Seeds

The Neotropical Savanna (Cerrado) is a fire-prone biome characterized by seasonal climate, nutrient-poor soils, and variable fire regimes. While fire-induced germination responses are well documented in Cerrado plants, the role of seed size in mediating thermal tolerance remains poorly understood. Here, we investigate how seed size and fire-related heat treatments influence germination in Hymenaea stigonocarpa, a keystone Cerrado tree species. Specifically, we test the predictions that (i) low to moderate fire temperatures (<270 °C) do not impair seed germination and (ii) larger seeds exhibit greater heat tolerance than smaller seeds. We exposed 360 seeds from 30 individual trees to five heat-shock treatments (27, 100, 150, 200, and 270 °C) simulating fire intensities typically experienced in the Cerrado. Our results show that H. stigonocarpa produces relatively large seeds with an average germination rate of approximately 42%. The average time required for germination was 12.18 ± 0.43 (average ± standard error) days. The time required for seed germination varied significantly as a function of heat-shock treatment and seed mass, with seeds exposed to the highest temperature (270 °C) taking longer to germinate. Moreover, seed mass had a positive effect on the time required for seed germination. The germination percentage remains stable across heat treatments and seed sizes, indicating that H. stigonocarpa seeds exhibit characteristics typical of heat-tolerant species rather than those of heat-stimulated species. Our study showed that H. stigonocarpa trees produce large seeds that germinate quickly and are tolerant to moderate temperatures. These seed traits play a crucial role in the reproductive success of individual plants in fire-prone, nutrient-poor, and water-limited ecosystems. Furthermore, our results offer important guidance by emphasizing the role of seed size in effective restoration initiatives.

A sustainable economy and the drive to reduce agro-industrial waste worldwide motivate the increased interest in alternative uses of traditionally cultivated plants such as tobacco. Tobacco seeds are an underutilized resource with enormous potential for application in various areas of human life. The present study aims to characterize the phytochemical composition and nutritional potential of Oriental tobacco seeds grown in Bulgaria, in order to support their possible application in areas outside the tobacco industry. Two Oriental tobacco varieties (“Krumovgrad 90” and “Krumovgrad 58”) from three production regions were explored and comparatively evaluated in terms of their physical and chemical indicators, determined by standardized methods. The results showed high protein (22.57–23.84%) and energy content (482–531 kcal/100 g), combined with relatively low carbohydrate levels (3.79–4.03%) and the presence of bioactive compounds, such as polyphenols (288–357 mg GAE/100 g). The seeds contained significant amount of oil (36.31–39.24%), of which the fatty acid profile included 16 identified components, with linoleic (72.0–74.4%), oleic (11.2–13.5%), palmitic (9.6–10.2%), and stearic (1.8–2.5%) acids taking the greatest share. The sterol fraction was dominated by β-sitosterol (43.5–46.8%), followed by sitostanol, campesterol and stigmasterol, with a stable distribution between the samples. The main tocol was γ-tocotrienol (56.5–61.4%), with α-tocotrienol being detected only in one of the varieties (“Krumovgrad 58”, 13.3%). The phospholipid fraction showed variations between the samples, with a dominant presence of phosphatidylinositol (18.0–20.4%). The results from the study confirmed the tangible potential of tobacco seeds as a source of biologically active substances in the development of functional foods and dietary supplements.

Seed dormancy is a key ecological attribute influencing germination timing and the ability of species to establish in variable environments. This study investigated whether inter-population variability in seed dormancy expression exists in Lonicera etrusca, a Mediterranean shrub known for producing seeds with underdeveloped embryos and multiple dormancy types. Seeds were collected from four geographically and ecologically distinct populations in central Iberia and subjected to a series of germination experiments simulating natural seasonal temperature regimes, stratification treatments, and gibberellic acid application. Across all populations, seeds exhibited morphological dormancy (MD) and varying degrees of morphophysiological dormancy (MPD), including non-deep simple and deep complex types. Despite high intra-specific variability in dormancy expression, no significant differences were found among populations for germination patterns or embryo growth responses. This indicates that dormancy variability is an intrinsic, conserved feature of the species rather than a locally adaptive trait. The homogenization of germination strategies across populations may be facilitated by bird-mediated seed dispersal, promoting gene flow and limiting local selection. These findings support the hypothesis that dormancy polymorphism in L. etrusca reflects a flexible germination strategy that enhances colonization potential across heterogeneous Mediterranean environments, rather than an environmentally induced plastic response.