici-repentis, D. siccans, Fusarium graminearum, Puccinia triticina, Exserohilum turcicum, Phakopsora pachyrhiziand Corynespora cassiicola. The fungicide concentrations sprayed in the field were 33.9 (D. siccansand trifloxystrobin) to 500,000.0 (E. turcicumand iprodione) times higher than that determined in the laboratory. It was concluded that the IC50 was not related to the concentration used in the field and therefore should be used to compare the power among fungicides and to monitor the fungal sensitivity shift towards fungicides

Detecção de fungos em sementes de pau-brasil (Caesalpinia echinata) coletadas durante sua formação e dispersão

Brazilwood, also known as Pau-Brasil or Pernambuco, (Caesalpinia echinata Lam. Syn. Guilandina echinata (Lam.) Spreng.) is a Brazilian forest tree species which has important commercial uses but is at present listed as an endangered species by the International Union for Conservation of Nature (IUCN). Removal of brazilwood from the IUCN endangered species list is important roe its continued comercial utilization. Tropical forest species are propagated by several mechanisms but seeds are one of the main processes, which means that the health and physiological quality of the seeds of such species are important factors in their propagation. Our objective was to verify the incidence of fungi during the formation and dispersion of C. Echinata seeds because there are few accounts regarding the incidence of fungi in C. Echinata seeds and the reports that do exist do not clarify the point in seed formation when fungal infection occurs. We used the health-test to analyze seeds collected at different seed formation stages (post-anthesis and dehiscence). The main fungi detected being Cladosporium cladosporioides, Pestalotiopsis maculans and Epicoccum sp, with a lower incidence of Aspergillus sp, Fusarium sp., Nigrospora sp. and Penicillium sp. We found that C. cladosporioides and P .maculans were present in seeds since the beginning of seed formation, at the 40 days post-anthesis collection, and that the incidence of fungi increased with time reaching 100% in seeds with one and two days of dehiscence. We detected Fusarium sp. in seeds collected after dehiscence and the incidence increased while the seeds remained in contact with soil.

Efeito de fungicidas para controle da ferrugem asiática na qualidade de sementes de soja

The residual effect was assessed of fungicides to control Asian rust (Phakopsora pachyrhizi) in soybean seeds of the BRS-133 cultivar using 13 treatments (without fungicide, Priori + Nimbus, Aproach + Nimbus, Priori Xtra + Nimbus, Sphere + Aureo, Opera, Stratego + Aureo, Nativo + Aureo, Impact Duo + Oppa, Celeiro + Iharol, Battle + Oppa, Aproach Prima + Nimbus, Folicur ). The residual effect of the fungicides was analyzed by the germination test, accelerated aging, germination in sand and the seed health test. The treatments did not change the quality of the seeds and the treatment Battle + Oppa was efficient to control the pathogen Cercospora kikuchii on the seeds.