Abstract BRS Boitatá and BRS Ocauçu cassava cultivars for the industry have high root and starch yields and high starch contents in first-cycle and second-cycle harvests, medium tolerance to the main diseases, adequate architecture for mechanized planting and stability in starch contents. firstcycle first cycle secondcycle second harvests diseases

Abstract Twenty six sweet cassava clones were evaluated in two agricultural years, in randomized block design, with 3 replications and plots with 25 plants. The harvests were at 12 months after planting, in both years. The traits evaluated were root yield (RY), dry matter content (DMC), total carotenoids content (TC), β-carotene content (BC), trans-β-carotene content (TrBC) and total cyanide content (TCy). Genotype was significant (P<0.05) in all traits. Broad-sense heritability estimates at the plot level ( h m g 2 ) ranged from 77% (RY) to 93% (TC and TrBC), while the accuracy ranged from 0.88 (RY) to 0.96 (BC and TrBC). The genetic correlations among TC, BC and TrBC were high (0.96 to 0.99) and significant, and the genetic correlations involving these traits and TCy were negative. These results demonstrate the existence of great genetic variability in characteristics important to cassava biofortification and, consequently, great perspectives in the breeding for this purpose. years design plants 1 planting RY, RY , DMC, DMC (DMC) TC (TC) βcarotene β carotene BC, (BC) transβcarotene trans (TrBC TCy. . (TCy) P<0.05 P005 P 0 05 (P<0.05 Broadsense Broad sense 77 (RY 93 TrBC, TrBC) 088 88 0.8 096 96 0.9 TrBC. (0.9 0.99 099 99 negative consequently purpose (DMC (TCy P<0.0 P00 (P<0.0 7 9 08 8 0. 09 (0. P<0. P0 (P<0. (0 P<0 (P<0 P< (P< (P

RESUMO O objetivo desse trabalho foi avaliar desempenho agronômico, tempo de cozimento e conservação pós-colheita de raízes de clones de mandioca de mesa, para selecionar aqueles superiores à testemunha Manteiga, na região do Baixo Sul do estado da Bahia. O delineamento foi em blocos casualizados e em esquema de parcelas subdivididas, com três repetições. Onze clones foram avaliados aos 10 e 12 meses após o plantio. Na média das duas colheitas, BRS Kiriris e Saracura tiveram produção total de raízes (39,85 e 33,91 t ha−1, respectivamente) e produção de raízes comerciais (26,54 e 26,71 t ha−1) superiores, comparados ao Manteiga (produção total de raízes: 28,06 t ha−1, produção de raízes comerciais: 16,95 t ha−1). Entretanto, ambos tiveram tempo de cozimento (26,76 e 28,30 min, respectivamente) maiores que o do Manteiga (23,89 min), e BRS Kiriris foi instável com relação à porcentagem de cozimento entre 10 (91,67%) e 12 meses (50%). BRS Aipim Brasil, 2003 14-11, BRS Kiriris, Eucalipto, Saracura e Manteiga foram mais tolerantes à deterioração fisiológica de pós-colheita. Embora alguns dos clones avaliados tenham apresentado bom desempenho nas características avaliadas, analisando-se o conjunto de características, nenhum deles apresenta superioridade suficiente para ser indicado como um potencial substituto do Manteiga, cultivado na região do Baixo Sul do estado da Bahia.

ABSTRACT The objective of this work was to evaluate the agronomic performance, cooking time and postharvest conservation of roots of sweet cassava clones, to select those superior to the Manteiga variety control, in the Baixo Sul region of Bahia state. A randomized block design in split plot scheme, with three replications was used. Eleven genotypes were evaluated at 10 and 12 months after planting. Considering the mean of two harvests, BRS Kiriris and Saracura showed total root yield (39.85 and 33.91 t ha−1, respectively) and commercial root yield (26.54 and 26.71 t ha−1) that are higher compared to Manteiga (total root yield: 28.06 t ha−1, commercial root yield: 16.95 t ha−1). However, both had cooking time (26.76 and 28.30 min, respectively) higher than that of Manteiga (23.89 min), and BRS Kiriris was unstable regarding the cooking percentage between 10 (91.67%) and 12 months (50%). BRS Aipim Brasil, 2003 14-11, BRS Kiriris, Eucalipto, Saracura and Manteiga were more tolerant to postharvest physiological deterioration. Although some of the evaluated clones presented good performance in the evaluated traits, by analyzing the set of traits, none of them shows sufficient superiority to be indicated as a potential substitute for Manteiga, grown in the Baixo Sul region of Bahia state.

Abstract: The cultivar BRS 420 has superior starch yields in early and late harvest, moderate resistance to the main diseases of the crop, adaptation to mechanized planting and to the no-till system, as well as rapid formation of soil cover (which assists in weed control). It represents an alternative for cassava growers in Paraná and Mato Grosso do Sul.

Resumo: O objetivo deste trabalho foi avaliar a resistência de populações transgênicas de mamoeiro (PTPs) ao vírus da mancha anelar do mamoeiro [Papaya ringspot virus-P (PRSV-P)]. Plantas transgênicas 'Sunrise Solo' foram produzidas com o gene da proteína da capa viral PRSV-P, e o PRSV foi inoculado mecanicamente nas plantas em casa de vegetação. A presença do gene CP/PRSV e a homozigose foram avaliadas por reação em cadeia da polimerase. As plantas selecionadas e o controle 'Sunrise Solo' foram transplantados para o campo, para avaliações agronômicas. As plantas avaliadas em casa de vegetação apresentaram resistência entre 96,3 e 5,8%, sem variação nos sintomas. As PTPs 1/6, 1/7, 1/9, 1/10, 1/15, 2/38, 2/41, 2/56, 2/65, 3/27, 3/46, 3/48, 4/9, 4/27, 8/4, 23/8, 33/33, 18/3, 18/4, 18/8, 18/22, 18/27, 28/97, 28/104 e 28/110 não apresentaram sintomas, tiveram resultado negativo ao teste ELISA, e a maioria delas continha os genes CP e NPT II. As PTPs 1/6 e 3/46 apresentaram gene CP em homozigose e em dupla inserção. As PTPS 1/6/20, 1/6/59, 1/6/64, 1/6/90, 3/46/44, 3/46/52 e 18/27/97 apresentaram cacho de frutos bem formado, frutos piriformes com 500 g, polpa laranja e menos de 10% de carpeloidia. As PTPS 1/6/59 e 3/46/52 apresentam resistência ao PRSV, boas características agronômicas e o gene CP em homozigose.

Abstract: The objective of this work was to evaluate the resistance of transgenic papaya populations (PTPs) to Papaya ringspot virus-P (PRSV-P). 'Sunrise Solo' transgenic papaya plants were produced with the gene of the PRSV-P protein coat, and PRSV was mechanically inoculated in plants in greenhouse conditions. The presence of the CP/PRSV gene and homozygosis were evaluated by polymerase chain reaction (PCR). Selected plants and the 'Sunrise Solo' control were transplanted to the field for agronomic evaluations. The plants evaluated in greenhouse conditions showed resistance between 96.3 and 5.8%, without variation of symptoms. The PTPs 1/6, 1/7, 1/9, 1/10, 1/15, 2/38, 2/41, 2/56, 2/65, 3/27, 3/46, 3/48, 4/9, 4/27, 8/4, 8/23, 8/33, 18/3, 18/4, 18/8, 18/22, 18/27, 28/97, 28/104, and 28/110 showed no symptoms, they were ELISA negative, and most of them contained the CP and NPT II genes. PTPs 1/6 and 3/46 had the CP gene in homozygosis and in double insertion. PTPs 1/6/20, 1/6/59, 1/6/64, 1/6/90, 3/46/44, 3/46/52, and 18/27/97 had a well-formed fruit cluster, piriform fruit weighing approximately 500 grams, orange pulp, and less than 10% carpelloidy. PTPs 1/6/59 and 3/46/52 show resistance to PRSV, good agronomic characteristics, and the CP gene in homozygosis.

Resumo A mandioca de mesa pode ser comercializada congelada para facilitar o preparo e o consumo. Este trabalho teve como objetivo avaliar as características físico-químicas, o tempo de cozimento, a qualidade microbiológica e os atributos sensoriais das variedades BRS Aipim Brasil e Eucalipto, durante o armazenamento sob congelamento. As raízes foram lavadas em água, sanitizadas, cortadas em cilindros, descascadas, sanitizadas, drenadas, acondicionadas em embalagens de nylon/ polietileno de baixa densidade e armazenadas a -18 °C, sendo avaliadas a cada 30 dias, aproximadamente. A variedade Eucalipto apresentou a menor umidade (61,98%) e os maiores rendimentos de polpa (71,41%) e teor de amido (33,45%). A variedade BRS Aipim Brasil apresentou menor intensidade de cor (11,48) e maior ângulo de cor (97,45°). Os dois genótipos de mandioca não apresentaram diferenças em termos de acidez, luminosidade, sólidos solúveis, teor de açúcar total e pH. A variedade Eucalipto apresentou o menor tempo de cozimento (25 minutos) e umidade (62,92%), para os cinco tempos de armazenamento avaliados. Essa variedade também apresentou o maior teor de amido durante o armazenamento, exceto aos 31 dias. A variedade Eucalipto foi mais aceita para os atributos cor, aroma e impressão global. Em relação ao sabor e à textura, as duas variedades foram consideradas semelhantes e foram classificadas entre os termos hedônicos “gostei ligeiramente” e “gostei moderadamente”. A aceitação sensorial das raízes não foi alterada ao longo do armazenamento e as notas atribuídas foram acima de 6,0, o que representa o limite mínimo de aceitação, para todos os atributos avaliados. A mandioca congelada a -18 °C pode ser comercializada por 120 dias com segurança microbiológica, sem que ocorram alterações significativas das suas características físico-químicas e sensoriais.

Abstract Sweet cassava can be sold frozen, i.e., frozen food, to facilitate preparation and consumption. This study aimed to evaluate physical-chemical characteristics, cooking time, microbiological quality and sensory attributes regarding the varieties BRS Aipim Brasil and Eucalipto in frozen storage. The roots were washed in water, sanitized, cut into cylinders, peeled, sanitized, drained, packed in nylon/ low density polyethylene packages and stored at -18 °C, being evaluated every 30 days, approximately. The Eucalipto variety showed the lowest moisture (61.98%) and the highest pulp yield (71.41%) and starch content (33.45%). However, the BRS Aipim Brasil variety had lower color intensity (11.48) and greater color angle (97.45°) than Eucalipto. The two cassava genotypes showed no difference in terms of acidity, luminosity, soluble solids, total sugar content and pH. The Eucalipto variety showed the shortest cooking time (25 minutes) and moisture (62.92%) concerning the five storage times that were evaluated. This variety also had the highest starch content during storage, except at 31 days. The Eucalipto variety was more accepted for the color, aroma and overall impression attributes. Regarding flavor and texture, the two varieties were considered similar and were classified between the hedonic terms “like slightly” and “like moderately”. The sensory acceptance of the roots was not altered during storage and the grades attributed were above 6.0, which represents the minimum acceptance limit, for all evaluated attributes. Cassava frozen at -18 °C can be marketed for 120 days without microbiological risk, and without significant changes in its physical-chemical and sensory characteristics.

Resumo: O objetivo deste trabalho foi avaliar o potencial de obtenção de híbridos oriundos do cruzamento de cultivares de mandioca (Manihot esculenta subsp. esculenta) com as subespécies M. esculenta subsp. flabellifolia e M. esculenta subsp. peruviana. Os cruzamentos foram realizados entre plantas das cultivares BRS Jari, BRS Formosa, BRS Verdinha e BGM 2050 (Equador 72) e das duas subespécies. Por ocasião do florescimento, no período pré-antese, as flores femininas foram cobertas com saco de pano tipo voal, com posterior emasculação das flores masculinas. As flores masculinas foram coletadas e acondicionadas em frascos previamente identificados e desinfetados com álcool; algumas flores foram armazenadas em temperatura ambiente devido ao florescimento assincrônico. Os cruzamentos foram feitos entre 10 e 14 horas. Após a polinização, as flores foram cobertas novamente. As avaliações foram efetuadas desde a polinização até a deiscência dos frutos. Do total das flores polinizadas, 38% foram fertilizadas, tendo-se observado 504 frutos desenvolvidos e 816 sementes produzidas. Manihot esculenta subsp. flabellifolia como parental masculino é mais eficiente em cruzamentos com M. esculenta subsp. esculenta e pode ser indicada para cruzamentos controlados. Os cruzamentos realizados entre as cultivares de mandioca e M. esculenta subsp. flabellifolia e M. esculenta subsp. peruviana propiciam a obtenção de sementes viáveis.

Abstract: The objective of this work was to evaluate the crossability between cassava (Manihot esculenta subsp. esculenta) cultivars and the subspecies M. esculenta subsp. flabellifolia and M. esculenta subsp. peruviana. Plants from the BRS Jari, BRS Formosa, BRS Verdinha, and BGM 2050 (Equador 72) cultivars were crossed with the two subspecies. During flowering, at pre-anthesis, pistillate flowers were covered with a nylon bag and staminate flowers on the same inflorescence were emasculated. The staminate flowers were collected and placed in flasks previously labeled and sterilized with alcohol; some fresh flowers were stored at room temperature due to asynchronous flowering. The crosses were made between 10 a.m. and 2 p.m. After pollination, the flowers were covered again. Evaluations were made from the moment of pollination to the dehiscence of the fruit. Of the total flowers pollinated, 38% were fertilized, and 504 developed fruits and 816 produced seeds were observed. As a male parent, M. esculenta subsp. flabellifolia is more efficient in crosses with M. esculenta subsp. esculenta and may be recommend for controlled crosses. The crosses between the cassava cultivars and M. esculenta subsp. flabellifolia and M. esculenta subsp. peruviana produce viable seeds.

ABSTRACT Despite the widespread distribution of the Cassava common mosaic virus (CsCMV) in Brazil, little is known about the losses it causes in yield. The effect of CsCMV on different varieties was evaluated by reference to several agronomic traits. Four field trials were established in 2012/2013 and 2013/2014 using six varieties of cassava. Following mechanical inoculation with CsCMV, the presence of the virus was confirmed using the ELISA assay. The evaluated traits were plant height (PH), dry matter content (DMC), harvest index (HI), aerial part yield (APY), root yield (RoY), and starch yield (StY) in both inoculated and non-inoculated plants. Overall, the presence of the virus contributed little to the reduction in PH, HI, and DMC across the varieties, with PH being significantly reduced by 9.2 and 7.0 % in the BGM0212 and BRS Kiriris varieties, respectively. In contrast, APY, RoY, and StY were reduced by 30.2, 29.3, and 30.0 %, in the virus-infected plants respectively. While the BRS Kiriris and BRS Jari varieties suffered the highest reductions overall and were considered highly susceptible to CsCMV, none of the traits suffered reductions in the inoculated BRS Formosa plants. Although RoY and StY were reduced in inoculated plants of BRS Tapioqueira, crop yield for this variety was the highest. Thus, BRS Formosa and BRS Tapioqueira exhibited tolerance against CsCMV, which warrants further investigation.

RESUMO O conhecimento da variação fenotípica do germoplasma de mandioca (Manihot esculenta Crantz) permite estimar a variabilidade genética como suporte para seleção de genitores contrastantes. O objetivo deste trabalho foi definir grupos homogêneos de germoplasma de mandioca com base em características produtivas, resistência a doenças e qualidade de raízes utilizando o método não-hierárquico K-means. Os valores genotípicos estimados pelo BLUP (Best Linear Unbiased Predictor) foram utilizados para a análise de agrupamento. O número de grupos foi definido no início da estabilização da menor soma de quadrados dentro dos grupos. Foram obtidos 17 grupos para representar a diversidade do germoplasma, cujo número de acessos variou de 7 (Grupo 15) a 69 (Grupo 9). Em geral, os acessos pertencentes aos grupos 1; 4; 7; 12; 15 e 16, apresentaram boas características agronômicas, tais como alta produtividade de raízes frescas e de amido (> 60,7 t ha-1 e 18,6 t ha-1, respectivamente). Por outro lado, apenas o grupo 15 apresentou menor severidade de bacteriose. Os grupos obtidos apresentaram grandes diferenças entre si, conforme valores da soma de quadrados dentro dos grupos, que variavam entre 215,1 (Grupo 15) a 2338,3 (Grupo 8). O K-means permitiu a formação de grupos consistentes com base nas características agronômicas avaliadas. Portanto, o algoritmo K-means foi eficiente para a formação de grupos homogêneos com baixa variação genotípica dentro, especialmente para análises de grandes quantidades de dados, como em bancos de germoplasma de mandioca.

ABSTRACT The knowledge of the phenotypic variation of cassava (Manihot esculenta Crantz) germplasm allows the estimative of the genetic variability to support the selection of contrasting genitors. Therefore, the aim of this work was to define homogeneous groups of cassava germplasm based on yield traits, disease resistance and root quality using K-means as a non-hierarchical method. Breeding values estimated by Best Linear Unbiased Predictor (BLUP) were used for the cluster analysis. The number of groups was defined according to the stabilization of the smallest within-group sum of squares. Seventeen clusters were defined to represent the diversity of the germplasm, whose number of accessions ranged from 7 (Group 15) to 69 (Group 9). In general, accessions belonging to Groups 1, 4, 7, 12, 15 and 16 showed good agronomic traits, such as high fresh root yield and starch yield (> 60.7 t ha-1 and 18.6 t ha-1, respectively). In contrast, only Group 15 presented low bacterial blight severity. The groups obtained showed strong differences, as evidenced by the within-groups sums of squares values, which ranged from 215.1 (Group 15) to 2,338.3 (Group 8). The K-means algorithm allowed the formation of consistent groups based on yield traits, disease resistance and root quality. Therefore, the K-means algorithm was efficient in the formation of groups with low within genotypic variation, especially concerning large amounts of data, such as in cassava germplasm banks.

RESUMO: Dez cultivares de mandioca foram cultivadas no campo e avaliadas para identificar a mais adaptada aos Tabuleiros Costeiros do Nordeste do Brasil. As cultivares apresentaram diferenças nos teores de prolina e clorofila, altura, número de folhas e ramos, área de copa e produção de raízes, no entanto, não diferiram quanto às taxas fotossintéticas. As cultivares 'Tianguá' e '9783-13' apresentaram menor rendimento de raízes e 'BRS Tapioqueira' e 'Irará' maior rendimento. Poucas folhas e maior eficiência no uso da água para a assimilação de CO2 foi verificado em 'BRS Kiriris', em contraste com 'BRS Jarina' e '9783-13'. 'BRS Caipira' teve alto teor de prolina em Umbaúba e em Frei Paulo, características geralmente associadas à tolerância à seca, que contribuem para adaptação. Também é importante considerar que a cultivar 'BRS Caipira' foi a primeira a apresentar aumento no teor de clorofila após longo período de seca, o que indica recuperação mais rápida após período seco. Além disso, os resultados indicam que as cultivares mais adaptadas ao cultivo nessa área são 'Irará', 'BRS Tapioqueira', 'BRS Kiriris' e 'BRS Caipira'.

ABSTRACT: Ten cassava cultivars were grown in the field and evaluated to identify the most adapted to the Coastal Tablelands of northeast Brazil. The cultivars showed differences in proline and chlorophyll contents, plant height, number of leaves and branches, canopy area and root production, however they did not differ on photosynthetic rates. Cultivars 'Tianguá' and '9783-13' presented lower root yield, whereas 'BRS Tapioqueira' and 'Irará' had the highest root yield. Few leaves coupled with the highest water use efficiency for CO2 assimilation was found in 'BRS Kiriris' in contrast to 'BRS Jarina' and '9783-13'. 'BRS Caipira' had high proline content in both Umbaúba and Frei Paulo areas, traits usually associated to drought tolerance, that contribute to the adaptation. It is also important to consider that cultivar 'BRS Caipira' was the first to present increase in chlorophyll content after extended period of drought, that indicates a faster recovery after dry season. Furthermore, the results indicated that the most adapted cultivars for cultivation in this area are 'Irará', 'BRS Tapioqueira', 'BRS Kiriris' and 'BRS Caipira'.

Resumo: O objetivo deste trabalho foi definir procedimentos para a avaliação da tolerância de genótipos de mandioca à deterioração fisiológica pós-colheita (DFPC) e à deterioração microbiana (DM). Raízes de seis genótipos de mandioca foram avaliadas em dois experimentos, durante armazenamento em diferentes condições ambientais: alta temperatura e baixa umidade do solo; ou baixa temperatura e alta umidade do solo. As raízes foram tratadas ou não com fungicida (carbendazim) antes do armazenamento. As reações dos genótipos à DM e à DFPC foram avaliadas aos 0, 2, 5, 10, 15, 20 e 30 dias após a colheita (DAC), nas partes proximal, medial e distal das raízes. Uma escala diagramática foi proposta para avaliar sintomas não periféricos da DFPC. O tratamento com fungicida e a posição das raízes não influenciaram a expressão da DFPC; no entanto, todos os fatores apresentaram efeito significativo sobre a severidade da DM. Os genótipos diferiram quanto à tolerância à DFPC e à DM. Ambos os tipos de deterioração foram mais pronunciados durante os períodos de maior umidade e de temperaturas mais baixas. O tratamento com fungicida proporcionou maior vida de prateleira às raízes, por reduzir a severidade da DM até 10 DAC. As raízes inteiras apresentaram baixa severidade da DM e alta expressão da DFPC até 10 DAC, o que possibilitou a avaliação da DFPC sem interferência significativa dos sintomas da DM nesse período.

Abstract: The objective of this work was to define procedures to assess the tolerance of cassava genotypes to postharvest physiological deterioration (PPD) and to microbial deterioration (MD). Roots of six cassava genotypes were evaluated in two experiments, during storage under different environmental conditions: high temperature and low soil moisture; or low temperature and high soil moisture. Roots were treated or not with fungicide (carbendazim) before storage. Genotype reactions to MD and PPD were evaluated at 0, 2, 5, 10, 15, 20, and 30 days after harvest (DAH), in the proximal, medial, and distal parts of the roots. A diagrammatic scale was proposed to evaluate nonperipheral symptoms of PPD. Fungicide treatment and root position did not influence PPD expression; however, all factors had significant effect on MD severity. Genotypes differed as to their tolerance to PPD and MD. Both deterioration types were more pronounced during periods of higher humidity and lower temperatures. The fungicide treatment increased root shelf life by reducing MD severity up to 10 DAH. Whole roots showed low MD severity and high PPD expression up to 10 DAH, which enabled the assessment of PPD without significant interference of MD symptoms during this period.

The conservation, sustainable evaluation and use of cassava (Manihot esculenta Crantz) genetic resources are essential to the development of new commercial varieties. This study aimed to evaluate the quality of cassava roots and to estimate genetic variation and clustering in cassava germplasm using the Affinity Propagation algorithm (AP), which is based on the concept of "message passing" between data points. AP finds "exemplars" of each group and members of the input set representative of clusters. The genotypic data of 474 cassava accessions were evaluated over a period of two years for starch yield (StYi), root dry matter (DMC), amylose content (AML), and the level of cyanogenic compounds (CyC). The AP algorithm enabled the formation of nine diversity groups, whose number reflects the high genetic diversity of this germplasm. A high homogeneity of genetic distances was observed within all the groups, except for two groups in which there was a partial overlap caused mainly by a high variation of the CyC trait. In addition, no relationship between the genetic structure and CyC (sweet and bitter cassava) was observed. Analysis of variance of the nine clusters confirmed the presence of differences between the groups. Thus, the results of this study can be used in future breeding programs (hybridization or selection) to introduce new genetic variability into commercial cultivars to avoid problems related to low genetic variation and to improve the quality of cassava roots.

O objetivo deste trabalho foi selecionar os descritores morfoagronômicos mais informativos para o germoplasma de mandioca (Manihot esculenta), e avaliar a capacidade de diferentes métodos em selecionar os descritores. Foram caracterizados 95 acessos com uso de 51 descritores morfoagronômicos. Os dados foram submetidos à análise de correspondência múltipla (ACM), cujas informações foram utilizadas nos seguintes quatro métodos de seleção de descritores: ordem inversa do descritor para o eixo fatorial pth da ACM (Jolliffe); análise de correspondência múltipla sequencial (ACMS); média das ordens de contribuição do descritor nos três primeiros eixos fatoriais (C3PE); e método C3PE ponderado pelos pesos dos respectivos autovalores da análise completa (C3PEPond). As correlações entre a matriz de dissimilaridade com todos os descritores e os descritores mais informativos foram altas e significativas (0,75, 0,77, 0,83 e 0,84 para C3PEPond, C3PE, ACMS e Jolliffe, respectivamente). Os descritores menos informativos foram descartados, tendo-se considerado apenas aqueles comuns entre os métodos de seleção e relevantes para os interesses do melhoramento. Assim, foram selecionados 32 descritores morfoagronômicos com correlação entre as matrizes de dissimilaridade (r=0,81), em razão de sua alta capacidade para discriminar o germoplasma de mandioca e de sua habilidade de manter alguns caracteres agronômicos preliminares, úteis para a caracterização inicial do germoplasma.

The objective of this work was to select the most informative morphoagronomic descriptors for cassava (Manihot esculenta) germplasm and to evaluate the ability of different methods to select the descriptors. Ninety-five accessions were characterized using 51 morphoagronomic descriptors. Data were subjected to a multiple correspondence analysis (MCA), whose information was used in the following four methods of descriptor selection: reverse order of the descriptor for the pth factorial axis of the MCA (Jolliffe); sequential, multiple correspondence analysis (SMCA); mean of the contribution orders of the descriptor in the first three factorial axes (C3PA); and C3PA method weighted by the respective eigenvalues of the full analysis (C3PAWeig). The correlations between the dissimilarity matrix with all descriptors and the most informative descriptors were high and significant (0.75, 0.77, 0.83, and 0.84 for C3PAWeig, C3PA, SMCA, and Jolliffe, respectively). The less informative descriptors were discarded, considering those common among the selection methods and relevant for the breeding interests. Therefore, 32 morphoagronomic descriptors with correlation between the dissimilarity matrices (r=0.81) were selected, due to their high capacity to discriminate cassava germplasm and to their ability to maintain some preliminary agronomic traits, useful for the initial characterization of the germplasm.

O objetivo deste trabalho foi identificar fontes de resistência à podridão seca das raízes ocasionada por Fusarium sp. em acessos de mandioca. Inoculou-se uma suspensão (20 µL) de macroconídios de 11 isolados de Fusarium sp. em raízes de 353 acessos e sete variedades comerciais de mandioca. Dez dias após a inoculação, avaliou-se a área total colonizada pelo patógeno na polpa das raízes, por meio de análise de imagens digitais. A análise de agrupamento revelou a presença de cinco grupos quanto à resistência. As áreas lesionadas das raízes variaram de 18,28 a 1.096,07 mm² nos acessos BGM 1518 e BGM 556, respectivamente. Os genótipos BGM 1042, BGM 1552, BGM 1586, BGM 1598 e BGM 1692 apresentam as melhores características agronômicas.

The objective of this work was to identify sources of resistance to dry root rot induced by Fusarium sp. in cassava accessions. A macroconidial suspension (20 µL) of 11 Fusarium sp. isolates was inoculated in cassava roots, from 353 acessions plus seven commercial varieties. Ten days after inoculation, the total area colonized by the pathogen on the root pulp was evaluated by digital image analysis. Cluster analysis revealed the presence of five groups regarding resistance. The root lesion areas ranged from 18.28 to 1,096.07 mm² for the accessions BGM 1518 and BGM 556, respectively. The genotypes BGM 1042, BGM 1552, BGM 1586, BGM 1598, and BGM 1692 present the best agronomical traits.

Efeitos epistáticos não têm sido muito enfatizados em estudos envolvendo a estimação de parâmetros genéticos em soja. O presente trabalho teve por objetivo estimar a significância destes efeitos na produção de grãos para esta cultura utilizando-se o delineamento Triple Test Cross Modificado. Utilizaram-se 32 linhagens derivadas do cruzamento entre duas linhagens contrastantes, as quais foram cruzadas com dois testadores (L1 e L2 ). Os experimentos foram conduzidos em dois locais, em delineamentos em látice triplo 10 x 10 com nove repetições, contendo 32 linhagens (Pi ), 64 cruzamentos (32 Pi x L1 e 32 Pi x L2 ) e testemunhas. A variação entre (L1i + L2i - Pi ) revelou a presença de epistasia, bem como a ocorrência de interação epistasia x locais. Como em espécies autógamas o componente predominante de epistasia é aditiva x aditiva (tipo i), recomenda-se que a seleção para a produção de grãos seja feita em gerações mais avançadas de endogamia, para capitalizar os efeitos positivos deste tipo de epistasia.

Studies addressing the estimation of genetic parameters in soybean have not emphasized the epistatic effects. The purpose of this study was to estimate the significance of these effects on soybean grain yield, based on the Modified Triple Test Cross design. Thirty-two inbred lines derived from a cross between two contrasting lines were used, which were crossed with two testers (L1 and L2). The experiments were carried out at two locations, in 10 x 10 triple lattice designs with 9 replications, containing 32 lines (Pi ), 64 crosses (32 Pi x L1 and 32 Pi x L2 ) and controls. The variation between ( ͞L1i + ͞L2i - ͞Pi ) revealed the presence of epistasis, as well as an interaction of epistasis x environment. Since the predominant component of epistasis in autogamous species is additive x additive (i type), we suggest postponing the selection for grain yield to later generations of inbreeding in order to exploit the beneficial effects of additive x additive epistasis.