This study aimed to evaluate sulfur (S) nutrition in oil palm organs as a function of plant age. The experiment was carried out in the commercial plantations of the company Agropalma S/A (Municipality of Tailândia, Pará State, Brazil) in a dystrophic Yellow Latosol. The experiment design was completely randomized with four replications and seven treatments: plant ages (2, 3, 4, 5, 6, 7 and 8 years). The effects of treatments were evaluated in terms of concentration, accumulation, immobilization, recycling, export, and use efficiency of S in each plant organ. In the 8th year, the highest S concentration in the vegetative organs occurred in the cabbage (palm heart), while male inflorescence had higher S concentration in the 7th year in the reproductive organs. As plant age advanced, stipe and fruits were, respectively, the vegetative and reproductive organs that presented higher S accumulation. In older plants, S export occurs at higher amounts in the bunches. In oil palm, the immobilized and recycled quantity of S is higher than that exported. The use efficiency increased in the different organs of oil palm proportionally to the increase in plant age, while the S use efficiency in the rachis was 2630 times greater than that in the cabbage. In conclusion, oil palm plants change the nutritional demand as a function of age, increasing the S use efficiency and modifying the dynamics of immobilization, recycling, and export of S.

The objective of this study was to use colorimetry and visible spectroscopy to discriminate wood species obtained from the Amazon floodplain, in addition to determining the basic density and relating it to the wood colorimetric parameters. The studied material was from a community forest management area in the state of Amazonas, Brazil. For colorimetric and visible spectrum analyses, data were obtained randomly in the transverse anatomical surface. The spectral behavior of the wood samples in the visible region was evaluated. In the statistical analyses, comparisons of colorimetric parameters and visible spectra of wood from floodplain tree species were carried out. Furthermore, the basic density of the wood was determined. The best differentiation of species was achieved mainly by the hue angle. The species Pseudobombax munguba (Mart.) Dugand presented the highest median for the coordinate of the red-green axis, and the medians of the species P. munguba and Hevea spruceana (Benth.) Müll.Arg. obtained higher values of the blue-yellow axis coordinate and saturation. All species evaluated were classified as light and having low-density wood. Thus, it can be concluded that the colorimetric technique has potential to distinguish Amazon floodplain forest species.

The Brazil nut tree is considered symbolic of the Brazilian Amazon in function of its great importance, being one of the most significant extractivist products and a subsistence practice of the Indigenous people in many municipalities in Pará state. One of the main problems in different communities is related to the marketing process since it is not possible to distinguish the origin of the nuts and this causes inconvenience. The study evaluated the potential of VIS/NIR spectroscopy to identify the origin of leaves and nuts from Brazil nut trees growing in two indigenous villages, in the Xipaya Indigenous Lands, Pará state. Analysis was performed based on CIEL*a*b* parameters and using VIS (360–740 nm) and near-infrared spectra (1000–2500 nm). The samples were differentiated according to means tests, principal component analysis (PCA), and classification analysis based on k-NN. Color parameters and spectra were similar in both communities. Classification models based on k-NN produced adequate results for the distinction of villages in all evaluated situations, with accuracy of 98.54% for leaves, 89% and 90.91% for nuts with and without shell, respectively. Near infrared can be applied in forests as a technique for previous provenance identification and contribute to the subsistence and sustainable practice of extraction.