ABSTRACT. Genetic variability of cassava (Manihot esculenta Crantz) in Brazil is wide, being this the result of natural and cultural selection during pre-and post-domestication of the species in different environments. Given the number of species of the genus found in the region (38 of a total of 98 species), the central region of Brazil was defined as the primary center of cassava diversity. Therefore, genetic diversity characterization of cassava accessions is fundamental, both for farmers and for plant breeders, because it allows the organization of genetic resources and better utilization of available genetic diversity. This research aims to assess genetic divergence of cassava accessions from the south-central region of the State of Mato Grosso, based on multi-categorical morphological traits. For this purpose, 38 qualitative and quantitative morphological descriptors were used. Genetic diversity was expressed by the genetic similarity index, with subsequent clustering of accessions by the modified Tocher's procedure and UPGMA. Of 38 descriptors, only growth habit of stem showed no variability. Tocher and UPGMA methods were efficient and corroborated on group composition. Both methods were able to group accessions of different localities in distinct group consistency.
, ORLANDO ANTÔNIO LUCCA FILHO 4 , FRANCISCO AMARAL VILLELA 4 RESUMO -Os resultados de pesquisas desenvolvidas demonstram a eficiência da mesa densimétrica no aprimoramento da qualidade de sementes de diversas espécies, evidenciando superioridade da qualidade fisiológica e sanitária das sementes coletadas nas posições superiores em relação às posições inferiores da zona de descarga da mesa. Considerando o reduzido número de trabalhos publicados sobre beneficiamento de sementes de hortaliças em especial sobre couve brócolis, cujas sementes apresentam diferenças no peso específico em virtude da desuniformidade de maturação das sementes, é importante estudar a influência da utilização da mesa densimétrica na classificação de sementes dessa espécie. O presente trabalho foi realizado com o objetivo de avaliar a qualidade fisiológica e sanitária de sementes de couve brócolis, beneficiadas em mesa densimétrica. As sementes inicialmente foram limpas em máquina de ar e peneiras e a seguir beneficiadas em mesa densimétrica. O eixo terminal de descarga da mesa densimétrica de 1,00m de largura foi dividido em quatro partes. Os tratamentos constituíram das frações obtidas no depósito da alimentação e nas partes: alta, intermediária alta, intermediária baixa e baixa, da zona de descarga da mesa densimétrica. As sementes de couve brócolis descarregadas na parte alta da zona de descarga da mesa densimétrica apresentaram qualidade fisiológica significativamente superior às sementes descarregadas nas partes baixa e repasse da fração intermediária baixa, sendo recomendável a remoção da fração direcionada para a parte baixa, visando o aprimoramento dos atributos fisiológicos e sanitários do lote.Termos para indexação: Brassica oleraceae var. itálica, vigor, beneficiamento, sanidade. PHYSIOLOGICAL AND SANITARY QUALITY OF BORECOLE BROCCOLIS SEEDS BENEFITED ON A DENSIMETRIC TABLEABSTRACT -The results of developed research demonstrate the efficiency of the densimetric table in the improvement of the quality of seed lots of diverse species, evidencing superior physiological and sanitary quality of the seeds in the upper positions in relation to the lower positions of the discharge zone. Considering the few reports on the improvement of vegetable seeds, especially borecole broccolis and, moreover the desuniformity of maturation of this species, that is reflected in the specific weight of the seeds, is important to study the influence of the use of the densimetric table on the performance of borecole broccolis seeds. The present study was carried out to verify the physiological and sanitary quality of borecole broccolis seeds, benefited by the densimetric table. The seeds had initially been cleaned in an air machine and sieved and then benefited on the densimetric
RESUMOA inoculação de fungos fitopatogênicos em sementes pela técnica da restrição hídrica é relativamente recente. Este trabalho objetivou avaliar o efeito de potenciais osmóticos (-0.4, -0,6 e -0.8) do substrato BDA, modificado por adição de sacarose, em interação com o tempo de exposição (46, 72 e 96 h), na infeção de sementes de trigo por Bipolaris sorokiniana. Foram analisadas a eficiência da infecção e a inibição da germinação durante e após a aplicação dos tratamentos. De acordo com os resultados, períodos de tempo superiores a 48 horas de exposição à colônia fúngica não foram inibitórios a germinação completa das sementes, a qual incrementou linearmente com o aumento do tempo de contato com o inóculo fúngico. A eficiência de infecção não diferiu para os potenciais osmóticos e tempo de exposição, variando de 0,53 a 0,92. No entanto, a capacidade germinativa das sementes após os tratamentos foi significativamente reduzida após o período de 48 horas de exposição das sementes ao substrato modificado contendo a cultura fúngica. Palavras-chave: potencial osmótico, sanidade de sementes, inoculação artificial. ABSTRACT Infection of wheat seeds by Bipolaris sorokoniana using a water restriction techniqueSeed inoculation with pathogenic fungi using the water restriction technique is relatively recent. This study aimed to verify the effect of osmotic potentials (-0.4, -0.6 and -0.8 MPa) of PDA substrate modified by the amendment of sucrose in interaction with the period of exposure (48, 72 and 96 h) of wheat seeds to colonies of Bipolaris sorokiniana. Infection efficiency and inhibition of seed germination during and after treatment were the variables analyzed. The results of this study show that an exposure period longer than 48 hours to the fungal colonies did not inhibit full germination of the seeds. The germination rate increased linearly as the exposure period to the fungal colony was increased. Infection efficiency was not affected by osmotic potential and exposure time, varying from 0.53 to 0.92. However, seed germination was significantly reduced after 48 hours of exposure to the fungal colonies.
-Stenocarpella maydis is one of the main fungi associated with maize seeds, being a causative agent of stalk and ear rot, a disease which causes considerable losses for crop-producing regions in Brazil. The organism is considered to be a pest, subject to sanitary standardisation in current programs of seed certification in the country. The aim of this study was to evaluate the transmission rate of the fungus from infected maize seeds. Seeds were inoculated with two isolates using a method of physiological conditioning, in which the seeds are kept in contact with colonies of the fungus for 24 (P1), 48 (P2), 72 (P3) and 96 (P4) hours. Two cultivars were used, one susceptible (C1) and one moderately resistant (C2), and the trial carried out at two temperatures (20 °C and 25 °C). The inoculated seeds were distributed individually into plastic cups containing substrate. The plants were evaluated daily for stand and the appearance of post-emergent symptoms. Based on the number of dead seeds, transmission rates reached a maximum of 90.5% at the P4 inoculum potential, this rate being greater than transmission rates achieved for symptomatic and asymptomatic infection in emerged plants. For the total transmission rate, transmission of the pathogen was seen at all inoculum potentials; these values varying from 25% for cultivar C2 at potential P1 and a temperature of 20 °C, to 93% for cultivar C2 at potential P3 and a temperature of 25 °C. RESUMO -Stenocarpella maydis é um dos principais fungos que se associam às sementes de milho, sendo um dos agentes causais da podridão do colmo e da espiga, que ocasiona perdas consideráveis em regiões produtoras desta cultura no Brasil. O referido organismo tem sido enquadrado como uma praga sujeita a padronização sanitária em programas de certificação de sementes vigentes no país. O objetivo nesse trabalho foi avaliar a taxa de transmissão do referido fungo a partir de sementes de milho infectadas. As sementes foram inoculadas com dois isolados pelo método de condicionamento fisiológico no qual as sementes são mantidas em contato com colônias do fungo por 24 (P1), 48 (P2), 72 (P3) e 96 (P4) horas. Foram utilizadas duas cultivares, uma suscetível (C1) e outra moderadamente resistente (C2) e o ensaio conduzido em duas temperaturas (20 e 25 °C). As sementes inoculadas foram distribuídas individualmente em copos plásticos contendo substrato. As plantas foram avaliadas diariamente quanto ao estande e aparecimento de sintomas em pós-emergência. Com base em sementes mortas, as taxas de transmissão alcançaram o percentual máximo de 90,5% para o potencial de inóculo P4, sendo esta taxa mais alta do que as alcançadas pelas taxas de transmissão para infecção sintomática e assintomática em plantas emergidas. Em relação à taxa de transmissão total, observou-se a transmissão do patógeno em todos os potenciais de inóculo, variando estes valores entre 25% para C2 no potencial P1 sob temperatura de 20 °C e 93% para C2 no potencial P3 sob temperatura de 25 °C.Palavras-chave: Fitopatologia. Patol...
Sorghum biomass is an interesting raw material for bioenergy production due to its versatility, potential of being a renewable energy source, and low-cost of production. The objective of this study was to evaluate the genetic variability of biomass sorghum genotypes and to estimate genotypic, phenotypic, and environmental correlations, and direct and indirect effects of seven agronomic traits through path analysis. Thirty-four biomass sorghum genotypes and two forage sorghum genotypes were cultivated in a randomized block design with three replicates. The following morpho-agronomic traits were evaluated: flowering date, stem diameter, number of stems, plant height, number of leaves, green mass production, and dry matter production. There were significant differences at the 1% level for all traits. The highest genotypic correlation was found between the traits green mass production and dry matter production. The path analysis demonstrated that green mass production and number of leaves can assist in the selection of dry matter production.
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