Sttela Dellyzete Veiga Franco da Rosa

Effects of different drying rates on the physiological quality of Coffea canephora Pierre seeds

Desiccation tolerance in seeds depends on the species, development stage and drying conditions, especially the water removal rate. Coffea seeds are considered of intermediate performance, because they tolerate relative dehydration compared to orthodox seeds and are sensitive to low temperatures. The objective of this study was to verify the effect of different drying rates on the viability and storability of Coffea canephora seeds. A complete randomized experimental design was used, in a factorial 3 x 5 x 2 design, with three drying rates (fast, intermediate and slow), five final mean water contents after drying (51, 42, 33, 22 and 15 %) and two storage temperatures (10 and 20°C). The germination and seed vigor assessments, using radicle protrusion, cotyledon leaf opening, seedling emergence and emergence speed index, were performed shortly after drying and after two and four months storage. It was observed that with reduction in the water content there was reduction in the germination values and seed vigor, for all the drying rates. The greatest reductions in physiological quality occurred when the seeds were dried quickly and the best results were obtained at the intermediate drying rate. There was an effect of drying rate and storage temperature on the physiological quality of the seeds, and lower germination and vigor values were observed in seeds with lower water content stored at 20°C. C. canephora seeds were tolerant to desiccation down to 15 % water content and can be stored for four months at 10°C. A temperature of 20oC can be used to store C. canephora seeds, as long as the water content is not reduced to values below 22 % water content.

Armazenabilidade de sementes de cafeeiro colhidas em diferentes estádios de maturação e submetidas a diferentes métodos de secagem

The harvesting time and drying methods may influence the quality of coffee seeds during storage. This work was conducted with the objective of understand the effects of maturation stages and drying methods on the physiological quality and storability of coffee seeds. The experiments were performed at the Seed Analysis and Electrophoresis Laboratory of the Department of Agricultural of UFLA. The fruits of the cultivar Rubi were harvested, depulped and the mucilages removed by fermentation and the seeds washed and let on paper for removal of the water. The seeds were submitted to conventional drying (under shade) and drying in stationary drier at temperature of 35oC. As a control, seeds with no drying were analyzed. The evaluations were done soon after the drying treatments and after four and eight months of storage. The seeds were stored at 10oC in air-tight plastic packages. The germination test, radicle protrusion, seedling dry matter, emergence index speed, electric conductivity, electrophoresis analyses of heat-resistant proteins and quantification of endo-â-mannanase activity were the parameter evaluated. The design was completely randomized with 2 (maturation stages) x 3 (dryings) x 3 (storage time) factorial scheme with four replications. Seeds harvested in the cherry stage have greater storage potential than in the green-yellow stage. Reduced germination and vigor occur in the coffee seeds harvested in the green yellow stage, when submitted to fast drying. The presence or intensity heat-resistant protein bands is associated with seed drying. Greater activity of endo-s-mananase enzyme occurs in seeds harvested in the cherry stage than in the green yellow stage. Increase of the activity of endo-s-mananase enzyme occurs during storage.

Tolerância de sementes de soja à dessecação

A colheita antecipada de sementes, apos a maturidade fisiologica, permite a obtencao da melhor qualidade fisiologica e sanitaria, rotacao de culturas e otimizacao das estruturas de processamento. Sementes nao toleram a secagem durante todos estadios e adquirem tolerância em estadios especificos. Durante a maturacao, esta aquisicao da tolerância a dessecacao pode coincidir com a maturidade fisiologica e, em sementes de soja, ocorre no estadio R7, com umidade ao redor de 45% a 50%. Assim, a presente pesquisa teve como objetivo avaliar a tolerância a dessecacao de sementes de soja. As sementes foram colhidas em tres estadios fenologicos, R6, R6/R7 e R7 e foram submetidas a secagem artificial a 35oC ate 20% de teor de agua e a 42oC ate 13%. Uma quarta colheita foi realizada com sementes secadas no campo, sendo estas utilizadas como testemunha. A qualidade das sementes foi avaliada pelos testes de germinacao, de condutividade eletrica, de frio, de peso seco de plântulas e eletroforese de proteinas lea. O delineamento experimental foi inteiramente casualizado em esquema fatorial com quatro repeticoes. A testemunha foi comparada individualmente com cada tratamento. Com os resultados, concluiu-se que a germinabilidade e a tolerância a dessecacao de sementes de soja aumentam com a perda natural de agua no campo; sementes colhidas no estadio R7 apresentam maior qualidade fisiologica, padrao diferenciado de proteinas lea e maior tolerância a dessecacao do que nos estadios R6 e R6/R7; secagem de sementes colhidas proximo a maturidade induz a sintese de lea proteinas; e sementes colhidas no estadio R7 apresentam qualidade fisiologica e padrao de proteina lea similares aos de sementes secadas no campo ate 14% de teor de agua.

Activity of some isoenzymatic systems in stored coffee grains.

Considering the worldwide consumption of coffee, it is natural that throughout the history many people have dedicated the research to markers that contribute somehow on gauging its quality. This research aimed to evaluate the biochemical performance of arabica coffee during storage. Coffee in beans (natural) and in parchment (pulped) dried in concrete terrace and in dryer with heated air were packed in jute bags and stored in not controlled environmental conditions. Enzymatic activities of superoxide dismutase, catalase, peroxidase, polyphenoloxidase, esterase and lipoxygenase in coffee grains were evaluated at zero, three, six, nine and twelve months by means of electrophoresis. Independently of the drying method, the activity of isoenzymatic complexes highlighted deteriorative processes in stored grains of coffee. The treatments 60/40o C and 60o C used to reduce the water content imposed a greater stress condition, accelerated metabolism of natural coffee in the storage with decreased activity of defense mechanisms due to latent damage in these grains. Natural coffees are more sensible to high drying temperatures and its quality reduces faster than pulped coffee in the storage.

Perfis proteicos e desempenho fisiológico de sementes de café submetidas a diferentes métodos de processamento e secagem

The objective of this work was to evaluate the protein profiles and physiological performance of coffee seeds subjected to different drying and processing methods. We evaluated processing by dry and wet routes, the drying methods: natural, on the patio, and artificial at 60oC, or at 60oC until 30% of moisture content and 40oC until 11% (wet basis). After processing and drying, the seeds were evaluated as to their physiological performance and subjected to biochemical analyses with electrophoresis of heat‑resistant LEA (late embryogenesis abundant) proteins and of the enzymes superoxide dismutase, catalase, peroxidase, esterase, polyphenol oxidase, isocitrate dehydrogenase, alcohol dehydrogenase, and malate dehydrogenase. The protein profile of coffee seeds is affected by the processing and drying methods. The coffee processed by wet route has higher tolerance to drying - shown by the higher activity of antioxidative enzymes and better physiological performance - than that processed by dry route. The activity of heat‑resistant proteins and antioxidant enzymes is a promising variable for the differentiation of the quality of coffee subjected to different postharvest management.

Inibição do desenvolvimento in vitro de embriões de Coffea por cafeína exógena

Caffeine, the alkaloid known as 1,3,7 - trimetilxantina, is found in quiescent coffee seeds, amounting to a total of 1.1 to 1.7% in Coffea arabica L. and 2 to 3% in Coffea canephora Pierre, mostly localized in theo endosperm, in the free cytoplasm of cells or complexed with chlorogenic acids. With the physiological function in plants not yet completely understood, caffeine causes an allelophatic effect, either inhibiting germination of a number of species or as an anti-herbivore or a natural pesticide agent. The slow germination of coffee seeds has not yet been elucidated and several causes are pointed to, such as the presence of the endocarp, low water and O2 uptake and presence of natural inhibitors and hormonal balance. Although suggested, studies on coffee seed inhibition by the action of endogenous or exogenous caffeine are scarce. Thus, the present study was designed to investigate the effect of exogenous caffeine on both germination and embryo development of Coffea arabica L. and Coffea canephora Pierre. The experiment was conducted by utilizing seeds from red ripe berries of the cultivars Rubi and Apoata IAC-2258. After disinfecting the berries for 30 minutes by soaking in sodium hypochlorite (2% a.i.) and washing three times in distilled water and autoclaved, the embryos were removed and inoculated in a aseptic manner, in Petrri dishes with 50% MS medium with the addition of sucrose and supplemented with different of concentrations of caffeine (0.00; 0.05; 0.10; 0.15; 0.20; 0.25; 0.30 and 0.40%). The embryos were maintained in a growth room at 27±20oC and photon flow density of 13µmol.m-2.s-1 for 23 days, when shoot length, root length and seedling fresh mass were evaluated. Five days after cultivation, the percentage of radicle emission and that of cotyledons were evaluated, calculating the embryos with open cotyledons and with expanded radicles. A complete randomized experimental design was used six replications per treatment, each replicate consisting of five embryos. It follows that germination and in vitro development of embryos of Coffea arabica L. and of Coffea canephora Pierre are affected by exogenous caffeine. The detrimental effect of exogenous caffeine on Coffea embryos is greater on the radicles than on the cotyledons. Coffea arabica L. embryos are more sensitive to the negative effects of exogenous caffeine than embryos of Coffea canephora Pierre. Caffeine can contribute to the slow seed germination and slow coffee seedling development.

Alterações fisiológicas e bioquímicas em sementes de café secas em sílica gel e soluções salinas saturadas

O objetivo deste trabalho foi avaliar alteracoes fisiologicas e bioquimicas em sementes de cafe submetidas a secagem rapida, em silica gel, e a secagem lenta, em solucoes salinas saturadas. As sementes foram secas ate que atingissem os seguintes teores de agua: 40, 30, 20, 15, 10 e 5% (base umida). Apos a secagem, uma parte das sementes foi imediatamente avaliada quanto ao desempenho fisiologico e ao perfil de enzimas do processo oxidativo, e outra parte foi avaliada apos armazenagem em condicao hermetica, em câmara fria e seca, por quatro meses. A velocidade de secagem e o teor final de agua tiveram efeito significativo sobre a qualidade fisiologica das sementes. Apos a secagem rapida em silica gel, as sementes toleraram teores finais de agua mais baixos. No entanto, apos a secagem lenta, as sementes com teores finais de agua mais elevados apresentaram maior qualidade. O periodo de armazenamento nao afetou a germinacao, mas prejudicou o vigor das sementes. A secagem rapida apresenta maior potencial de dano ao endosperma do que aos embrioes. O perfil enzimatico das sementes de cafe e afetado pelo teor final de agua e pela velocidade de secagem.

Influence of lignin content in soybean seed coat on the incidence of the storage fungus Aspergillus flavus

Seed quality may be affected by several factors, including permeability, color, and lignin content in the seed coat. This study aimed at evaluating influence of lignin content in the tegument of seed samples of six different soybean cultivars, in which half of each sample was inoculated with the fungus Aspergillus flavus, on the physical and physiological quality, and on the seed health, during 180 days storage period, under cold chamber with controlled conditions of temperature and RH. For that, at each interval of 60 days, samples were removed, and the physiological quality of these seeds was assessed by means of moisture and lignin contents; and by tests of seed health, germination, and electrical conductivity. The moisture content of seeds remained constant during all storage period. In the seed health test, it was found that inoculation was efficient, once the minimum incidence of the fungus in the inoculated seeds was 85%. In the germination test, there was a trend of reduction on percentage germination with the increase in storage period. However, there was an increase on electrical conductivity of seeds assessed. It was concluded that there is no interference of the lignin content in the seed coat on the resistance to infection by the fungus Aspergillus flavus, even after seed storage for a period of 180 days.

Physiological quality of coffee seeds produced under different levels of solar radiation and maturation stages

In Brazil, although the coffee plantations are predominantly grown under full sunlight, the use of agroforestry systems can lead to socioeconomic advantages, thus providing a favorable environment to the crop by promoting its sustainability as well as environmental preservation. However, there is a lack of information on physiological quality of the coffee seeds produced under different levels of solar radiation. Within this context, the objective of this study was to evaluate the influence of different levels of solar radiation and maturation stages on the physiological quality of coffee (Coffea arabica L.) seeds, cv. Acaia Cerrado MG-1474. Three levels of solar radiation (plants grown under full sunlight; under plastic screens of 35% shading; and under plastic screens of 50% shading) and three maturation stages (cherry, greenish-yellow and green) were assessed. Physiological quality of seeds was assessed by using germination test, first count of germination, abnormal seedlings, dead seeds, and seedlings with open cotyledonary leaves. Electrophoretic analysis of isoenzymes catalase, esterase, superoxide dismutase and peroxidase was also performed. With the evolution of development the coffee seeds presents increases on physiological quality, and at its beginning the seeds show improvements on quality with the reduction of solar radiation.

Delayed Luminescence in Relation to the Germination and Vigour of Coffee Seeds: Initial Series with C. Arabica Samples

Ultra-weak delayed luminescence measurements on coffee seeds were run for samples submitted to different post-harvest treatments or in seed lots with different vigour levels obtained by accelerated aging, and both were induced to germinate afterwards. Parameters of hyperbolic decay fitting were correlated to the correspondent germination vigour, with a linear relation found for the initial value as well as for the decay velocity. These preliminary data point to further, broader validation for this non-invasive, non-destructive test for seed’s viability analyses.