Genetic variability of cocoa from the amazon basin: implications for genetic conservation

The cocoa and chocolate production chain involves US$60 billion annually and three million farmers around the world, in an area exceeding nine million hectares. The use of wild germplasm will enable to generate new disease- and pest-resistant cultivars and ability to adapt to changing environments. Here we evaluated 145 cocoa accessions, originated from nine Amazonian basins, based on eight fruit traits. Univariate anova showed significant differences (p<0.05) for all traits. For seven traits, the variance component within basins was higher (81.5%, on average). Therefore, it is recommended that the collection of wild accessions prioritize a larger number of plants from a few populations of the most divergent basins. The multivariate analyses revealed a greater divergence between the Ji-Paraná-RO and Solimões/Amazonas-PA basins (27.69) and a greater similarity between Alien clones-PER and Solimões/Amazonas-AM (0.66) in relation to their populations. They also revealed that the accessions differentiation occurred according to the river basin system. These results allowed elucidate the genetic structure and distribution of cacao populations. In addition, strengthen the importance of collecting and conserving germplasm to preserve genetic resources.

Inhibition of tuber sprouting in potato cultivars Asterix and Challenger by 1 4-dimethylnaphthalene / Inibição da brotação dos tubérculos das cultivares de batata Asterix e Challenger pelo 1 4-dimetilnaftaleno

The aim of this study was to verify the efficiency of 1,4-dimethylnapthalene in suppressing sprouting and the consequent maintenance of the quality of potato tubers of Asterix and Challenger cultivars, at different temperatures and storage regimes. Six treatments were tested, with and without 1.4-DNM, at temperatures of 8 ° C and 20 ° C. Assessments were made at 0, 45, 90, 135 and 180 days after application. The parameters evaluated were: number of sprouts, levels of total soluble sugars, levels of reducing and non-reducing sugars and coloration of potato strips after frying. The effects of 1.4-DMN on the quality control of potatoes resulted in sprout control and lower levels of total soluble sugars and reducing sugars, especially in the Challenger cultivar and at a temperature of 20 ºC.

Objetivou-se com este estudo verificar a eficiência do 1,4-dimetilnaftaleno na supressão da brotação e a consequente manutenção da qualidade de tubérculos de batata das cultivares Asterix e Challenger, em diferentes temperaturas e tempos de armazenamento. Foram testados seis tratamentos, com e sem 1,4-DNM, nas temperaturas de 8 °C e 20 °C. As avaliações foram feitas aos 0, 45, 90, 135 e 180 dias após a aplicação. Os parâmetros avaliados foram: número de brotos, teores de açúcares solúveis totais, teores de açúcares redutores, e não redutores, e coloração dos palitos de batata após a fritura. Os efeitos do 1,4-DMN no controle da qualidade das batatas resultaram no controle da brotação e em menores teores de açúcares solúveis totais e de açúcares redutores, sobretudo na cultivar Challenger e à temperatura de 20 ºC.

Genetic evaluation and selection of cocoa tree clones / Avaliação genética e seleção de clones de cacaueiro

The cultivation of cocoa is of great socio-economic importance worldwide. Cocoa beans are the essential raw material for chocolate production. The variability of cacao studied presents only a small fraction of the existing genetic diversity, mainly in the Amazon region. Furthermore, just a small part of this variability has been exploited in cocoa breeding. Thus, the present study processed the genetic evaluation and selection of cocoa clones, based on morpho-agronomical traits. For this, we evaluated 145 clones, during 37 harvests from, four consecutive years. The following traits were evaluated: total number of fruits collected (TNFC), total number of healthy fruits (TNHF), weight of wet seeds from healthy fruits (WWSHF), average weight of wet seeds per healthy fruit (AWWSHF), weight of dry seeds from healthy fruit (WDSHF), average weight of dry seeds per healthy fruit (AWDSHF), percentage of fruits with witches' broom disease (PFWB), percentage of fruits with borer (PFBR), percentage of fruits with germinated seeds (PFGS), number of branches with witches' broom disease (NBWB), and number of inflorescence with witches' broom disease (NIWB). Significant differences (P < 0.05) among the clones were observed for all traits, which reveal an expressive variability and possibility of gains with selection. The highest significant correlations (P < 0.05) occurred between traits TNFC and TNHF (0.94), TNHF and AWWSHF (0.86), and TNHF and AWDSHF (0.86). Based on the selection index, the clones POUND 12 and CAB 12, 228, 253, 257, 258, and 422 were the most suitable for selection.

O cultivo do cacau tem grande importância socioeconômica mundial. Os amêndoas de cacau são a matéria-prima essencial para a produção de chocolate. A variabilidade do cacaueiro avaliada representa apenas uma pequena fração da diversidade genética existente, principalmente na região amazônica. Além disso, apenas uma pequena parte dessa variabilidade foi explorada no melhoramento de cacau. Dessa forma, o presente estudo teve como objetivo realizar a avaliação genética e seleção de clones de cacau, com base em características morfo-agronômicas. Para isso, foram avaliados 145 clones, durante 37 colheitas, em quatro anos consecutivos. As seguintes características de frutos e sementes foram avaliadas: número total de frutos colhidos (NTFC), número total de frutos sadios (NTFS), peso de sementes úmidas dos frutos sadios (PSUFS), peso médio de sementes úmidas dos frutos sadios (PMSUFS), peso de sementes secas dos frutos sadios (PSSFS), peso médio de sementes secas dos frutos sadios (PMSSFS), porcentagem de frutos com vassoura-de-bruxa (PFVB), porcentagem de frutos com broca (PFBR), porcentagem de frutos com sementes germinadas (PFSG), número de ramos com vassoura-de-bruxa (NRVB) e número de almofadas florais com vassoura-de-bruxa (NAFVB). Diferenças significativas (P < 0,05) entre os clones foram observadas para todas as características, o que revela uma expressiva variabilidade e possibilidade de ganhos com a seleção. As maiores correlações significativas (P < 0,05) ocorreram entre os caracteres NTFC e NTFS (0,94), NTFS e PMSUFS (0,86) e, NTFS e PMSSFS (0,86). Com base no índice de seleção, os clones POUND 12 e CAB 12, 228, 253, 257, 258 e 422 foram considerados os mais adequados para a seleção.