Abstract The prickly pear is a cactaceae that have chemical compounds that act as natural antioxidants. In addition, the prickly pear is a plant widely used in semiarid region as it’s considered very important forage for animal feed, especially in the dry season. The objectives of this research were to characterize the main classes of phytochemicals, determine the phenols content, flavonoids and anthocyanins and evaluate the antioxidant activity of the prickly pear cultivars Opuntia and Nopalea grown in the semiarid region of Pernambuco in two collection periods (dry and rainy). In the work crude ethanol extracts from cladodes of cultivars (IPA-20, Elephant Ear Mexican, F-08, V-19, Small palm, F-21 and IPA-Sertânia) were used. As for the class of phytochemical compounds from ethanol extract only the flavonoids and steroids were detected in all prickly pear cultivars, in both periods analyzed. The content of phenolic compounds ranges from 1.24 to 5.41 mg GAE g-1 DM, flavonoids 0.90 to 3.43 mg QE g-1 DM, anthocyanins from 0.05 to 0.34 µg QE 100 g-1 DM and antioxidant activity 39.59 to 217.17 µM TEAC g-1 DM. The occurrence of chemical variability and antioxidant activity were observed, both among the botanical cultivars studied and among the collection periods.

Um dos efeitos da salinidade causado por excesso de Na+ nos solos é a redução dos níveis de K+ nos tecidos vegetais. O trabalho objetivou caracterizar as vias de absorção de K+ de alta e baixa afinidade em raízes de cajueiro na ausência e presença de concentrações de Na+. Os estudos de cinética de absorção de K+ na ausência e presença de NaCl foram realizados com raízes destacadas de plântulas de cajueiro cultivadas sob privação de K+. O excesso de Na+ no meio externo causou redução da absorção de K+ pelos sistemas de alta e de baixa afinidade. A redução da absorção de K+, causada pelo excesso de Na+ no meio, nas raízes de cajueiro ocorre por mecanismo competitivo. Esse tipo de competição foi evidenciado pelo aumento dos valores de Km para a absorção de K+ induzido pelo Na+ externo, sem alterar os valores de Vmáx. Os resultados mostram que a salinidade pode comprometer a aquisição e a utilização de K+ em plantas de cajueiro.

One effect of the salinity caused by an excess of Na+ in soils, is the reduction in levels of K+ in plant tissue. The study aimed to characterize the process of high and low-affinity absorption of K+ in cashew roots, in both the absence and presence of concentrations of Na+. Studies of the kinetics of K+ absorption in the absence and presence of NaCl were carried out using detached roots from cashew seedlings grown under K+ deprivation. The excess of Na+ in the external environment caused a reduction in K+ absorption by both the high and low-affinity systems. The reduction in the absorption of K+ in the roots of the cashew tree, caused by the excess Na+ in the environment, happens through competitive means. This type of competition was evidenced by the increase in Km values for the K+ absorption induced by the external Na+, without changing the values of Vmax. The results show that salinity may affect the acquisition and use of K+ in cashew plants.

O objetivo deste trabalho foi avaliar a resistência à salinidade de genótipos de cajueiro dos grupos anão e gigante, em mudas em fase de enxertia, com o uso de indicadores fisiológicos. A germinação e o crescimento inicial de plântulas de dez genótipos de porta-enxertos foram avaliados sob duas condições de salinidade: irrigação do substrato com água destilada ou com solução de NaCl 50 mmol L-1, até o estádio de oito folhas maduras (28 dias após o plantio). As mudas foram irrigadas com solução nutritiva de Hoagland & Arnon por mais dez dias. Os indicadores fisiológicos de resistência - concentrações de Na+ e K+ e relação K+/Na+, em folhas e raízes - não diferiram entre os genótipos, na ausência ou na presença de salinidade. Os indicadores e as concentrações de prolina não se correlacionaram com a massa acumulada em raízes e folhas. Sob salinidade, os genótipos do grupo anão apresentaram maior massa radicular em comparação aos do grupo gigante, que tiveram maior alocação de massa em folhas. Houve baixa variabilidade genética dentro de cada grupo. Quanto ao crescimento de raízes e folhas, houve variabilidade entre os grupos, nas duas condições de salinidade.

The objective of this work was to evaluate the resistance to salinity of cashew genotypes from dwarf and giant groups, with seedlings in pregrafting phase, using physiological indicators. Germination and seedling initial growth of ten rootstock genotypes were evaluated under two salinity conditions: substrate irrigated with distilled water or with 50-mmol L-1 NaCl solution, until the eight mature leaves stage (28 days after sowing). The seedlings were irrigated with Hoagland & Arnon nutrient solution, for ten more days. Physiological indicators of resistance - Na+ and K+ contents and K+/Na+ relation, in leaves and roots - did not differ between genotypes, in the absence or presence of salinity. The indicators and prolin contents were not correlated to the accumulated mass in roots and leaves. Under salinity conditions, the genotypes from the dwarf group showed higher root mass in comparison to those from the giant group, which had greater mass allocation in leaves. There was low genetic variability within each group. Regarding root and leaf growth, there was variability between groups, in both salinity conditions.