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 objetivo deste trabalho foi desenvolver uma escala para avaliar a severidade da deterioração fisiológica pós-colheita (DFPC) da mandioca, e validar esta escala quanto a estimativas de acurácia e reprodutibilidade. Uma escala diagramática (0 a 100%) referente à área lesionada das raízes foi avaliada de acordo com sua precisão, acurácia e reprodutibilidade. Sete avaliadores (quatro experientes e três inexperientes) quantificaram a severidade da DFPC, com ou sem o uso da escala, tendo-se considerado 150 raízes com diferentes níveis de DFPC. Sem e com o uso da escala, respectivamente, os avaliadores inexperientes obtiveram coeficiente de determinação (R2) de 0,76 a 0,86 e de 0,87 a 0,92, e os avaliadores experientes obtiveram R2 de 0,90 a 0,96 e de 0,96 a 0,97. Os valores do intercepto (a), obtidos tanto pelos avaliadores experientes como pelos inexperientes, sem uso da escala, foram significativos, enquanto, após o uso da escala, apenas dois avaliadores obtiveram valores que não foram significativamente diferentes de um. A reprodutibilidade das avaliações entre os avaliadores variou de 0,61 a 0,91, para os inexperientes, e de 0,83 a 0,95, para os experientes. A escala diagramática proposta foi considerada adequada para estimar a severidade da DFPC em raízes de mandioca e poderá ser utilizada para identificar fontes de tolerância à deterioração pós-colheita.

Abstract:The objective of this work was to develop a scale to assess the severity of postharvest physiological deterioration (PPD) of cassava roots, and to validate this scale for accuracy and reproducibility estimates. A diagrammatic scale (0 to 100%) for the damaged roots was analyzed according to precision, accuracy, and reproducibility. Seven evaluators (four with experience and three without it) quantified the PPD severity, with or without the scale, considering 150 roots with different levels of PPD. Without and with the use of the scale, respectively, the inexperienced evaluators obtained coefficients of determination (R2) from 0.76 to 0.86 and 0.87 to 0.92, and the experienced evaluators obtained R2 from 0.90 to 0.96 and 0.96 to 0.97. The values of the intercept (a) obtained by both the experienced and inexperienced evaluators who did not use the scale were all significant, while after using the scale, only two evaluators got values that were not significantly different from one. Evaluation reproducibility between the evaluators ranged from 0.61 to 0.91 for the inexperienced ones and from 0.83 to 0.95 for the experienced ones. The proposed diagrammatic scale was considered appropriate to estimate the severity of PPD in cassava roots, and can be used to identify sources of tolerance to postharvest deterioration.

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.

Corynespora cassiicola, um patógeno com ampla gama de hospedeiros, tem causado graves danos nos viveiros de mamoeiro na Bahia. Avaliou-se, em ambiente misto de cobertura e a pleno sol, a incidência natural de C. cassiicola em 49 acessos de mamoeiro em experimento conduzido em blocos casualizados com quatro repetições, 49 tratamentos e variável número de plantas/tratamento. O número de plantas com sintomas e mortas por C. cassiicola foi avaliado aos 27 e 32 dias após a semeadura. A análise de Cluster (p< 0,05) classificou os acessos em 5 grupos pelo número médio de plântulas infectadas e mortas. Os acessos com menor porcentagem de plântulas infectadas foram: Sunrise solo 72/12, Sunrise solo, Golden comercial, Grampola, Kapoho solo (polpa vermelha), Mamão roxo e Santa Helena (50A PLT - 09, 14A PLT - 05, 12A PLT- 06, 12A PLT - 07, 02A PLT -01). Nova sintomatologia causada pelo patógeno é descrita.

Corynespora cassiicola, a pathogen showing a wide range of hosts, has caused severe damage to papaya nurseries in Bahia. The present study evaluated, under mixed environment of coverage and full sun, the natural incidence of C. cassiicola in 49 papaya accessions as randomized blocks with four replicates, 49 treatments and variable number of plants per treatment. The number of symptomatic or dead plants due to C. cassiicola was evaluated at 27 and 32 days after sowing. Cluster Analysis (p< 0.05) classified the accessions into 5 groups according to the average number of infected or dead seedlings. Accessions showing the smallest percentage of infected seedlings were: Sunrise solo 72/12, Sunrise solo, Golden comercial, Grampola, Kapoho solo (red pulp), Mamão roxo and Santa Helena (50A PLT - 09, 14A PLT - 05, 12A PLT- 06, 12A PLT - 07, 02A PLT - 01). A new symptomatology caused by this pathogen is described.

Em função da importância da casca do fruto como principal resíduo da cacauicultura e as possibilidades de seu uso, este trabalho teve como objetivos realizar análise de nutrientes do extrato orgânico obtido por lavagem do composto de casca e avaliar seu efeito como fertilizante potássico no solo e no crescimento de mudas de cacaueiro. O ensaio foi realizado em casa de vegetação, com aplicação de doses de extrato via solo, cultivo em tubetes e mudas seminais de cacaueiro. O delineamento experimental foi em blocos casualizados, com três repetições, e a unidade experimental formada por nove plantas crescidas individualmente em tubetes. Os tratamentos foram 5 doses de K: zero; 125; 250; 500 e 1.000 mg de K dm-3 de solo. Após 120 dias da aplicação do extrato no solo, verificou-se que o pH, a saturação de bases e os teores disponíveis de Ca, Mg, K, Zn e Mn aumentaram, e o teor de Al e Fe diminuíram. Os resultados também evidenciaram que a dose de 1.000 mg K dm-3 de solo desequilibrou as relações K/Mg e K/Ca nas folhas com redução no crescimento das mudas. Mudas de cacaueiro apresentaram crescimento significativo em função de doses de K e, considerando a facilidade de produzir e aplicar o extrato da casca do fruto do cacaueiro, é possível usá-lo como fonte de K na produção de mudas de cacaueiro.

Considering the importance of the bark of cocoa as the main crop residue in cocoa farms, the objective of this study was to make analysis of nutrients from the organic extract obtained by washing the compost of the bark and to evaluate the effect of this extract as potassium fertilizer in soils and growth of cocoa seedlings. The experiment was conducted in a greenhouse with application of extract in the soil, growing in plastic tubes and seedlings of cocoa. The experimental design was in randomized blocks with three replications and experimental units consisting of nine plants grown individually in plastic tubes. The treatments were five K levels: zero, 125, 250, 500 and 1000 mg K dm-3 of soil. After 120 days of the extract application in the soil, it was found that pH, base saturation and Ca, Mg, K, Zn and Mn available increased while the content of Al and Fe were reduced. The results also showed that the dose 1000 mg K dm-3 of soil unbalanced the ratio K/Mg and K/Ca in leaves with reduced growth of seedlings. The application of bark extract increased significantly the available of K in the soil and concentration in plants. Cocoa seedlings showed growth in responses to different levels of K and, considering the easily of manufacture and applying the extract of the cacao bark, there is possible of the use as a source of K in the production of cocoa seedlings.