ABSTRACT The deterioration process of recalcitrant seeds is not fully known, mainly regarding the relation between fungi activity and respiration. Inga vera seeds are characterized by their high degree of sensitivity to desiccation and for only maintaining viability for a few weeks. The objective of this study was to identify the fungus action on respiratory metabolism of I. vera embryos subjected to chemical treatment in order to extend their storability. The results showed that the presence of fungi increases embryo respiration rate, thus affecting their conservation during storage. Treatment with carbendazin + thiram, especially at a dose of 200 ml per each 100 kg of seeds, was effective in controlling fungi, reducing the respiration rate and metabolism of I. vera embryos, increasing the maintenance period of their viability in storage.

RESUMO A uvaieira (Eugenia pyriformis Cambess.), espécie arbórea e frutífera, com potencial farmacológico e gastronômico, apresenta sementes sensíveis à dessecação. O objetivo deste trabalho foi analisar se o grau de tolerância à dessecação de sementes de uvaieira depende do grau de maturidade das sementes no momento de sua dispersão. Este, por sua vez, depende das condições ambientais nas quais as sementes se desenvolvem, incluindo-se o acúmulo de graus-dia e a chuva acumulada no período. As sementes foram coletadas de frutos maduros de matrizes localizadas em São Paulo e Minas Gerais, submetidas à secagem e analisadas quanto ao teor de água e germinação. Utilizou-se o delineamento inteiramente casualizado, em esquema fatorial 20 x 3 (origem do material x níveis de secagem). O grau de tolerância à dessecação difere entre as regiões e épocas de coleta, inclusive dentro da mesma matriz, quando as sementes são coletadas em anos distintos. As condições hídricas e térmicas do ambiente, durante o desenvolvimento das sementes, condicionam o ciclo de maturação, a qualidade fisiológica e a aquisição da tolerância à dessecação. A tolerância à dessecação de sementes de uvaieira depende da maturidade fisiológica das sementes no momento de sua dispersão, a qual está associada às condições ambientais.

ABSTRACT Eugenia pyriformis Cambess., known locally as uvaieira, a species of fruit-bearing tree with both pharmacological and gastronomic potential, has seeds which are sensitive to desiccation. The aim of this study was to analyse whether the degree of tolerance to desiccation of uvaieira seeds depends on the stage of maturation of the seeds at shedding. This, in turn, depends on the environmental conditions in which the seeds develop, including the accumulation of degree-days and rainfall in the period. Seeds were collected from the ripe fruit of parent plants located in the states of São Paulo and Minas Gerais, Brazil, submitted to drying and analysed for water content and germination. A completely randomised design was used in a 20 x 3 factorial scheme (source of material x level of drying). The degree of desiccation tolerance differs between region and period of collection, even for the same parent plant when the seeds are collected in different years. The water and thermal conditions of the environment during seed development modify the maturation cycle, the physiological quality and the acquisition of desiccation tolerance. In uvaieira seeds, desiccation tolerance depends on the physiological maturity of the seeds at the time of dispersal, which is associated with the environmental conditions.

Ingá, espécie nativa do Brasil utilizada na arborização urbana e em sistemas agroflorestais, tem sementes altamente sensíveis à dessecação. Essa sensibilidade pode ser condicionada pelas condições ambientais em que as sementes são formadas. Neste estudo, analisou-se o grau de sensibilidade à dessecação de embriões de ingá de origens distintas e formados sob diferentes condições ambientais. Os embriões foram obtidos de frutos maduros de matrizes em São Paulo e Minas Gerais e analisados quanto ao teor de água e conteúdo de massa de matéria seca no momento da dispersão e quanto ao grau de sensibilidade à dessecação. Os resultados confirmaram a hipótese de que a sensibilidade à dessecação não é totalmente predeterminada para as sementes de uma espécie e pode apresentar variações conforme a região de procedência. Verificou-se, ainda, que as condições do ambiente, principalmente temperatura do ar e disponibilidade hídrica, podem condicionar o ciclo de maturação, o grau de maturidade dos embriões após a dispersão dos frutos, a aquisição da tolerância à dessecação e a qualidade final dos embriões.

ABSTRACT "Ingá", a brazilian species commonly used in urban forestation and in agroforestry systems, produces seeds highly sensitive to desiccation. This sensitivity can be influenced by environmental conditions during seed formation. In this study we analyzed the degree of sensitivity to desiccation of ingá embryos obtained from different origins and environmental conditions. Embryos were obtained from mature fruits of trees in São Paulo and Minas Gerais and were analyzed for both water and dry matter content at shedding, as well as the degree of their sensitivity to desiccation. The results confirmed the hypothesis that the sensitivity to desiccation of seeds is not totally pre-established for the seeds of a species and may vary according to region in which they were obtained. It was also found that the conditions of the environment, especially air temperature and water availability can influence the maturation cycle, the degree of maturity of the embryos at shedding, the acquisition of desiccation tolerance and the final quality of the embryos.

Annona emarginata (Schldtl.) H. Rainer ("araticum-de-terra-fria") is used as a rootstock for several species of Annonaceae. It is suggested that these seeds should be sown immediately after extraction and, therefore, they could be intolerant to desiccation. There are several mechanisms involved with desiccation tolerance. Soluble sugars, for example, can accumulate and act as osmoprotectants for the membrane system during desiccation. The aim of this study is to assess desiccation tolerance in A. emarginata seeds. In addition, we examined the soluble sugars involved in desiccation tolerance. Finally, we determined the effect of gibberellic acid (GA4+7) and N-(phenylmethyl)-aminopurine in promoting the germination of seeds with different water contents. The experiment consisted of a randomized 4x5 factorial design (desiccation levels x concentration of growth regulators). After drying, seeds containing 31 (control), 19, 12 and 5% water were incubated in different concentrations of GA4+7 N-(phenylmethyl)-aminopurine (0, 250, 500, 750 and 1000 mg L-1) for 60 hours. The experiment was conducted in a germination chamber with alternating temperature and photoperiod of 20ºC for 18 hours of darkness and 30ºC for 6 hours of light. We analyzed electrical conductivity, germination rate, mean germination time, germination speed, frequency and uniformity of germination, percentage of dormant seeds and soluble sugar profile in intact seeds through high-performance liquid chromatography (HPLC). The data were subjected to analysis of variance, and the means were compared using Tukey's test at a threshold of p<0.05. The results showed that seeds of A. emarginata appears to be desiccation tolerant and, also, that sucrose increases when seed water content is reduced to values as low as 12%, exogenous GA4+7+N-(phenylmethyl)-aminopurine improves its germinability.

Estudos de germinação após o fracionamento de sementes monoembriônicas de diversas espécies de Eugenia demonstraram seu potencial regenerativo. Entretanto, a formação de novas plântulas não ocorre de maneira espontânea em sementes intactas, sugerindo a presença de inibidores de germinação na semente germinante. Para investigar a presença de possíveis inibidores, seis concentrações de extratos de sementes de pitangueira (Eugenia uniflora) foram utilizados em testes de germinação, além do controle (água pura). O possível efeito osmótico desses extratos foram aferidos com soluções de PEG 6000 e de NaCl, de -0,05 a -0,40 MPa. Os extratos de pitanga não apresentaram inibição de germinação para a própria espécie. Contudo, para aquênios de alface e para sementes de feijão os resultados apresentaram diferenças significativas, revelando potencial inibidor da germinação e do desenvolvimento inicial das plântulas. Simulando-se os potenciais hídricos dos extratos de pitanga que causaram inibição da germinação, quando as soluções foram preparadas com PEG 6000 houve semelhante inibição, mas não quando as soluções foram preparadas com NaCl. Esta diferença de comportamento apresentada pelos diferentes solutos sugere que soluções de PEG 6000 resultem em alterações não apenas do potencial hídrico.

Germination studies of sectioned seeds of Eugenia species demonstrated their potential for regeneration. However, new seedlings are not spontaneously produced by intact seeds, suggesting the presence of germination inhibitors in the seed. Germination tests were made with six extracts prepared from Surinam cherry seeds (Eugenia uniflora) with pure water as the control. The osmotic effects of these extracts were also investigated using solutions of both PEG 6000 and NaCl, varying from -0.05 to -0.4 MPa. Surinam cherry seed extracts did not inhibit germination of the species itself but they showed a potential for inhibiting germination and normal seedling development in lettuce and dry beans. Considering osmotic potentials similar to those of the inhibiting extracts, PEG solutions produced similar effects, but this was not observed for the NaCl solutions. This difference in behavior by the different solutes suggests effects other than osmotic ones for PEG solutions.