Blotter Test Research Articles

Physiological and Sanitary Quality in Cowpea Seeds Produced in Rio Grande Do Norte, Brazil

The importance of cowpea (Vigna unguiculata (L.) Walp.) to the Northeast region of Brazil is undeniable, it is a major crop in local family agriculture. As a result, the research aimed to evaluate the physiological and sanitary quality of local varieties of cowpea coming from the state of Rio Grande do Norte. The experiment was carried out at the Seed Pathology and Seed Analysis Laboratory, in Federal University of Paraíba, Campus II, Areia, Paraiba, Brazil. Six cowpea varieties (Baeta, Coruja, Sempre Verde, Epace 10, Feijão da Bahia and Pingo de Ouro) from rural Area of the municipality of Apodi, Rio Grande do Norte, Brazil.were evaluated  Seed physiological quality was evaluated by determining the first germination count (FGC), germination percentage (G%), seedling length (SL) and electrical conductivity (EC). The sanitary quality of the seeds was evaluated by the method of incubation in filter paper (blotter test). The experimental design was completely randomized, with 4 replicates. The Pingo de Ouro, Sempre Verde and Coruja varieties had germination percentages greater than the minimum standards required for commercialization, while the lower germination percentage and vigor of the Feijão da Bahia, Epace 10 and Baeta varieties may be associated with the presence of Aspergillus sp. and Penicillium sp.

Image analysis and health of Moringa oleifera seeds

Moringa oleifera Lam. (moringa) is a tree species with the potential for use in biofuel production. However, knowledge regarding the morphology and physiology of its seeds is needed to establish field production. The goals of the present study were to investigate the internal morphology of seeds by X-ray and to identify the fungal microorganisms present in the seeds. Two hundred seeds from two trees were analyzed. The morphological characterization of the seeds was performed using an X-ray chamber with an X-ray source operated at 22 kV for 14.8 s. The fungi were identified using the blotter test. The seeds were characterized as (a) full and well formed, (b) with internal space and poorly formed and (c) stained or damaged. The malformed seeds with an internal space showed the highest incidence (55%). The results indicated that X-ray tests are valid for the internal characterization of moringa seed morphology. The fungi Aspergillus niger, Aspergillus flavus, Alternaria sp., Fusarium sp., Penicillium sp. and Phomopsis sp. occurred in moringa seeds.

Influence of physiological and health quality on the vigor of cucumber seeds

ABSTRACT The physiological performance of seeds is related to their physiological quality and seed vigor, while their health quality may interfere with germination and early seedling establishment in the field due to the interaction of microorganisms associated with seeds. The study aimed to evaluate the physiological performance and health quality of cucumber seeds and to verify the relationship between these attributes. The physiological quality of cucumber seeds was evaluated by standard germination tests, first count of germination, controlled deterioration test, electrical conductivity test, seedling emergence, emergence speed index, and traditional accelerated aging and aging modified with saline for 48, 72, and 96 h. The health quality of cucumber seed lots was evaluated by blotter test. Stratification of cucumber seed lots by seedling emergence was similar to seedling emergence by controlled deterioration test, first count of germination, and electrical conductivity results. The cucumber seed lots evaluated showed high germination rates; however, lots 1 and 3 had a better performance in vigor tests than lots 2 and 4. Fungi detected in the blotter test were Alternaria sp., Aspergillus sp., Cladosporium sp., and Penicillium sp. Seed lots 2 and 4 had low vigor evaluated by seedling emergence and controlled deterioration, and showed a higher incidence of Penicillium sp. in the evaluation of health quality of seeds. The incidence of Penicillium sp. may negatively affect the vigor of cucumber seeds evaluated by seedling emergence and by controlled deterioration test.

Incidence of base rot and wilt, sanitary severity and influence about seed pathology by cultivars of common bean (Phaseolus vulgaris)

ABSTRACT: The objective of this work was to conduct a temporal evaluation of incidence of rot base and sanitary severity, and to relate the impact on the seed pathology of common bean cultivars. In the 2015-2016 harvest, in the city of Ipameri, Goiás, ten cultivars of common bean were evaluated (BRS Estilo©, BRS Pérola©, IPR Tangará©, IPR Tuiuiú©, IPR Uirapuru©, IAC Milênio©, Imperador©, IAC F3 R2©, IAC OTG© and IPR Campos Gerais©) and distributed into five blocks, totaling 40 experimental units. The incidence of wilt and base rot and sanitary severity were analyzed by taking ten random samples per block at 21, 28, 56, 63 and 69 days after planting. At the end of 120 days, a total of 20 plants were harvested per cultivar, and 250 seeds were harvested for application of the Blotter Test method. From 21 to 69 days after planting, the cultivars BRS Pérola© and IPR Campos Gerais© deserve to be highlighted for presenting the lowest incidence of wilt in the reproductive and vegetative cycles. The cultivar BRS Pérola© showed the lowest incidence of wilt and sanitary severity. In the analysis of harvested seeds, the cultivar BRS Pérola© presented high physiological quality for all evaluated parameters. On the other hand, Cramberry (OTG)© showed low physiological potential in germination and vigor tests.

Seeds of Calotropis procera Treated With Essential Oils of Copaifera langsdorffii Desf. and Syzygium aromaticum L.

The Silk Flower (Calotropis procera) is widely used by farmers in the Northeast region, due to the adaptation of the climatic and soil conditions of the semi-arid region, but the incidence of pathogens has reduced the physiological and sanitary quality standards acceptable for sexual propagation of these plants in the field. Thus, the objective of this research was to verify the effects of the Copaíba (C. langsdorffii) and Cravo (S. aromaticum) oils on the health and physiological quality of silk flower seeds (C. procera) harvested in the city of Tacima, PB. The treatments were constituted by Copaíba (C. langsdorffii) and Cravo (S. aromaticum) essential oils at concentrations of 0.5; 1; 1.5; 2% and the fungicide Captan® (240 g, i.a. 100 kg-1 seed). The control 0 (zero) corresponded only to the immersion of the seeds in distilled and sterilized water (ADE). In the evaluation of sanity, the method of incubation on filter paper (Blotter test) was performed, using twenty replicates of 10 seeds for each treatment. The physiological quality was evaluated by the germination test (G%), first germination count (FGC), germination speed index (GSI) and seedling dry mass (SDM). A microflora composed mainly of Alternaria sp. (52%), Fusarium sp. (70%), Helminthosporium sp. (40%), Cladosporium sp. (50%), Curvularia sp. (20%) and Nigrospora sp. (5%). The essential oils considerably reduced the percentage of fungi associated with silk flower seeds, but there was moderate phytotoxic effect under the germination and vigor of C. procera seeds.

RESPOSTADA IRRIGAÇÃO E DA APLICAÇÃO DE FUNGICIDAS SOBRE A QUALIDADE SANITÁRIA E PRODUTIVIDADE DE GRÃOS DE MILHO

The objective of this study was to evaluate the response of irrigation and foliar application of fungicide on the burned grain complex, fungal incidence (Blotter test) and grain yield of two maize hybrids. The experiments were conducted in the agricultural crop 2014/15, in Cruz Alta, RS. For both experiments, the treatments were arranged in a randomized block design and arranged in factorial scheme:2 (commercial hybrids) x 4 (3 fungicides and 1 control), with 4 replicates. In the laboratory, the grains were evaluated, as percentage of burned grains, grain sanity by Blotter test method, weight of one thousand grains and grain yield. There was influence of the use of irrigation, the hybrid, and the application of fungicides on grain yield and the incidence of burned grains and phytopathogenic fungi. Irrigation favored a higher incidence of burned grains and fungi Fusariumsp. and Aspergillussp. The hybrid BG7060HR provided a lower incidence of fungi and burned grains, parallel to a greater mass of a thousand grains and productivity when the fungicide Azoxystrobin + Benzovindiflupir was applied. The application of fungicides in the V8 stage of the culture reduced the incidence of fungi Fusariumsp.and Aspergillussp., especially the fungicide Azoxystrobin + Benzovindiflupir.

Seeds of weeds as an alternative host of phytopathogens

ABSTRACT: Weeds compete with agricultural crops for water, light, nutrients and space, besides having an extensive seed bank. However, another aspect to be considered relates to few studies pointing out weeds as hosts of phytopathogenic fungi. Many fungi, the main cause of diseases in plants, are known to use seeds as an efficient means of survival and dispersal. The objective of this work was to evaluate the health of weed seeds and the pathogenicity of fungi associated to plants of agricultural importance. The seeds were collected manually in Cerrado areas located in the municipality of Gurupi, Tocatins, Brazil. The blotter test method was used to evaluate seed health. The incidence of fungi was evaluated through an individual analysis of seeds using a stereoscopic and an optical microscope. The pathogenicity of fungi from weed seeds was evaluated by inoculation in plants of agronomic interest and, when pathogenic, we inoculated them in the host plant of the fungus. Weed seeds have been identified in fungi of the genus Alternaria, Aspergillus, Bipolaris, Cladosporium, Curvularia, Fusarium, Nigrospora, Papularia, Rhizopus and Pythium. The seeds of Acanthospermum australe, Bidens pilosa, Cenchrus echinatus, Digitaria horizontalis, Echinochloa crus-pavonis, Eleusine indica, Ipomoea sp., Pennisetum setosum, Sida rhombifolia, Spermacoce latifolia, Tridax procumbens and Vernonia polyanthes carry and disseminate fungi that, once inoculated, cause infection in plants of agricultural importance, such as Oryza sativa, Phaseolus vulgaris, Vigna unguiculata, Zea mays and Glycine max.

Combination of biocontrol bacteria for rice seeds microbiolization: incidence and transmission of Bipolaris oryzae, and plant growth

Abstract: Several fungi species are associated with rice seeds, mainly Bipolaris oryzae, since it can kill seedlings and reduce production. Thus, the objective of this research was to study the potential of pre-selected combinations of rhizobacteria [DFs-C4 (DFs185/DFs416/DFs418) and DFs-C5 (DFs306/DFs416/DFs418)], when compared to their use individually (DFs185, DFs306, DFs416, DFs418), besides DFs223, evaluating the effect on the incidence and transmission of B. oryzae, incidence of phytopathogenic fungi and in the initial growth after rice seeds microbiolization. Seeds of cultivars BRS Pelota and BRS Querência (four lots each) were immersed in suspension of these bacteria or in saline solution (control) under agitation (for 30 minutes at 10 ºC). The fungi incidence was evaluated on blotter test. The pathogen transmission was assayed in sterilized vermiculite and humid chamber at 25 ± 2 ºC. After 15 days, the severity of the symptoms and the plant growth were evaluated. For both cultivars, the best treatments were DFs185 and DFs306, reducing the fungi incidence, including B. oryzae, as well as its transmission to seedlings, resulting in seedling length increase. The combination of biocontrol bacteria, individually efficient, did not result in a lower fungi incidence, or a reduction in the transmission of B. oryzae to the seedlings or an initial increase in seedling growth. Therefore, these rhizobacteria are more efficient when used individually.

PATOGENICIDADE E TRANSMISSÃO DE FUNGOS ASSOCIADOS ÀS SEMENTES DE <i>Tectona grandis </i>L.f.

A produção de mudas de teca é realizada principalmente por sementes, que é um importante veículo de transmissão de diversos patógenos. Objetivou-se com este trabalho identificar e quantificar os fungos associados às sementes de teca, a patogenicidade desses microrganismos às mudas e a transmissibilidade semente-plântula. Para o teste de sanidade foram utilizadas sementes coletadas em Tocantins e outras adquiridas nos estados do Goiás (GO) e São Paulo (SP). Os tratamentos utilizados foram sementes desinfestadas e não desinfestadas, e sementes com e sem mesocarpo. O ensaio foi conduzido utilizando o método do papel de filtro (Blotter test). Para o teste de patogenicidade em mudas, foram utilizados os isolados de Fusarium sp., Botryodiplodia sp., Alternaria sp. e Plenodomus sp. Para a avaliação da transmissão de fungos via semente-plântula foram utilizadas sementes de cada local. Foram identificados os seguintes gêneros de fungos nas sementes: Fusarium, Trichoderma, Botryodiplodia, Aspergillus, Penicillium, Rhizopus, Cladosporium, Alternaria e Plenodomus. Foi observada maior ocorrência de fungos nas sementes provenientes dos estados de GO e SP. Fusarium foi o gênero fúngico com maior incidência nas sementes dos três estados. Apenas os gêneros Fusarium e Botryodiplodia foram patogênicos às mudas de teca. Houve baixa transmissibilidade semente-plântula, sendo que apenas o gênero fitopatogênico Fusarium foi transmitido.

Comparative growth of three Paecilomyces species on natural media and the possible pathological effects of their cultural metabolites on seed germination and radicle development of six economic crops in Ghana

Three Paecilomyces species from Cabi Science (UK) and P. carneus GHL 001 isolated from a local shrimps (Ghana) were tested for their radial growth characteristics on four different natural media, at temperatures of 15 °C, 18 °C, 20 °C and 25 °C using the culture plate radial method. The ability of culture metabolites of the test fungi raised in Yam Dextrose and Potato Dextrose Broths were tested on the germination capacity of six economic crops, using the conventional seed blotter test method. Radial growth of the fungal species showed similar growth pattern with optimum growth at 25 °C in most instances. The local P. carneus GH001 grew better and faster on all the media tested than P. carneus IMI133119 from the UK, underscoring the influence of environmental adaptation to physiological performance. The varietal differences in the response of the germinating seeds to the toxic metabolites can be ranked in decreasing order as follows: P. carneus IMI GHL 001 ˃ P. carneus IMI 133119 ˃ P. varioti IMI 40025 ˃ P. puntoni IMI 58415. To the best of our knowledge, this is the first report on the metabolites of P. carneus, P. puntoni and P. varioti adversely having pathological influence on germination and radicle development of cowpea, groundnut, soybean, okra, sorghum and cucumber in Ghana. Since these Paecilomyces species are used in some agricultural jurisdictions as entomopathogens for biocontrol of pests and diseases, environmental impact assessment is encouraged with the view of monitoring the soil bank for conidia of Paecilomyces which may affect the performance of crops in the field.

Physiological and sanitary quality of seeds de Acacia mearnsii De Wild. – Fabaceae

Acacia mearnsii has great economic importance and representation in the forestry sector. The aim of this study was to evaluate the physiological and sanitary quality of two lots of black wattle seeds. The seeds were obtained in Fepagro Forests and Mercosul seeds, respectively in the Santa Maria and Ijui counties in the Rio Grande do Sul state. For sanity used to detect fungus on potato-dextrose-agar (PDA) and substrate blotter-test (BT). For each test were four replicates of 25 seeds, evaluation, for both health testing was performed observing the fungal structures in stereoscopic and optical microscope. For the germination test, were used 200 seeds of each lot, divided into eight replicates of 25 seeds each, sowing was carried out in previously disinfected gerbox with 70% alcohol and sodium hypochlorite 1%, as substrate was used two filter paper sheets sterilized and moistened with distilled water. Fungi associated with seeds independent of utilized method were Penicillium sp., Cladosporium sp., Aspergillus sp. Mercosul’s lot, showed a greater number of healthy seeds on blotter-test (97.5%) and PDA (86%). The fungus with the highest incidence in the two methods compared (PDA and BT) was Cladosporium sp. in the Fepagro’s lot. For germination Mercosul’s lot showed 79.5% differing of Fepagro’s lot which showed 26.5%.

Óleos essenciais no tratamento de sementes de Phaseolus vulgaris L. durante o armazenamento

Os óleos essenciais apresentam metabólitos secundários com propriedades antibacteriana e antifúngica. Nesse sentido, objetivou-se com esse trabalho avaliar a incidência de fitopatógenos e a qualidade fisiológica de sementes de Phaseolus vulgaris L. cv. BRS Esplendor, tratadas com diferentes óleos essenciais em diferentes embalagens e tempos de armazenamento. Foram avaliados os óleos essenciais de canela (Cinnamomum zeylanicum), capim-limão (Cymbopogon citratus), cravo da índia (Syzgium aromaticum), erva-cidreira (Melissa officinalis), gengibre (Zingiber officinale), laranja-doce (Citrus sinensis), hortelã-pimenta (Mentha piperita.) e limão-taiti (Citrus aurantifolia), fungicida comercial e a testemunha, embalados em kraft ou pet. Aos 0, 60, 120 e 180 dias após o armazenamento das sementes, avaliou-se o teor de água; primeira contagem da germinação; porcentagem de germinação; índice de velocidade de emergência (IVE), emergência de plântulas, matéria seca e blotter test. Aos 120 e 180 dias após o armazenamento os tratamentos com óleos essenciais de C. aurantifolia e C. zeylanicum não afetaram a porcentagem de germinação das sementes quando acondicionadas em embalagem kraft. Entre as embalagens houve diferença significativa quando as sementes foram tratadas com os óleos essenciais de C. zeylanicum; C.sinensis e M. officinalis que reduziram a incidência do fungo do gênero Aspergillus spp. Os óleos essenciais de C. zeylanicum e S. aromaticum diminuíram a incidência de Penicillium spp., ambos armazenados em pet, tendo o óleo essencial de C. zeylanicum o comportamento semelhante ao fungicida comercial. A embalagem kraft foi mais eficiente em preservar a qualidade fisiológica das sementes tratadas de Phaseolus vulgaris L. do que a embalagem pet. No tempo zero de armazenamento, os tratamentos com C. sinensis e S. aromaticum promoveram efeito negativo sobre a qualidade fisiológica das sementes comparado a testemunha. O óleo essencial de C. citratus influenciou negativamente na porcentagem de germinação das sementes em relação aos demais óleos essenciais quando armazenado em saco kraft.

Development of Loop-Mediated Isothermal Amplification Assays for the Detection of Seedborne Fungal Pathogens Fusarium fujikuroi and Magnaporthe oryzae in Rice Seed.

Bakanae disease (caused by Fusarium fujikuroi) and rice blast (caused by Magnaporthe oryzae) are two of the most important seedborne pathogens of rice. The detection of both pathogens in rice seed is necessary to maintain high quality standards and avoid production losses. Currently, blotter tests are used followed by morphological identification of the developing pathogens to provide an incidence of infection in seed lots. Two loop-mediated isothermal amplification assays were developed with primers designed to target the elongation factor 1-α sequence of F. fujikuroi and the calmodulin sequence of M. oryzae. The specificity, sensitivity, selectivity, repeatability, and reproducibility for each assay was assessed in line with the international validation standard published by the European and Mediterranean Plant Protection Organization (PM7/98). The results showed a limit of detection of 100 to 999 fg of DNA of F. fujikuroi and 10 to 99 pg of M. oryzae DNA. When combined with a commercial DNA extraction kit, the assays were demonstrated to be effective for use in detection of the pathogens in commercial batches of infected rice seed of different cultivars, giving results equivalent to the blotter method, thus demonstrating the reliability of the method for the surveillance of F. fujikuroi and M. oryzae in seed-testing laboratories.

Sanity of corn grains as a function of genetic material

Diseases that occur in corn crops can cause great losses to farmers and consumers of its product and derivatives. So, was evaluated the sanity of maize grains in different genetic materials. The grains used were obtained from the crop of 2014/2015 on a farm in the city of Sorriso, State of Mato Grosso. For this, grain samples were collected from hybrids P3630H, 30F53YH, P2830H, and P3844H. The standard test (Blotter Test) allowed noticing the incidence of Aspergillus sp., Fusarium sp. and Penicillium sp. Data were submitted to analysis of variance and Scott-Knott test at 5% probability. In treatments with the resistant genetic material the genus with the highest incidence was Penicillium sp. (82%), followed by Fusarium sp. (68.75%) and Aspergillus sp. (15.25%). The hybrid with the lower incidence of Fusarium sp. was P2830H (59%). The hybrid with greater resistance to Aspergillus sp. and Penicillium sp. was P3844H (5 and 55%, respectively). The most susceptible hybrid to pathogens Aspergillus sp., Fusarium sp. and Penicillium sp. was 30F53YH (37, 79 and 94%, respectively). For the better sanitary quality of grains, based on the observed data, it is recommended to use the hybrid P2830H

Physiological and phytosanitary quality of common bean seeds used by small growers in Minas Gerais state, Brazil

The physiological and phytosanitary qualities of common bean seeds used on a small farming system depend on the cultural practices, drying system and storage conditions employed. The objective of this work was to evaluate eight lots of common bean seeds using germination, vigor andphytosanitary tests. The lots were produced in 2005 and 2006 in “Zona da Mata”, Minas Gerais State, Brazil, and analyzed for moisture content, germination quality, first germination count, seedling vigor, seedling emergence, electric conductivity, seedling dry weight, seedling length, hypochlorite test and blotter test. The experimental design was completely randomized with four replications. The mean seed moisture content from all lots was 8.4 %. Four lots were classified as high vigor, one as intermediate vigor and three lots as low vigor. The first germination count and electrical conductivity tests were the best for evaluating bean seed physiological quality. All seed lots were infested by fungi, mainly Alternaria, Cladosporium and Fusarium.

English

One hundred wheat (Triticum aestivum L.) accessions were selected on the basis of different geographical areas of Pakistan. Isolation and identification of seed born fungi were conducted according to standard blotter test and a total of five major seed borne fungi including Alternaria alternata, Aspergillus niger, Fusarium species, Drechslera species and Phytophthora species were isolated from the wheat seeds. The frequency of occurrence of these five seed born fungi was 49, 46, 42, 35, and 16%, respectively. Infection percentage varied from 0 to 90% in all 100 wheat accessions. Among the accessions, the highest infection (100%) of seed born fungi was recorded in 011185 and 011757 accessions while the lowest infection (10%) was recorded in 011415 accessions. Moreover, in accessions collected from Gilgit Baltistan and Azad Jammu Kashmir. Alternaria niger and Alternaria fusarium were dominant, while in Khyber Pakhtunkhawa province, A. niger was prevalent followed by A. alternata. In the case of Baluchistan province, the dominant seed born fungi was A. alternata followed by Drechslera spp. Similarly, in case of Punjab, the occurrence of A. alternata, Drechslera spp., Fusarium spp., and A. niger associated with seeds were similar. For accession collected from Sindh province, the dominant seed born fungi was A. niger and Drechslera spp. However, the Phytophthora spp. infection of wheat seeds accession of Baluchistan was the highest followed by wheat seeds accession collected from Gilgit Baltistan and AJK, Kpk and Punjab, whereas wheat seeds accessions collected from Sindh province were found to be free from Phytophthora spp. Key words: Bread wheat, screening, wheat germplasm, seed born fungi.

Effects of Some Plant Essential Oils against Fungi on Wheat Seeds

Abstract: Diseases, especially caused by seed borne fungi, are among the factors decreasing yield and quality of wheat. Common bunt is also an important seed borne disease of wheat worldwide. The objective of the study is to determine the effects of clove, ginger, mint, oregano and thyme oils on the fungal load of wheat seeds. In addition, effects of the oils on the germination rates of bunt spores were investigated. Blotter method was used to determine the effects of different concentrations (0.05 – 10%) of the oils on fungal load of wheat seeds. After incubation at 22°C for 7 days, seeds were investigated under stereomicroscope and fungi growing on the seeds were recorded. Germination rates of bunt spores were determined after incubation on water agar with different concentrations of oils. Highest doses of clove, mint and oregano oils totally inhibited the fungal growth on wheat seeds, but they also inhibited the germination of seeds. Lower doses failed to inhibit fungi on seeds, however they decreased or totally inhibited the germination of bunt spores. As a result, it was found that plant essential oils could be used against bunt disease of wheat as an alternative to fungicides. Key words: Triticum aestivum, seed-borne fungi, Tilletia spp., control, Blotter test, Germination rate.

Efficiency of Blotter test and agar culture medium to detect Fusarium graminearum and Pyricularia grisea in wheat seeds

Abstract: Seeds can be considered one of the most efficient forms to disseminate pathogens. Therefore, the use of healthy seeds is extremely important to establish a crop, and seed health testing must be performed to determine the seed sanitary quality. This study aimed to compare the efficiency of seed health testing to detect Pyricularia grisea and Fusarium graminearum in three samples of wheat seeds. Methods evaluated were Blotter test with freezing (BTF) and potato-dextrose-agar culture medium (PDA). The incubation temperatures were 20 ºC and 25 ºC. From each sample, a subsample was submitted to seed asepsis using hypochlorite solution (1%) and another analyzed without seed asepsis. The temperatures evaluated did not influence the detection of the pathogens. P. grisea incidence ranged from 4.5 to 17% with BTF without seed asepsis. The BTF with seed asepsis and PDA (with and without seed asepsis) presented pathogen incidence no higher than 1.5%. Moreover, results suggested that most part of P. grisea inoculum was presented externally on seed tissues. PDA medium was more efficient to detect F. graminearum, independently of seed asepsis. By this method, pathogen incidence ranged from 3 to 39%. F. graminearum incidence using BTF with seed asepsis varied from 0.5 to 1.5% and BTF without seed asepsis presented a pathogen incidence of 5.0 to 12.5%. The Blotter test with freezing was more efficient to detect P. grisea while the PDA medium was more efficient to detect F. graminearum.

Evaluation of inoculum potential of pathogens in seeds: relation to physiological quality and DNA quantification by qPCR

Abstract: Given what is already known in regard to seed health and the availability of molecular methods for detection of the pathogens Stenocarpella maydis and Stenocarpella macrospora in maize seeds, Colletotrichum gossypii var. cephalosporioides in cotton seeds, and Corynespora cassiicola in soybean seeds, the aim of this study was to evaluate seed vigor according to different inoculum potentials. The fungus isolates were inoculated on seeds by the technique of water restriction, through which different inoculum potentials are obtained, corresponding to times of seed exposure of 0, 24, 48, and 96 hours for maize and cotton seeds, and 0, 36, 108, and 144 hours for soybean seeds. The seeds were subjected to germination, electrical conductivity, health, and qPCR tests. Results of the blotter test showed that in most pathosystems, there was a higher incidence of the fungi with an increase in inoculum potential. A decrease in germination percentage was observed in all species as inoculum potential increased, as well as further degradation of seed membranes. The qPCR test confirmed that the most damaged seeds in the tests had higher presence of the pathogens.

The Efficiency of Noni (Morinda citrifolia L.) Essential Oil on the Control of Leaf Spot Caused by Exserohilum turcicum in Maize Culture.

The objective of this work was to evaluate the efficiency of noni essential oil on the control of Exserohilum turcicum, a causative agent of Exserohilum spot in maize culture. In the sanitary test 400 seeds were incubated using the blotter test method. For the transmissibility test, the fragments of damaged leaves of seedlings were removed and put into a potato, dextrose and agar (PDA) culture environment. To verify the pathogenicity, Koch´s postulates were performed. In the phytotoxicity test different concentrations of noni oil were applied in maize seedlings. E. turcicum conidia were submitted to different concentrations of noni oil. In the preventive and curative tests noni essential oils were applied before and after the conidia inoculation, respectively. The results revealed the presence of fungi of the genres Aspergillus, Penicillium, Rhizopus, Fusarium, and Exserohilum in the maize seeds. The pathogenicity of E. turcicum and also the transmission of this fungus from the seeds to the maize seedlings was confirmed. The inhibition of conidia germination was proportional to the concentration increase. The preventive application of noni essential oil was the most efficient on the control of Exserohilum spot.