ABSTRACT Background: The aim of this research was to investigate the efficiency of methods to overcome primary dormancy and biochemical processes associated with germination of Erythrina falcata Benth seeds. Seeds were submitted to dormancy overcoming treatments and the water uptake pattern was analysed. We then evaluated the activity of the antioxidant enzymes SOD, CAT, and APX, and quantified lipid peroxidation levels, hydrogen peroxide content and total protein content. The experiments were performed in a completely randomized design and the statistical analysis used was Scott-Knott test at 5% probability. Results: Mechanical scarification with sandpaper leads to approximately 94% of germination in E. falcata, while control non-scarified seeds show only approximately 37% of germination. Treatments with hot water led to high mortality in E. falcata seeds. Rapid water absorption was observed in the first 18 hours of imbition when the seeds were scarified with sandpaper, and radicle emergence was observed after 36 hours. During imbibition there was an increase of antioxidant enzyme activity and a decrease in lipid peroxidation and H2O2 production, suggesting an efficient mechanism for regulating imbibition damage. A decrease in the total protein content was observed during germination of E. falcata seeds. Conclusions: Mechanical scarification is an efficient method for breaking dormancy of E. falcata seeds. During germination of E. falcata seeds there is a reduction in the production of H2O2 and lipid peroxidation, and an increase in the activity of antioxidant enzymes. The total protein content decreased along the germination time.

ABSTRACT The non-structural carbon reserves in the various organs of trees are associated with their growth and the mechanism of resilience when exposed to environmental stresses, especially the water deficit. The goal of this study was to develop multivariate models to estimate the amount of non-structural carbohydrates (starch, sucrose, reducing sugars, total sugars and total non-structural carbohydrates) based on near infrared (NIR) spectra measured in solid wood and material reduced to powder. Partial least squares regression was used to associate the amount of non-structural carbohydrates (NSC) obtained by conventional laboratory analysis with NIR spectral signatures. The best predictive models were obtained from the wood reduced to powder. Validity for the NSC prediction in an external set of data presented the following statistics: reducing sugars with R²=0.90 and root mean square error (RMSE) of 2.54% dry matter, total sugars (R²=0.88, RMSE=2.76%), total NSC (R²=0.90, RMSE=2.58%), sucrose (R²=0.82, RMSE=0.06%) and starch (R²=0.80, RMSE=1.03%). The ability of models to estimate the NSC concentration in the growth rings and under divergent environmental conditions demonstrates the potential of the NIR tool to study the physiological responses of plants to different environmental stresses.

ABSTRACT. Agricultural species are subjected to a variety of biotic and abiotic stresses, which are the main limitations to crop production. In this context, contamination by trace elements is characterized as an abiotic stress that represents an environmental problem. Due to the physical and chemical similarities between cadmium and zinc, these elements may interact in the environment and may cause antagonistic or synergistic effects. In this way, physiological mechanisms to exclude, detoxify or compartmentalize trace elements that are in excess are crucial for plant survival when exposed to high concentrations of these elements. In this way, the aim of this study was to understand the physiological responses of Phaseolus vulgaris plants subjected to increasing doses of Cd and Zn for 21 days in different soil, Cambisol and Latosol. The activity of antioxidant enzymes, such as SOD, CAT, and APX; hydrogen peroxide content; lipid peroxidation; chlorophyll index; photosynthetic rate; stomatal conductance; and transpiration were analysed. The data obtained showed a specific behaviour of Phaseolus vulgaris plants in each soil analysed. Moreover, it was observed that interactions between both elements resulted in a synergistic effect, negatively affecting all of the parameters analysed.

RESUMO. O objetivo desse trabalho foi avaliar a relação entre a toxicidade de manganês e a tolerância ao alagamento em plantas de Zea mays L. cv. Saracura do 18º ciclo de seleção. Plantas de milho foram transferidas para recipientes plástico contendo soluções com diferentes concentrações de manganês. Folhas e raízes foram coletadas antes dos tratamentos, 7, 14 e 21 após a imposição dos tratamentos para as análises de conteúdo de clorofilas e carotenoides, produção de biomassa e metabolismo antioxidante. O Mn foi fortemente translocado das raízes para as folhas desencadeando uma considerável redução no conteúdo foliar de clorofila. O excesso de Mn desencadeou uma aumento na produção de espécies reativas de oxigênio, o que foi acompanhado por uma elevação na atividade das enzimas do metabolismo antioxidante e da peroxidação lipídica. Zea mays L. cv. Saracura demonstrou ser eficiente no sequestro de uma grande quantidade de Mn nas folhas, com um significativo impacto no metabolismo, no entanto sem o aparecimento de sintomas visuais e sem uma grande redução no seu crescimento.

ABSTRACT. The objective of this study was to evaluate the relationship between excess manganese and waterlogging tolerance in 18th selection cycle Zea mays L. cv. Saracura plants. Maize plants were transferred to plastic receptacles containing solutions with different concentrations of manganese. Leaves and roots were evaluated at the beginning of treatment and after 7, 14, and 21 days for chlorophyll content, biomass production and antioxidant metabolism. Mn was strongly translocated from the roots to the leaves, triggering a decrease in chlorophyll content. Excess Mn promoted an increase in reactive oxygen species that was accompanied by higher levels of antioxidative enzyme activity and lipid peroxidation. Zea mays L. cv. Saracura efficiently sequestered relatively large amounts of Mn in the leaves, with a significant impact on metabolism; however, we did not observe visual symptoms or a large decrease in biomass production.

ABSTRACT In order to investigate the existence of a possible abscission zone in the binding region between the peduncle and the coffee fruit, as well as the biochemical events involved in fruit ripening, we studied peduncles and fruits of Coffea arabica L. cv. “Icatu amarelo”. Coffee fruits were harvested at different maturation stages by using specific intervals of detachment force. It was observed a breakdown in the cells of the connecting region between peduncles and fruits throughout the maturation process. This disruption is probably caused by increased activity of the cell wall-loosening enzymes (polygalacturonase and cellulase) as well as by higher levels of lipid peroxidation in the final maturation stages. In general, physiological differences between maturation stages were observed and can largely explain the different detachment forces required at different stages. In conclusion, there is no clear abscission zone between the peduncle and the coffee fruit cv. “Icatu amarelo”. Nevertheless, the decrease in the detachment force throughout the maturation process can occur due to the activity of cell wall-degrading enzymes together with increased oxidative stress during the fruit ripening.

<p>A mandioquinha-salsa apresenta-se como grande alternativa de produto minimamente processado, porém pode ser facilmente degradada após as técnicas de processamento. Objetivou-se, neste trabalho, avaliar a vida útil de mandioquinha-salsa, minimamente processada, submetidas a dois tipos de cortes e armazenamento, bem como avaliar a atividade de enzimas antioxidantes. As raízes foram selecionadas, sanitizadas e submetidas a dois tipos de corte: cubos e raladas. Em seguida, foram avaliadas em 3 tempos: 0, 3 e 7 dias. Por meio dos resultados obtidos, foi possível observar que o corte em cubos proporcionou ao produto maior qualidade e menor atividade de SOD, CAT e APX. O produto ralado apresentou maior atividade da PG e menor atividade da PPO. Ambos os cortes apresentaram segurança microbiológica, durante todo o período de armazenamento, além de manterem seu valor nutritivo. Conclui-se que a vida útil, sob os aspectos físico-químicos, nutricionais e microbiológicos, pode ser estabelecida em 7 dias sob refrigeração para mandioquinha-salsa submetida ao processamento mínimo</p>

<p>The arracacha is an alternative of fresh-cut product; however it can be easily degraded after the processing techniques. The objective of this work was to evaluate the useful life of fresh-cut arracacha submitted to two types of cuts and storage, as well as to evaluate the activity of antioxidant enzymes. The roots were selected, sanitized and submitted to two cut types: cubed and grated. Then they were evaluated at 3 times: 0, 3 and 7 days. The cutting in cubes provided higher quality and lower SOD, CAT and APX activity. However, the grated product presented higher PG activity and lower PPO activity. The microbiological safety and the nutritional value were maintained in both cuts during the whole storage period. The useful life, regarding the physicochemical, nutritional and microbiological aspects, can be established at 7 days under refrigeration for fresh-cut arracacha.</p>

A irrigação tem aumentado a produção de café em muitas regiões do Brasil. Entretanto, com o aumento das áreas de produção irrigadas, problemas relacionados à irrigação frequente e mal planejada podem surgir. Em decorrência de poucos estudos ligados às alterações fisiológicas em plantas de cafeeiro submetidas ao excesso de água, avaliaram-se os efeitos do encharcamento no metabolismo e no particionamento de carboidratos, níveis de pigmentos fotossintéticos e trocas gasosas em mudas de duas cultivares comerciais de café (Mundo Novo e Catuaí). Após aclimatação, as mudas, contendo oito pares de folhas completamente expandidas, foram cultivadas em três condições de disponibilidade de água: capacidade de campo, encharcamento intermitente e encharcamento contínuo. As trocas gasosas e os níveis de clorofilas, carotenóides e carboidratos foram avaliados por cinco meses, após o início dos tratamentos. O encharcamento reduziu as taxas de fotossíntese e transpiração, levando a uma menor atividade da etapa carboxilativa da fotossíntese, culminando com a redução do particionamento de carboidratos nas mudas de café. Apesar de os parâmetros analisados terem sido afetados pelo encharcamento, as cultivares deste estudo sobreviveram por cinco meses sob essas condições de estresse.

Irrigation has enhanced coffee production in several regions of Brazil. However, with the increase in irrigated crop areas, problems related to the frequent and poorly planned usage of irrigation may arise. Since there are few studies related to the physiological alterations in coffee plants exposed to water excess, we evaluated the effects of waterlogging on metabolism and partitioning of carbohydrates, levels of photosynthetic pigments and gas exchange in seedlings of two commercial coffee cultivars (Mundo Novo and Catuaí). After acclimation, seedlings with eight pairs of fully expanded leaves were cultivated under three water availability conditions: field capacity, intermittent waterlogging and continuous waterlogging. Gas exchange and the levels of chlorophyll, carotenoids and carbohydrates were evaluated during the five months after the beginning of the treatments. Waterlogging reduced the rates of photosynthesis and transpiration, leading to lower activity of the carboxylative step of photosynthesis and culminating in the reduction of carbohydrate partitioning in coffee seedlings. Although many physiological parameters were affected by waterlogging, the cultivars in our study survived for five months under stressful conditions.

O presente trabalho visou avaliar a interferência do excesso hídrico do solo sobre o crescimento de plantas jovens de café, cultivares Mundo Novo e Catuaí. As mudas foram submetidas a três condições de disponibilidade de água no substrato: controle (mudas irrigadas), encharcamento contínuo do substrato e encharcamento intermitente do substrato. Diversas características de crescimento foram analisadas ao longo de 19 semanas. Baseado no número e qualidade das variáveis afetadas em todas as análises, a cultivar Catuaí mostrou maior sensibilidade ao encharcamento.. Ambas as cultivares de café apresentaram inibição do crescimento em resposta ao estresse por encharcamento do substrato, que foi agravado pela queda prematura das folhas.

The objective of the present study was to evaluate the interference of water excess in soil on the growth of young coffee plants of the Mundo Novo and Catuaí cultivars.Plants were subjected to the following three different substrate water availability conditions: control (wellwatered), continuous substrate waterlogged, and intermittent substrate waterlogged. Several growth-related traits were evaluated over the course of 19 weeks. Based on the number and quality of the affected variables from all forms of analyses, the Catuaí cultivar showed greater sensitivity to waterlogging. Both cultivars exhibited growth inhibition in response to substrate waterlogging stress, which was exacerbated by premature leaf dropping.