Ceratocystis fimbriata is a native, soilborne pathogen in South America that causes a lethal wilt disease on a broad range of economically important plants. Ceratocystis wilt on kiwifruit (Actinidia spp.) was first recognized in 2010 in the state of Rio Grande do Sul, Brazil. The genetic variation among kiwifruit isolates was analized to determine if a single introduced strain of the pathogen was responsible for the epidemic or if there was substantial genetic variation in the population, suggesting that the fungus was soilborne and indigenous to the region. We used 14 microsatellite (simple sequence repeat, SSR) markers to identify 18 genotypes of C. fimbriata among 76 isolates from eight kiwifruit farms. The 18 genotypes clustered into three groups based on UPGMA analysis of the microsatellite alleles. The largest group comprised 60 isolates of 11 closely-related microsatellite genotypes obtained from seven of the eight farms. These genotypes appeared to have originated from a single farm that had supplied cuttings for grafting to the other farms. The population of the pathogen from the farm that supplied the cuttings had the highest level of genotypic diversity and relatively high gene diversity, suggesting that this source population represented an indigenous, soilborne population. Phylogenetic analyses of the DNA sequences of the mating type locus (including portions of MAT1-1-2 and MAT1-2-1) placed the isolates into three groups, corresponding to the three microsatellite groups. Most of the isolates, including all the tested isolates from the farm that supplied the cuttings, had mating type gene sequences that were distinct from other Brazilian populations of C. fimbriata. A second group comprised isolates from one farm that had mating type gene sequences typical of Mata Atlântica (Rio de Janeiro and São Paulo) populations of C. fimbriata on Colocasia esculenta and Mangifera indica. Three farms purchased kiwifruit plants or rootstocks from commercial nurseries in Brazil as well as scions from the source farm, and some of the isolates from these farms were genetically similar to Eucalyptus isolates of C. fimbriata from Bahia and Minas Gerais, Brazil. The kiwifruit epidemic in Rio Grande do Sul is the southern-most report of C. fimbriata in Brazil, and the primary pathogen population on kiwifruit appears to be indigenous and originated from a single farm that distributed the pathogen in grafting material. In addition, commercial nursery stock was also implicated as sources of C. fimbriata genotypes. The disease is a major limiting factor for kiwifruit production in southern Brazil, and the results suggest that clean planting stock will be important to successful production.
RESUMOO objetivo deste trabalho foi determinar a qualidade fisiológica e sanitária de sementes de Senna multijuga (L. C. Rich.) Irwin & Barneby relacionada aos métodos de superação de dormência e à interferência na produção de mudas. As sementes foram submetidas aos seguintes métodos: imersão em água fervente, as sementes foram imersas em água, com temperatura de 100°C, até esfriar, por 24 horas; escarificação ácida, onde as sementes foram imersas em ácido sulfúrico (H 2 SO 4 ) a 90%, por 10 e 20 minutos, e testemunha (sem tratamento). Foram realizados os testes de sanidade, germinação, tetrazólio e avaliação da qualidade das mudas. O delineamento experimental foi inteiramente casualizado. Para a avaliação da germinação foi utilizado um esquema fatorial (4 X 2), com quatro métodos de superação de dormência X dois fotoperíodos, para os substratos rolo-depapel e vermiculita. A escarificação ácida constituiu-se no método mais eficiente para a superação da dormência das sementes de Senna multijuga. Penicillium sp. e Aspergillus sp. tiveram sua incidência aumentada quando o tegumento foi danificado pela escarificação ácida por 20 minutos. O controle de Fusarium spp. aumentou gradativamente com o aumento do tempo de exposição ao ácido sulfúrico.PALAVRAS-CHAVE: Espécies florestais; fungos; substrato; fotoperíodo. Overcoming of dormancy in the quality of seeds and seedlings: influence in the production of Senna multijuga (L.C. Rich.) Irwin & barneby ABSTRACTThe objective of this work was to determine the physiological and sanitary quality of Senna multijuga seeds related to the methods of dormancy overcoming and the influence on the seedlings quality. The seeds had been submitted to the following methods :immersion in water fervent, the seeds had been immersed in water, at 100°C, until cooling for 24 hours; acid escarification, where the seeds had been immersed in sulfuric acid (H 2 SO 4 ) 90%, for 10 and 20 minutes, and control (without treatment). The tests of sanity, germination and tetrazolium had been carried through, and were evaluated the quality of the seedlings. For the germination of the evaluation an factorial project was used (4 X 2), with four methods of dormancy X two light periods, for substrate paper and vermiculite. The acid scarification consisted in the method most efficient for the dormancy of Senna multijuga seeds. Penicillium sp. and Aspergillus sp. they had for its increased incidence when the seed coast was damaged by the acid scarification for 20 minutes. The control of Fusarium spp. increases gradual with the increase of the time of sulfuric acid exposition.
O objetivo deste estudo foi definir a metodologia mais adequada para a realização do teste de tetrazólio em sementes de Ceiba speciosa (A. St. -Hil.) Ravenna -Malvaceae (paineira). Duas amostras de sementes foram utilizadas, para as quais, inicialmente, determinaram-se o teor de água e a germinação. Para o teste de tetrazólio foram testados dois tempos de exposição, três e quatro horas, e três concentrações da solução de tetrazólio, 0,1, 0,5 e 1%. O delineamento estatístico foi inteiramente casualizado em esquema fatorial 2x2x3 (amostras x tempos x concentrações) com quatro repetições de 25 sementes. A comparação das médias foi feita pelo teste de Duncan a 5% e após foi realizada análise de correlação entre os resultados do tetrazólio e de germinação. Embora a concentração de 0,1% de tetrazólio tenha permitido a visualização de uma maior porcentagem de sementes viáveis, para ambas as amostras e ambos os tempos de exposição, apenas a concentração de 0,5% com quatro horas de exposição, se correlacionou positiva e significativamente com a germinação para ambas as amostras. Portanto, o teste de tetrazólio para sementes de paineira deve ser realizado utilizando-se para coloração a solução de tetrazólio a 0,5%, por quatro horas. Palavras-chave: Paineira, viabilidade, sementes florestais AbstractThe nutritional state of star fruit seedlings must be adequate for a successful field implementation. The The objective of this research was to define the tetrazolium test methodology for Ceiba speciosa seeds. Two C. speciosa seeds samples were used and, for each of these, it were determinate the moisture content and germination. For the tetrazolium test it were tested two periods of tetrazolium solution exposition (three and four hours), and three tetrazolium solutions concentrations (0.1, 0.5 and 1.0%). All the treatments were submitted to the temperature of 40°C in dark. The statistical design was completely randomized, in a factorial scheme 2x2x3 (samples x periods x concentrations) with four replications of 25 seeds. The means comparison was by the Duncan test at the 0.05 level of probability and were done correlation tests between tetrazolium and germination tests. Although the tetrazolium solution 0.1% allowed identify high percentages of viable seeds for both samples and periods, only the 0.5% concentration for four hours had a positive and significant correlation with the germination for both samples. Thus, the tetrazolium test for Ceiba speciosa seeds should be realized with the tetrazolium solution concentration of 0.5%, for four hours.
Os objetivos deste trabalho foram: avaliar a qualidade fisiológica de sementes de cedro (Cedrela fissilis), procedentes de localidades do sul do Brasil, através de testes de vigor e avaliar diferentes tratamentos nas sementes para controle de patógenos e para promoção da germinação da espécie. Para tanto, foram utilizadas seis amostras com procedências dos Estados do Rio Grande do Sul, Santa Catarina e Paraná, as quais foram submetidas à determinação de teor de água, teste de germinação e primeira contagem, envelhecimento acelerado (testando períodos de exposição às condições de envelhecimento), emergência em viveiro e tratamento de sementes. Os tratamentos utilizados para controle de patógenos foram: testemunha (T0); físico com calor seco a 70°C±3°C por 48 horas (T1); extrato aquoso de alho (Allium sativum) (T2); biológico à base de Trichoderma spp. - Agrotich Plus® (T3); e químico com fungicida protetor Captan (T4). A germinação variou de 56 a 87%; o período de 48 h sob temperatura de 41 °C foi o mais eficiente para estratificar as amostras em níveis de vigor; a emergência variou de 51 a 88% e as variáveis de desempenho de plântulas analisadas conseguiram estratificar as amostras em níveis de vigor. Quanto ao tratamento de sementes, o calor seco e o tratamento à base de extrato de alho se mostram eficientes no controle de microrganismos em semente de cedro, sem prejuízos ao vigor destas.
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