ABSTRACT Ferruginous Rocky Outcrops have high levels of species richness and endemism, but have been threatened by several anthropic actions, especially mining. Eragrostis polytricha, a common grass species in the vegetation of these outcrops, has shown promising features for use in the recovery of mining areas. However, in order to fully understand the species’ potential for such use, its requirements for germination, seed dormancy break and seedling development must be determined. Thus, we aimed to: (1) assess the temperature conditions needed for seeds of E. polytricha to germinate; (2) evaluate the effects of KNO₃ in breaking seed dormancy; and (3) analyze the germination efficiency of seeds that are still in spikelets. The experiment included seven treatments: 15-35 ºC with KNO₃, 20-30 ºC with KNO₃, 15 ºC with KNO₃, 25 ºC with KNO₃, 35 ºC with KNO₃, 20-30 ºC with water, and 20-30 ºC with KNO₃ using spikelets. The treatments with alternating temperatures associated with KNO3 yielded the highest germination rates, suggesting that these two factors combined can break seed dormancy. Seeds inside spikelets exhibited a high germination percentage, and thus represent an interesting alternative for seedling production.

Abstract New approaches based on image analysis can assist in phenotyping of biological characteristics, serving as support for decision-making in modern agribusiness. The aim of this study was to propose a method of high-throughput phenotyping of free access for processing of 2D X-ray images of brachiaria grass (Brachiaria ruziziensis cv. Ruziziensis) seeds, as well as correlate the parameters linked to the physiological potential of the seeds. The study was carried out by means of automated analysis of X-ray images of seeds in which a macro, called PhenoXray, was developed, responsible for digital image processing, for which a series of descriptors were obtained. After the X-ray analysis, a germination test was performed on the seeds and, from this, variables related to the physiological quality of the seeds were obtained. The use of the macro PhenoXray allowed large-scale phenotyping of seed X-rays in a simple, rapid, robust, and totally free manner. This study confirmed that the methodology is efficient for obtaining morphometric data and tissue integrity data in Brachiaria ruziziensis seeds and that parameters such as relative density, integrated density, and seed filling are closely related to the physiological attributes of seed quality.

ABSTRACT The physical, physiological and biochemical changes during the development until the dispersal of rubber tree seeds were evaluated with the purpose of estimating the point at physiological maturity. A total of 30 plants were selected at different points in a commercial planting area and had their flowers marked during the anthesis and every 15 days after marking. Fruits and seeds were collected for analysis of moisture content, dry matter, diameter and length. Details of the anatomy ultra-structure of the seeds were evaluated. The seed emergence, emergency speed index, heat resistant proteins and oxidative stress enzymes were examined. It was observed that fruits reached maximum size at 120 days after anthesis and seeds at 150 days. The seeds acquired germination capacity after 150 days. At 175 days, they presented the highest percentage of dry matter and lowest moisture, in addition to a higher percentage of germination and vigor. Therefore, it was possible to conclude that the physiological maturity of the rubber tree seeds occurs at 175 days after anthesis, and coincides with its maximum physiological quality. At 175 and 180 days post-anthesis, there is a greater expression of heat resistant proteins as well as low molecular weight and greater oxidative stress enzyme activity.

RESUMO Nós investigamos a perda da tolerância à dessecação (TD) em sementes deAdenanthera pavonina durante a germinação. Sementes submetidas à embebição por 0, 24, 36, 48, 60 e 81 h foram secas até à umidade inicial (13%), reidratadas e avaliadas quanto à sobrevivência (retomada do crescimento e formação de plântulas normais) e à integridade do sistema de membranas (extravasamento de eletrólitos). Eixos embrionários de sementes submetidas apenas à embebição, pelos mesmos tempos citados anteriormente, foram utilizados para avaliar os padrões eletroforéticos de proteínas resistentes ao calor e o conteúdo relativo de DNA nuclear. Em sementes de A. pavonina, a TD foi mantida por até 36 h de embebição (resultando em germinação e 82% de plântulas normais), após o que foi gradativamente perdida, até que sementes com 1 mm de raiz primária não sobreviveram após a secagem. A perda da TD não pôde ser correlacionada com danos causados por secagem ao sistema de membranas, nem com a retomada do ciclo celular durante a germinação. No entanto, a redução do conteúdo de proteínas resistentes ao calor, ao longo da germinação, pode estar relacionada com a perda da TD em sementes de A. pavonina.

ABSTRACT We investigated the loss of desiccation tolerance (DT) in Adenanthera pavonina seeds during germination. Seeds were subjected to imbibition for 0, 24, 36, 48, 60 and 81 h, then dried to their initial moisture content (13%), rehydrated and evaluated for survival (resumption of growth and development of normal seedlings) and membrane system integrity (electrolyte leakage). Embryonic axes of seeds subjected only to imbibition during the same early time periods were used to investigate the electrophoretic patterns of heat-stable proteins and the relative nuclear DNA content. In A. pavonina seeds, DT remained unchanged until 36 h of imbibition (resulting in germination and 82% normal seedlings), after which it was progressively lost, and seeds with a protruded radicle length of 1 mm did not withstand dehydration. The loss of desiccation tolerance could not be related to either membrane damage caused by drying or the resumption of the cell cycle during germination. However, the decrease in heat-stable protein contents observed throughout germination may be related to the loss of DT in A. pavonina seeds.

A técnica "Random Amplified Polymorphic DNA" (RAPD) surgiu como uma ferramenta útil para testar a pureza genética e a discriminação de cultivares em muitas espécies. É uma técnica simples, rápida, relativamente de baixo custo e permite o uso de DNA extraído de sementes secas, o que é muito importante em um programa de análise de sementes. O uso desta tecnologia no teste da pureza genética pode ser muito interessante para algumas espécies, como a vinca (Catharanthus roseus (L.) G.Don), pois pouco se conhece a respeito da seqüência de seu DNA. É interessante, também, pelo fato de existir grande número de "primers" comercialmente disponíveis, que podem ser prontamente utilizados para gerar dados. Essa técnica pode ser mais facilmente utilizada para gerar padrões de bandas polimórficas suficientes para discriminar genótipos diferentes. Todavia, no presente estudo, os padrões RAPD de bandas obtidas de amostras de DNA extraído de sementes de vinca em "bulk" foram não-consistentes, o mesmo ocorrendo com o uso de DNA extraído de sementes individuais de um mesmo cultivar, o que evidencia que a técnica não é aplicável para testar a pureza genética e a discriminação de cultivares de vinca. Entretanto, os padrões de bandas RAPD gerados a partir de DNA extraído de tecido foliar de plântulas foram mais reproduzíveis e poderiam ser considerados na caracterização de cultivares.

The Random Amplified Polymorphic DNA (RAPD) technique appears useful for genetic purity testing and variety discrimination for several crops. It is simple, fast, relatively inexpensive and allows the use of DNA extracted from dry seeds, which is important in a seed-quality testing program. This genetic purity testing approach may be very attractive for species such as vinca (Catharanthus roseus (L.) G.Don) because little is known concerning the DNA sequence and a number of commercial primers can be utilized to achieve polymorphic banding patterns to discriminate genotypes. However, in this study, RAPD banding patterns obtained from bulked vinca seed were not consistent. Similar inconsistent results were found for RAPD banding patterns of individual vinca seeds from the same cultivar. Thus, the low stringency requirements of RAPDs may be responsible for these irreproducible and unexpected results. In addition, this highly sensitive technique still requires further standardization of test protocol. These findings suggest that RAPD fragments obtained on electrophoretic gels are not applicable for genetic purity testing and variety discrimination in vinca flower seeds. However, RAPD banding patterns acquired from seedling leaf tissue of vinca were more reproducible.