In ecological setting, sodium (Na+) can be beneficial or toxic, depending on plant species and the Na+ level in the soil. While its effects are more frequently studied at high saline levels, Na+ has also been shown to be of potential benefit to some species at lower levels of supply, especially in C4 species. Here, clonal plants of the major tropical C3 crop Theobroma cacao (cacao) were grown in soil where potassium (K+) was partially replaced (at six levels, up to 50% replacement) by Na+, at two concentrations (2.5 and 4.0 mmolc dm−3). At both concentrations, net photosynthesis per unit leaf area (A) increased more than twofold with increasing substitution of K+ by Na+. Concomitantly, instantaneous (A/E) and intrinsic (A/gs) water‐use efficiency (WUE) more than doubled. Stomatal conductance (gs) and transpiration rate (E) exhibited a decline at 2.5 mmol dm−3, but remained unchanged at 4 mmol dm−3. Leaf nitrogen content was not impacted by Na+ supplementation, whereas sulfur (S), calcium (Ca2+), magnesium (Mg2+) and zinc (Zn2+) contents were maximized at 2.5 mmol dm−3 and intermediate (30–40%) replacement levels. Leaf K+ did not decline significantly. In contrast, leaf Na+ content increased steadily. The resultant elevated Na+/K+ ratios in tissue correlated with increased, not decreased, plant performance. The results show that Na+ can partially replace K+ in the nutrition of clonal cacao, with significant beneficial effects on photosynthesis, WUE and mineral nutrition in this major perennial C3 crop.

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Cadmium (Cd) is a highly toxic metal for plants, even at low concentrations in the soil. The annual production of world cocoa beans is approximately 4 million tons. Most of these fermented and dried beans are used in the manufacture of chocolate. Recent work has shown that the concentration of Cd in these beans has exceeded the critical level (0.6mgkg DM). The objective of this study was to evaluate the toxicity of Cd in young plants of CCN 51 cacao genotype grown in soil with different concentrations of Cd (0, 0.05 and 0.1gkg soil) through photosynthetic, antioxidative, molecular and ultrastructural changes. The increase of Cd concentration in the soil altered mineral nutrient absorption by competition or synergism, changed photosynthetic activity caused by reduction in chloroplastidic pigment content and damage to the photosynthetic machinery evidenced by the Fv/Fm ratio and expression of the psbA gene and increased GPX activity in the root and SOD in leaves. Additionally, ultrastructural alterations in roots and leaves were also evidenced with the increase of the concentration of Cd in the soil, whose toxicity caused rupture of biomembranes in root and leaf cells, reduction of the number of starch grains in foliar cells, increase of plastoglobules in chloroplasts and presence of multivesiculated bodies in root cells. It was concluded, therefore, that soil Cd toxicity caused damage to the photosynthetic machinery, antioxidative metabolism, gene expression and irreversible damage to root cells ultrastructure of CCN 51 cocoa plants, whose damage intensity depended on the exposure time to the metal.

RESUMO:A espécie Phaseolus lunatus L., conhecida popularmente como feijão-fava constitui uma das alternativas de renda e alimentação para a população da região Nordeste do Brasil. Um dos problemas enfrentados são as doenças que provocam grandes perdas na produção de sementes. O presente trabalho objetivou avaliar a eficiência dos óleos essenciais de copaíba, cravo-da-índia e manjericão na redução da incidência de fungos associados às sementes de feijão-fava, e sua interferência na qualidade fisiológica. Os tratamentos foram constituídos por óleos essenciais de copaíba, cravo-da-índia e manjericão nas concentrações de 0; 1; 1,5 e 2 mL. L -1 e fungicida (Captan ® ). Foram utilizadas 200 sementes por tratamento. Para análise da qualidade sanitária das sementes foi adotado o método de incubação em placas de Petri contendo dupla camada de papel-filtro umedecida com ADE, sob temperatura de 20 ±2 ºC, por 7 dias. A qualidade fisiológica das sementes foi determinada com base nos testes de germinação, emergência e vigor das sementes. Para o teste germinação foi empregado método de rolo de papel germitest e na emergência osemeio foi realizado em bandejas plásticas contendo areia lavada esterilizada, em condição de casa de vegetação, e após 9 dias da instalação foi determinado o vigor com base nos resultados de índice de velocidade de germinação e emergência; comprimento da parte aérea, raiz primária e plântula; e teor de massa seca da partes aérea, raízes e plântulas de feijão-fava. O delineamento experimental foi interiamente casualizados, em esquama de fatorial simples (3x4)+1 (óleos essenciais x concentrações + fungicida), com quatro repetições de 50 sementes. Os óleos essenciais de copaíba e manjericão reduziram consideravelmente o percentual de incidência dos fungos associados as sementes de feijão-fava. O óleo essencial de cravo-da-índia na concetração de 2 mL. L -1 , reduziu a qualidade fisiológica das sementes de feijão-fava. Palavras-chave:Copaifera langsdorffii, Caryophyllus aromaticus, Ocimum basilicum, Sanidade, Qualidade fisiológica. ABSTRACT: Efficiency of essential oils in the sanitary and physiological quality of lima bean seeds (Phaseolus lunatus L.).The Phaseolus lunatus L. species, popularly known as lima bean, is one of the alternative sources of income and food for the population of Northeast Brazil. One of the problems is the diseases that cause great losses in seed production. This study evaluated the effectiveness of essential oils of copaiba, clove, and basil in reducing the incidence of fungi associated with lima bean seeds, as well as the effect on their physiological quality. The treatments consisted of essential oils of copaiba, clove, and basil at concentrations of 0; 1; 1.5; and 2 mL. L-1 and fungicide (Captan®). A total of 200 seeds were used per treatment. To analyze the sanitary quality of the seeds, the method used was incubation in petri dishes containing a double layer of filter paper moistened with distilled sterilized water at a temperature of 20 ± 2°C, for seven days. The physiologic...