The successful use of native species in conservation actions depends on basic knowledge of their biology, beginning with the identification of regenerating individuals in the field, up to the behavior and development of the species from the early stages of germination. Moreover, seed propagation and germination may be limited by the occurrence of dormancy. The objective of this work was to identify the best method to overcome seed dormancy of Hymenaea parvifolia Huber, besides characterizing the fruits, seeds, post-seminal development and seedlings of naturally occurring specimens in Amazonia. For this, (i) tests for the breakdown of dormancy were performed through thermal, chemical and mechanical treatments; (ii) analyses of their effects on seed germination were made; and (iii) morphology of germinative development of Hymenaea parvifolia was described. The treatments based on sulfuric acid for 15, 25 and 35 minutes were the most efficient in overcoming the integumentary dormancy. However, scarification by grinding is recommended because it had been less impact on the environment. External characteristics and shape of the fruit, seed and epicotyl can aid taxonomy of the genus and identification of its species in the field. In addition, morphological characters of the fruit, seed, germination and seedling were illustrated.

Plectranthus ornatus is a medicinal and aromatic plant used in traditional and alternative medicine. In this study, leaves of P. ornatus were collected in two cities of the state of Pará, “Quatipuru” and “Barcarena”, and were used with the objective of analyzing, through morphoanatomical data and histochemical and phytochemical studies of essential oil, the samples present structural differences and differences in their chemical composition. Anatomical and histochemical analyses were performed by transverse, using longitudinal sections of 8 μm to 10 μm to perform epidermal dissociation, diaphonization, and tests to identify classes of secondary metabolites. The essential oils were isolated by hydrodistillation, and the identification of the chemical composition was performed by gas chromatography coupled with mass spectrometry. The anatomical study shows that there is no difference between specimens collected in different locations, and stellate trichomes were identified. The histochemical study detected total lipids and acids, terpenes, polysaccharides, phenolic compounds, tannins, alkaloids, and calcium oxalate. The low essential oil yield may be related to the low density of secretory cells (glandular trichomes), the unidentified compounds in the highest concentration in the essential oil were in relation to the chemical composition of the essential oils, and the major compounds were α-pinene, sabinene, (E)-caryophyllene, caryophyllene oxide, and oct-1-en-3-ol. The results provide new information about the anatomy and histochemistry of P. ornatus.

Determining the optimal harvest time for Pentaclethra macroloba seeds is essential to preserve germination potential and ensure high-quality oil production, valued in the pharmaceutical and cosmetic industries. This study aimed to identify the maturation phase that maximizes seed physiological quality and oil yield. Fruits and seeds were collected from 44 mother plants in Belém and São Domingos do Capim, Brazil, during three final maturation phases: P1 (dark green pericarp, beige seeds), P2 (yellowish-green pericarp, light-brown seeds), and P3 (black pericarp, dark brown seeds). Germination, vigor tests, and gas chromatography analyses revealed that seeds from P3 exhibited the highest vigor (93–99% germination) and oil yield (up to 13.1%). Major fatty acids were oleic (up to 65.23%), linoleic (up to 8.45%), and behenic acids (up to 17.22%). The ripening period ranged from 7 to 8 months, influenced by environmental factors. Optimal seed quality and oil yield are achieved when harvesting occurs before dispersal, targeting fruits with yellowish-green pericarp transitioning to black. Post-harvest drying enhances oil extraction efficiency. These findings support the conservation of P. macroloba through viable seeds and promote economic sustainability by optimizing oil production, benefiting biodiversity and local extractive communities.

Pentaclethra macroloba (Willd.), whose common name is pracaxi, is naturally found in the Amazon region. The present study is aimed at analyzing the anatomy, seed histochemistry, and chemical composition in fatty acid profile of P. macroloba seed oils. Seeds were collected in the cities of Belm, Marituba, and So Domingos do Capim-PA. For the study in light microscopy, scanning electron microscopy, and histochemistry, seeds were sectioned in cross and longitudinal sections of the embryonic axis and fixed in formaldehyde, acetic acid, and 50 ethyl alcohol; neutral-buffered formalin; and formaldehyde and ferrous sulfate and stored in 70 ethyl alcohol. For the anatomical study, the seeds were subjected to the usual techniques of plant anatomy. Histochemical tests were performed on plant material, freehand sectioned, and embedded in histological paraffin with DMSO. The fatty acid profile was determined for gas chromatography (GC-FID). Integument is divided into three strata, monoseriate exotesta, mesotesta formed by several layers of parenchyma cells, and monoseriate endotesta, formed by compressed cells. Cotyledons are composed of thin-walled parenchyma cells with several secretory cavities and secretory idioblasts. The main metabolic classes are lipids, phenolic compounds, carbohydrates, proteins, and alkaloids. The main fatty acids found in P. macroloba oil are oleic, behenic, lignoceric, and linoleic. P. macroloba seeds have important anatomical characteristics for their circumscription in Leguminosae and also in Caesalpinioideae, and their oil is rich in fatty acids essential to the human diet, providing many benefits to the human health, such as fatty acids belonging to the omega family (linoleic, oleic).

O milheto (Pennisetum glaucum L.) é uma gramínea anual da família Poaceae, adaptada ao clima tropical, amplamente utilizada para produção de grãos, forragem e biomassa. A germinação de sementes dessa espécie pode ser influenciada por fatores ambientais, entre os quais a luz exerce papel importante, atuando na superação da dormência e caracterizando o fenômeno denominado fotoblastismo. Diante disso, este estudo teve como objetivo avaliar o comportamento fotoblástico de sementes de milheto submetidas a diferentes condições de luminosidade. Foram utilizadas duas cultivares (C1 e C2) em delineamento inteiramente casualizado, em esquema fatorial 2 × 5, com quatro repetições de 50 sementes. Os tratamentos consistiram em diferentes espectros de luz: azul (450 nm), verde (500 nm), vermelha (700 nm), ausência de luz (papel laminado) e controle com luz branca (380–760 nm). O teste de germinação foi conduzido durante sete dias em câmara B.O.D a 25 °C, com fotoperíodo de 12 horas. Avaliaram-se a porcentagem de germinação, índice de velocidade de germinação (IVG), comprimento da parte aérea, raiz, total e massa fresca e seca das plântulas. Os resultados foram analisados pelo teste de Tukey a 5% de probabilidade. Observou-se que os diferentes filtros de luz não influenciaram significativamente a germinação nem a maioria dos parâmetros de vigor das sementes. Apenas a primeira contagem de germinação e o comprimento da raiz apresentaram diferenças entre tratamentos. Conclui-se que as sementes de milheto apresentam comportamento fotoblástico neutro, sendo capazes de germinar tanto na presença quanto na ausência de luz.