Anatomical and histochemical aspects of the peach palm (Bactris gasipaes Kunth) seed

Bactris gasipaes Kunth (peach palm) is a palm tree (Arecaceae) widely used by Amazon people, whose seeds have dormancy of unknown cause, which result in difficulties on producing uniform seedlings. This study aimed at identifying anatomical and histochemical aspects of peach palm seeds that may have influence on germination. Histological sections were performed with seed material embedded into hystoresin, which were then stained with toluidine blue and assessed under optical microscope to verify structural characteristics. Histological sections were manually performed to identify primary and secondary metabolites; and histochemical test were performed for fatty acids, alkaloids, starch, phenolic compounds, lignin, neutral and acidic lipids, pectins, polysaccharides, proteins, tannins, and terpenoids. Tegument is thin and contains two layers. The external layer is thicker and has vascular bundles; and the internal layer is thinner containing irregular cells replete of phenolic compounds. Endosperm is whitish in color, with cells with shapes that vary from oblong or ellipsoidal until oval; containing lipids, proteins, pectins, and polysaccharides. Embryo is relatively small as related to seed size, conical and vascularized at distal portion. On longitudinal sections, plumule appears in proximal region as three foliar primordia. At seedling protrusion region the cells contain acidic lipids, proteins, and neutral polysaccharides

Nutrientes foliares de espécies arbóreas de três estádios sucessionais de floresta ombrófila densa no sul do Brasil Leaf nutrient content of tree species from three successional stages of tropical rain forest in south Brazil

As concentrações de macro e micronutrientes foliares de espécies arbóreas foram avaliadas em três estádios sucessionais (inicial, intermediário e avançado) de uma floresta ombrófila densa das terras baixas, no litoral do Estado do Paraná, crescendo sobre solo arenoso e oligotrófico. Dentre as espécies arbóreas mais importantes de cada estádio sucessional (quatro iniciais; oito intermediárias; 11 avançadas), coletou-se folhas maduras de cinco diferentes indivíduos de cada estádio sucessional para a análise química dos seguintes elementos: N, P, K, Ca, Mg, C, Zn, Fe, Cu e Mn. As espécies do estádio inicial possuem as menores concentrações médias foliares de N, P, K, Zn, Fe e a maior concentração de Mg e estas concentrações são estatisticamente diferentes (p <0,05), quando comparadas com os valores médios dos demais estádios. Nos estádios intermediário e avançado, as concentrações médias de N, Ca e Mg, assim como os micronutrientes estão dentro dos valores esperados para florestas tropicais. As concentrações médias de K, nos estádios inicial e intermediário, e as concentrações médias de P, em todos os estádios, encontram-se abaixo dos valores reportados para as florestas tropicais. A relação C/N é alta (>25:1), apesar da tendência de diminuir à medida que avança a sucessão. O aumento da concentração da maioria dos nutrientes foliares analisados ao longo do gradiente sucessional está associado, possivelmente, com o incremento do acúmulo da serapilheira sobre o solo, o que proporciona ciclagem de nutrientes mais intensa e maiores concentrações de nutrientes no solo.<br>We investigated the leaf nutrient content of trees species from three distinct successional stages (early, intermediate, late) of a lowland rain forest located near the coast of Paraná State, Brazil. This forest grows on sandy soil with low nutrient content. We collected mature leaves from five different individuals of each sucessional stages of the most important tree species of each successional stage (four of the early; eight of the intermediate and 11 of the late stages) for chemical analysis of following elements: N, P, K, Ca, Mg, C, Zn, Fe, Cu e Mn. The species from early sucessional stage have lower contents of N, P, K, Zn, Fe, and higher contents of Mg. These concentrations are statistically different (p <0,05) when compared to mean values of the other stages. For the intermediate and late successional stages, the average nutrient concentrations of N, Ca, Mg and micronutrients are within the range of values expected for tropical forests. Foliar K concentration, from early and intermediate successional stages, and foliar P concentration, for all successional stages, are below the reported range of values for tropical forests. The C/N ratio is high (>25:1), despite of the tendency to decrease as succession advances. The increment of concentration of the most studied foliar nutrients along the successional gradient is probably related to the accumulation of litter above the soil that provides a more adequate environment for efficient nutrient cycling and higher nutrient concentration in the soil