ABSTRACT Leaf litter decomposition and the release of nutrients from macauba palm leaves play a major role in nutrient return to the soil in a conservation environment. This study evaluated macauba palm leaf decomposition, macronutrient contents and biochemical composition under contrasting water conditions in the Brazilian Cerrado. Macauba leaves were collected from plants in two different environments (low and high water table conditions), placed in litter bags and evaluated according to their decomposition, macronutrients, lignin, cellulose and hemicellulose for 420 days. In addition, green and dry leaves were collected for macronutrient analyses. Litter decomposition ranged between 49 % and 59 % up to 180 days. The half-life of litter ranged from 141 to 198 days. The leaf litter decomposition of macauba was practically stable during the dry season, whereas at the beginning of the rainy season, decomposition resumed. Nitrogen, P and S were higher in the green leaves, whereas the Ca levels were higher in the dry leaves. In addition, the K levels were twofold higher in the green leaves than in the dry leaves. Lignin release from macauba residues was slower than cellulose and hemicellulose. The decomposition rates of hemicellulose were higher initially due to its high solubility, although it gradually decreased with the decomposition process. Lignin decomposition was also higher at the beginning of the process but stabilized during the drought period. The study indicates that the decomposition process and nutrient cycling of macauba are influenced by its biochemical composition. environment Cerrado low conditions, , conditions) macronutrients lignin 42 days addition analyses 4 5 18 halflife half life 14 19 season resumed Nitrogen solubility period 1

O objetivo deste estudo foi caracterizar, pela primeira vez, os polifenois totais e a atividade antioxidante por DPPH (2- difenil-1- picryhydrazyl radical) em acessos cultivados de Phaseolus lunatus L., provenientes de uma coleção de germoplasma mantida pela Embrapa, no Brasil, e detectar mudanças nos teores de polifenóis totais, flavonoides e taninos condensados, após a regeneração dos acessos em casa de vegetação. Os resultados mostraram a diversidade da coleção de fava para compostos fenólicos, que foram fortemente correlacionados com a atividade antioxidante. Os acessos de fava com os teores mais elevados de polifenóis e de atividade antioxidante foram aqueles com sementes coloridas. A conservação das sementes de P. lunatus na câmara fria da coleção de germoplasma não afetou, necessariamente, os polifenois, sendo que as variações após a regeneração das sementes parecem resultar principalmente de fatores bióticos e abióticos, incluindo não apenas cultivar, mas também condições ambientais. Este estudo sugeriu que os polifenóis da fava apresentam atividade antioxidante, com possíveis efeitos benéficos para a saúde humana. Esperamos que o potencial deste apetitoso legume também possa ser aplicado como alimento funcional e/ou como um novo ingrediente na gastronomia.

The objective of this study was to characterize for the first time polyphenols and DPPH (2-diphenyl-1-picryhydrazyl radical) antioxidant activity in commonly cultivated accessions of Phaseolus lunatus from an ex situ germplasm collection maintained by Embrapa, in Brazil. Furthermore, the study aimed to detect changes in total polyphenols, total flavonoids and condensed tannin for the same accessions after regeneration in a greenhouse. The results showed the diversity of the lima bean collection for phenolic compounds, which were strongly correlated with antioxidant activity. Lima beans accessions with the highest polyphenols and antioxidant activity were those with colored seeds. Conservation through cold storage of P. lunatus seeds in a cold chamber in the germplasm collection did not necessarily affect phenolic compounds. Variations observed in values after regeneration seeds may be mainly results of biotic and abiotic factors, including not only cultivar, but also environmental conditions. This study suggests that polyphenols in the lima beans present antioxidant activity, with possible beneficial effects for human health. It was expected that the potential of this tasty legume can be also used as a functional food crop and/or as a new ingredient in gastronomy.