Dematium Var Research Articles

Effect of the Storage Period and Fungicide Treatment on the Physiological and Sanitary Quality of Soybean Seeds

This study evaluated the effect of storage period on the physiological and health quality of soybean seeds. The experiment was arranged in a factorial scheme (4 x 2 x 2) with four periods of storage (0, 2, 4 and 6 months), two soybean cultivars (‘BRS Pintado’ and ‘MSOY 8866’) and treated and untreated seeds with the formulated mixture of active ingredients pyraclostrobine (25 g i.a L-1) + Methyl-Thiophanate (225 g i.a L-1) + fipronil (250 g i.a L-1) in a 0,1 L.ha-1 dosage of the commercial product. Concerning health, there was a reduction of Aspergillus spp., Cercospora kikuchii, Colletotrichum dematium var. truncata and Fusarium spp fungus when periods of storage were increased independently if storage interactions occurred due to cultivar, treatment and/or all analyzed factors. cv. ‘BRS Pintado’ stood out by presenting lower results on the occurrence of fungi. The isolated cultivar factor presented a significant result concerning the physiological quality and c.v. ‘BRS Pintado’ showed better results in the variables: germination of seeds from the speed aging test, germination, shoot lenght from the speed emergence test, and both shoot dry matter and root dry matter of germination. There was an interaction for the speed emergence index variable between storage versus cultivar, in which cv. ‘BRS Pintado’ achieved better average results in all periods of storage. The storage factor alone was significant for shoot length of plants from the speed emergence index, the shoot plant dry matter from the emergency speed index, root dry matter of seedling germination and germination of seeds subjected to accelerated aging. The isolated treatment factor was significant in the germination variable and the untreated seeds showed better results in relation to the treated ones. However, the difference of these values would not be significant at the field. Treated seeds showed better results compared to untreated ones in most of the analyzed variables and their association with seeds storage did not affect the physiological quality evaluation during six months of evaluation, enabling the maintenance of the health quality of seeds.

Determinação do estádio de dessecação em soja de hábito de crescimento indeterminado no Mato Grosso

For cultivars with indeterminate habit, there are no reports of the most appropriate period to conducted burndown in pre-harvest. The study aimed to evaluate the influence of burndown on three different times over physiological and sanitary quality of seeds and agronomic characteristics of SYN-9074 RR cultivar with indeterminate habit, in three areas simultaneously. It was used a randomized complete block design with four replications, and joint analysis were conducted for the three distinct areas. Treatments refer to the application period of diquat (0.3 kg ha -1 ), or better, in soybean plants at maturation stages R6.5 (fully formed seeds, pods 50% yellow and 50% green), R7 (pods 70% yellow, with a fully mature pod on the main stem) and R7.5 (90% yellow pods) and a check without herbicide. Germination test, dry mass of dossel and little root part, shoot length and little root, sanitary condition and mass of 1000 seeds and yield were evaluated. The period more adequate to accomplish burndown in pre harvest of SYN-9074 RR cultivar with indeterminate habit was with plants showing 90% of yellow pods, or maturation period R7.5, that provided higher yield and lower incidence index of Phoma sp., Colletotrichum dematium var. truncata and Fusarium sp. fungi.

Levantamento de doenças na cultura da soja, Glycine max (L.) Merrill, em municípios da região Oeste do Estado do Paraná

A survey was carried out in the western region of Parana, Brazil, to assess the occurrence and to identify diseases afflicting soybean, Glycine max (Leguminosae-Faboideae), particularly those of economic importance. Plant samples were collected from 126 commercial soybean crops growing in nine administrative areas: Marechal Cândido Rondon, Quatro Pontes, Toledo, Pato Bragado, Santa Helena, Nova Santa Rosa, Mercedes, Palotina and Terra Roxa. Samples were taken from plants showing symptoms of diseases proper to the crop. Disease symptomatology was recorded, and standard laboratory procedures, including preparation of permanent microscope slides with fungi, nematodes and fungus culture, on media culture PDA, were done to determine the causal agent of the diseases recorded. Perinneal pattern and analysis of esterase phenotype were compared for the identification of Meloidogyne spp. nematodes recovered during the survey. Twenty-one causal agents of diseases in soybean were identified during this survey. They consisted of fifteen fungi, one bacterium, one virus and four nematode species. The most widespread were Downy Mildew, Powdery Mildew, Bacterial Blight and the root-knot nematodes M. javanica and M. incognita nematosis. In a complementary study samples were collected from commercial seed lots of 16 soybean cultivars. Some lots were found to be contaminated by Fusarium sp., Colletotrichum dematium var. truncate and Phomopsis sp

EFEITO DO TRATAMENTO QUÍMICO DE SEMENTES DE SOJA (Glycine Max L.) (Merril) SOBRE SUA EMERGÊNCIA

Aiming to test the effect of different fungicides on emergence and productivity of soybeans, were used chemical products captan, dichlofluanide and thiram at different dosages. The experiment was made in the experimental fields of Agronomy School-UFG, using variety EMGOPA 301 with high level of infection by fungi (Colletotrichum dematium var. truncata, Phomopsis sp., Penicillium sp., Aspergillus flavus and Fusarium semitectum). The results indicated that all fungicides used at different dosages were efficient in levels statistically significant relatively to testimony. Among the fungicides was not observed the same fact, the best results attained with crescent dosages of the products utilized.

Sobrevivência de patógenos associados a sementes de soja armazenadas durante seis meses

Sementes contaminadas ou infectadas no campo podem ter sua sanidade alterada durante o armazenamento, pela perda da viabilidade dos patógenos. O objetivo do presente trabalho foi verificar o efeito do armazenamento na qualidade sanitária de sementes de soja. Variedades de soja BRS 133, MSoy 6101, Conquista e Liderança foram inoculadas, no campo, por pulverização com suspensão de esporos de dois isolados de Colletotrichum dematium var. truncata e Phomopsis sojae. Após a colheita foram realizados testes de sanidade, sem e com desinfestação superficial das sementes com hipoclorito de sódio a 1% por 3 min. As sementes foram armazenadas em câmara fria, por seis meses, e testes de sanidade foram novamente realizados. Os resultados do trabalho permitem concluir que o armazenamento das sementes de soja contaminadas por fungos em câmara fria, por um período de seis meses, diminuiu a incidência de Phmopsis sojae e Colletotricum dematium var. truncata.

Efeito de Colletotrichum dematium var. truncata e Phomopsis sojae na qualidade sanitária e fisiológica de sementes de soja

Tem sido atribuído a vários patógenos reduções na qualidade de sementes de soja. Com o objetivo de avaliar o transporte dos fungos pelas sementes provenientes de plantas de soja, artificialmente inoculadas em condições de campo com dois isolados de Colletotrichum dematium var. truncata e um isolado de Phomopsis sojae, e seu efeito sobre a qualidade sanitária e fisiológica das mesmas, quatro variedades de soja (BRS 133, MSoy 6101, Conquista e Liderança) foram manualmente semeadas no campo, e as plantas obtidas foram inoculadas com C. dematium var. truncata isolado 1 e isolado 2, e P. sojae. A testemunha permaneceu sem inoculação. As sementes foram colhidas manualmente e submetidas a testes para avaliação da sanidade, teor de água, peso de 100 sementes, germinação em papel e emergência em areia. A desinfestação das sementes com hipoclorito de sódio a 1% por 3 minutos diminuiu a incidência dos patógenos nas mesmas. As sementes apresentaram uma alta infecção por Fusarium spp.. Phomopsis sojae foi encontrada em todos os tratamentos, e sua incidência nas sementes esteve relacionada com a incidência de Fusarium sp.. Há diferença na patogenicidade entre isolados de C. dematium var. truncata, sendo o isolado 1 o mais patogênico, com destaque para a variedade Liderança (25% de infecção por C. dematium var. truncata). Fusarium sp. influenciou negativamente a germinação de sementes da variedade MSoy 6101, independente do tratamento, e C. dematium var. truncata afetou negativamente a germinação das sementes das variedades Conquista e Liderança. Os valores de emergência em areia apresentaram-se significativamente superiores à germinação em papel, para as variedades MSoy 6101, Conquista e Liderança.

Efeito de Colletotrichum dematium var. truncata e Cercospora kikuchii na germinação de sementes de soja

A antracnose, causada por Colletotrichum dematium var. truncata, é a principal doença da soja que afeta a fase inicial de formação das vagens, podendo causar a morte das plântulas. Cercospora kikuchii é o fungo causador da doença mancha púrpura nas sementes de soja, responsável por severas reduções no rendimento e na qualidade das sementes. O objetivo deste trabalho foi determinar o tempo mais apropriado para infecção das sementes de soja por C. dematium var. truncata e C. kikuchii, para posterior avaliação dos danos causados pelo fungo na germinação. Tais fungos foram cultivados em meio BDA. As sementes de soja cultivar MSOY 6101 foram colocadas sobre meio contendo o patógeno C. dematium var. truncata por 0 (testemunha), 4, 16, 24, 32 e 40h. As sementes da cv. CD 208 foram inoculadas com C. kikuchii pelos mesmos períodos citados, com adição de 48 e 56h. Após os respectivos tempos de contato, as sementes foram submetidas ao teste de sanidade (papel de filtro), com duas variações, sem e com assepsia superficial (hipoclorito de sódio 1% por três minutos). Determinado o tempo mais adequado de infecção, outras sementes foram infectadas pelo patógeno e, posteriormente, foram realizados testes de germinação em papel e areia com uma mistura de sementes sadias (colocadas sobre o meio BDA) e sementes inoculadas, resultando em lotes com 0, 20, 40, 60, 80 e 100% de sementes infectadas. O tempo de incubação de 40 e 56 horas para C. dematium var truncata e C. Kikuchii, respectivamente são suficientes para obtenção da totalidade das sementes infectadas. C. Kikuchii não prejudica a germinação das sementes.

Ethylene production and toxigenicity of methionine and its derivatives with riboflavin in cultures of Verticillium, Fusarium and Colletotrichum species exposed to light

Ethylene was produced by Verticillium dahliae Kleb. grown in liquid Czapek's medium. The rate of ethylene production was enhanced by light but was not affected by shaking or the growth rate of the cultures. L‐, D‐ and DL‐methionine, DL‐ethionine and a‐keto‐y‐methylthiobutyric acid (KMBA) were good substrates for ethylene production. KMBA may be an intermediate in ethylene production and it appears to be degraded to ethylene either enzymatically by peroxidase or photochemically in the presence of riboflavin. Addition of riboflavin or briefly heating the cultures to 100°C enhanced ethylene production greatly, while the addition of sodium azide, potassium cyanide and catalase were very inhibitory. The SS4 (non‐defoliating) pathotype of V. dahliae produced significantly more ethylene (up to 108.4 nl ethylene h1 from 20 ml‐10‐day‐old cultures) than did the T9 (defoliating) pathotype with all substrates tested. The results suggest that the in vitro rate of ethylene production is not related to the relative virulence of pathotypes of V. dahliae on cotton. A number of Verticillium species, Fusarium oxysporum f. sp. vasinfectum and Colletotrichum dematium var. truncatum were able to produce ethylene in liquid Czapek's medium containing 1 mM L‐methionine under continuous light. Riboflavin, although highly stimulatory to ethylene production, caused a fungicidal reaction to all the fungi tested in Czapek's medium containing L‐methionine under continuous light. The fungicidal effect of the riboflavin‐methionine‐light combination occurred at concentrations of riboflavin and methionine less than 1.33 μM and 0.5 mM, respectively. No fungicidal activity was detected when the cultures were grown in total darkness or when either methionine or riboflavin was omitted from the culture medium.

Effect of paraquat on soybean pathogens and tissues

Alternaria sp., Colletotrichumdematium var. truncatum, Macrophomina phaseolina and Phomopsis sp., isolated from soybean ( Glycine max ) seeds, differed in tolerance to paraquat as measured by mycelial production, linear mycelial growth, spore germination and glucose consumption. Alternaria sp. was most sensitive to paraquat; Phomopsis sp. least sensitive with M. phaseolina being intermediate. The growth of C. dematium var. truncatum was variable. Colonization by M. phaseolina and Phomopsis sp. of soybean stem pieces treated with different concentrations of paraquat and then surface sterilized, was inhibited and stimulated, respectively. Paraquattreated soybean pods released electrolytes and amino acids. These results are discussed in relation to the occurrence of C. dematium var. truncatum and Phomopsis sp. on soybeans sprayed with paraquat in the field and the use of paraquat in the laboratory for the detection of latent colonization by these and other fungi.

Título en español

En 1975 tres subcultivos de Colletotrichum dematium var. truncata se obtuvieron de sojas sembradas en las regiones central y meridional de Illinois. Estas se designaron Cd-1, Cd-2 y Cd-3. Los tres subcultivos produjeron conidios curvados que medían entre 17.8 y 23.3 µ de largo y de 3.2 a 5.1 de ancho. La tasa de crecimiento y la producción de esporas de los tres variaron: el Cd-3 fue el que más esporas produjo por cm2 y el Cd-2 el que produjo la colonia más grande a 25° C. El Cd-1 fue tolerante al benomyl in vitro y presentó un crecimiento radial uniforme en agar de papa y dextrosa modificado con 1 a 350 µg/ml de benomyl comercial. Los subcultivos Cd-2 y Cd-3 presentaron una curva bimodal de crecimiento. Colletotrichum glycine y C. musae fueron sensibles al benomyl.

Effect of prism generated discreet wavelengths of light on germination and post-germination development of Colletotrichum dematium var circinans (Berk.) v. Arx

Spores, harvested from 8 da old colonies ofColletotrichum dematium varcircinans (Berk.) v. Arx, were placed on slides under shimmed coverslips and subjected to 10 min irradiation with wavelengths of light ranging from 400 to 750 nm. Controls consisted of spores exposed to 10 min of fluorescent or tungsten light, or to continuous dark. Germination, and production of sessile and non-sessile appressoria, and germ-tubes was monitored. In addition position of germ-tubes on spores was noted and germination types were classified by numbers of germ-tubes and sessile and non-sessile appressoria produced. When compared to dark controls certain wavelengths, 400, 450, 600 and 650 nm, appeared to be inhibitory to germination and post-germination development, while others, 500, 550 and 750 nm, appeared to be stimulatory. Spores irradiated with some of the wavelengths (550, 700, 750 nm) that affected other responses produced the smallest percentage of sessile appressoria (approx. 10%). Placement of germ-tubes was not affected by treatment. More germ-tubes were produced from spore bottoms (53%) than tops (32%), and tips (15%). The fewest number of germ-tubes was produced from spore centers and from one tip. Thirteen germination types were noted. About 53% of spores germinated with one germ-tube, one non-sessile appressoria, and no sessile appressoria. The remaining 47% were distributed throughout the remaining 12 types, and ranged from 21% to less than 1% of the total. Treatments did not affect this distribution.

Spore age and coverslip placement affects germination and post-germination development of Colletotrichum dematium var circinans

Spore suspensions from young (10–14 da; young spores) and old (4 mo; old spores) colonies of PColletotrichum dematium var circinans were placed on slides. Coverslips were left off, placed on in the normal manner, or supported on shims. Slides were placed in moist chambers and incubated in light or dark for up to 48 hrs. Germination and post-germination development were studied. Shimming had some beneficial effect on germination, especially for old spores in dark. In general, more germ-tubes and appressoria were produced on spores under shims than spores with other coverslip treatments. By 48 hrs more old spores under shims germinated, and greater numbers of germ-tubes and appressoria were produced than on other old spores under different coverslip treatments. However, numbers produced were lower than those predicted for comparably treated young spores. Spore age, incubation regime, and placement of coverslips did not affect germ-tube initiation. For all treatments more germ-tubes were initiated from spore tops than bottoms or tips. Fewer germ-tubes were initiated from spore centers than other locations on tops and bottoms, and from both tips than one tip. Approximately 26 % of all appressoria were produced sessile. A higher percentage of sessile appressoria were produced on old spores (80 %) than on young spores (20%).

Effect on germination and post-germination development of Colletotrichum dematium var circinans due to light and dark incubation and coverslip placement

Light regime was not a major factor in germination of spores of Colletotrichum dematium var circinans. Number of germ-tubes and appressoria formed were affected by incubation regime and coverslip placement. Most germ-tubes and appressoria were produced on spores under shimmed coverslips. Light incubation favored germ-tube production and dark incubation favored appressoria production. Predicted time to 100% germination was affected by treatments. Shortest times were predicted for light incubated spores under shimmed coverslips. Longest times were predicted for non-coverslipped spores. A significant number of appressoria were produced sessile on spores. Most sessile appressoria were produced on dark incubated spores. Approximately 56 % of all spores germinated, and approximately 60% of all germ-tubes and appressoria were produced on these spores which were situated closest to coverslip or droplet edges. Placement of germ-tubes on spores was not affected by treatments. However, percentages of germ-tubes, initiated from various areas of spores, were significantly different. This variation appears to be due to factors internal to spores.