We used two sunflower genotypes displaying pericarp-imposed dormancy at high incubation temperatures (i.e. 30°C) to investigate the role of the pericarp as a limitation to oxygen availability to the embryo (hypoxia), and its impact on embryo abscisic acid (ABA) content and sensitivity to ABA. Results showed that both genotypes displayed very different oxygen threshold values for inhibition of embryo germination when incubation was performed at 30°C. Expression of dormancy in one genotype was therefore related to exacerbated embryo sensitivity to hypoxia, whereas in the other genotype, the pericarp appeared to act as a more severe restraint to oxygen entry. Increased sensitivity to hypoxia was, in part, related to increased sensitivity to ABA, but not to alterations in ABA metabolism. The activity of pericarp-microbial communities (bacteria and fungi) at high temperatures was also assessed as a potential determinant of hypoxia to the embryo. Oxygen consumption in pericarps incubated at 30°C was attenuated with antibiotics, which concomitantly promoted achene germination. In agreement with the observed more severe oxygen deprivation to the embryo exerted by the pericarp, the bacterial load in the pericarp was significantly higher in the commercial hybrid than in the inbred line; however, the application of antibiotics strongly reduced the bacterial colony counts for each genotype. Different bacterial and fungal communities, assessed through their profiles of carbon-source utilization, were determined between genotypes and after treatment with antibiotics. This work highlights the relationship between enhancement of sensitivity to hypoxia with incubation temperature and seed dormancy expression, and suggests that microbial activity might be part of the mechanism through which hypoxia is imposed.

Mayweed (Anthemis cotula L. # ANTCO) achenes and seed were germinated in the laboratory at constant temperatures ranging from 5 to 30 C. Maximum percent germination occurred at 20 C for both achenes and seed. Under all conditions tested, achene germination was less than seed germination. Both acid scarification for 15 min and soaking in 14 mM gibberellic acid (GA3) more than doubled achene germination. Pericarp leachate inhibited achene and seed germination only at high concentrations, indicating that inhibitors in the pericarp are not a primary cause of low germination in achenes. Optimum germination of achenes and seed occurred at pH 4.5 and over a range from pH 3 to pH 6. Achene germination was inhibited to a greater degree by moisture stress than was seed germination. It appears that structural integrity of the pericarp is the predominant factor affecting mayweed germination.

The anatomy of the husk (lemma and palea) and caryopsis coat (pericarp, seed coat or testa, and nucellar epidermis) of a typical mature wild oat (Avena fatua L.) caryopsis was investigated using both scanning electron microscopy and light microscopy. Both the lemma and palea consist of very thick-walled, lignified cells. In section, the lemma appears almost twice as thick as the palea. The pericarp is comprised of only one or two layers of relatively thin-walled cells and is closely appressed to the underlying seed coat over most of the grain. Both the outer seed-coat cuticle and the inner cuticle are present over almost the entire caryopsis and are continuous with the pigment strand that occurs deep in the crease region of the grain. The only discontinuities in the seed coat are at the basal end of the grain near the embryo. In the dorsal region of the caryopsis, the outer cuticle is approximately 3.5 μm in thickness, whereas the inner cuticle is less than 1 μm in thickness. Where the two pass over the embryo they are much thinner, with the inner cuticle becoming almost indistinguishable in places. The remains of the nucellar epidermis are tightly amalgamated to the seed coat and outer tangential walls of the underlying aleurone cells, which are clearly distinguishable by their large size and characteristic appearance.

Anatomical and morphological seed traits are of great ecological importance and are a main subject of, for example, seed bank or endozoochory studies. However, we observed a lack of information about the relationship between seed anatomy and seed morphology and its ecological implications. To fill this gap, we linked the anatomical features of diaspore coverings to morphological characteristics of free seeds and one-seeded fruits. We predicted that: (1) the thickness and anatomical complexity of seed coat and pericarp are related to diaspore size and shape; and (2) the presence or absence of the pericarp may influence seed-coat thickness and anatomy. In our study we investigated diaspores of 39 central-eastern European herbaceous species and recorded the thickness and anatomical complexity of their seed coverings, and we determined diaspore mass and shape. Our results indicate that diaspore mass is positively related to covering thickness, lignification degree and anatomical complexity. This might be the case because bigger diaspores tend to remain on the soil surface and are more exposed to predation risk and environmental threat than smaller diaspores. Furthermore, more round-shaped diaspores had disproportionately thicker and more lignified coverings than long or flat ones, probably because round-shaped diaspores much more frequently form seed banks and therefore persist for a long time in the soil. We also found that free seeds as diaspores have a thicker and more lignified seed coat than seeds enclosed in fruits. In one-seeded fruits, the pericarp ‘takes the protective role’, it is thick, and the seed coat is poorly developed.

The dispersal unit of many species of Brassicaceae is an indehiscent fruit, but relatively few studies have tested the effect of the pericarp on seed germination in this family. Our aim was to determine the effect of the pericarp on seed dormancy in six species of Brassicaceae native to the cold desert of north-west China. Intact dispersal units and isolated seeds of Chorispora sibirica, Euclidium syriacum, Goldbachia laevigata, Spirorrhynchus sabulosus, Sterigmostemum fuhaiense and Tauscheria lasiocarpa were stored dry at ambient laboratory conditions for 0–12 months and tested for germination in light and in dark at 5/2, 15/2 and 30/15°C. The amount of water absorbed by fruits and by seeds within the fruits was determined. For four species, intact fruits, isolated seeds and isolated seeds plus the removed pericarps were used to test for the mechanical versus possible chemical role of the pericarp in seed dormancy. Fresh isolated seeds, which have a fully developed embryo, germinated to lower percentages and rates than afterripened seeds. Thus, seeds have non-deep physiological dormancy. The pericarp significantly reduced germination, but inhibition was not due to lack of water uptake by seeds or to chemical inhibitors. Afterripened seeds of the six species germinated to 0–50% inside the fruits. We conclude that the pericarp plays a dominant role in seed dormancy of the six study species, and it does so by mechanically restricting embryo growth. Thus, the pericarp has the potential to spread germination over an extended period of time.

Introduction. Mangosteen (Garcinia mangostana) is a tropical fruit that isfamous for its edible pulp. This edible pulp makes up only 30% of the total fruit, whilethe remaining pericarp and seed are regarded as waste. Facing the increasing public demandfor naturally safe foods and products, our study aimed to elucidate the antioxidantcapacity and antibacterial activity of different parts of mangosteen, including thepericarp, pulp and seed. Materials and methods. The antioxidant capacities ofmangosteen’s pericarp, pulp and seed extracts were determined using the ferric reducingantioxidant power (FRAP) assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, whereasantibacterial activity was determined using the disc diffusion method.Results. The pericarp extract exhibited higher antioxidant capacities thanthose of pulp and seed extracts, with a Trolox equivalent antioxidant capacity (TEAC)value of 122.00 µM·g–1 and ferrous sulphate equivalent antioxidant capacity (FEAC) valueof 18.99 mM·g–1. All mangosteen extracts showed strong inhibition against Staphylococcus aureus ATCC11632, while only the pericarp extract was effectiveagainst Bacillus cereus ATCC10876. No inhibition againstEscherichia coli ATCC10536 was observed. Conclusion. Theoutcomes of our study could facilitate future application of mangosteen waste as abiopreservative in the food industry.

The interaction between ethylene production and seed germination of sugar beet (Beta vulgaris L.) was studied. For intact fruits, deoperculated fruits and true seeds, ethylene was only produced after the start of radicle emergence. Removal of the operculum or the whole pericarp, likely allowing better water uptake and gas exchange by the true seed, actually increased the time span between the start of radicle emergence and the beginning of ethylene production compared to intact fruits. ACC (1-aminocyclopropane-1-carboxylic acid), AOA (aminooxyacetic acid), AIB (2-amino isobutyric acid) and STS (silver thiosulphate) in the imbibition medium did not influence the germination pattern. Based on these findings, the function of ethylene during the germination of sugar beet is uncertain.

Pouzolzia rugulosa (Wedd.) Acharya & Kravtsova, comb. nov., is transferred from the genus Boehmeria on the grounds of the anatomy and morphology of the fruit, correlated with molecular data. A revised set of anatomical and morphological characters is provided to distinguish between Boehmeria and Pouzolzia. Pouzolzia rugulosa shares morphological similarities with a group of serrate-leaved taxa in that genus known from Asia and Oceania. It is a shrub or small tree and is found along the southern slopes of the Himalayas from Himachal Pradesh in northern India to the mountains of northern Burma. It occurs in forest at elevations of up to 1900 m, mainly at forest edges and in clearings. A full description of Pouzolzia rugulosa, including drawings and SEM images of the fruit, is provided, together with a key.

Introduction. After harvest, litchi fruits (Litchi chinensis Sonn.) rapidly lose their bright red skin color. Peel browning of harvested litchi fruit has largely been attributed to rapid degradation of red anthocyanin pigments associated with the oxidation of phenolic compounds by polyphenol oxidase (PPO) and/or peroxidase (POD). An anthocyanase has been also identified in litchi peel. Our work aimed at characterizing two specific litchi varieties that differ greatly in their color and browning behavior. Materials and methods. The anthocyanins, polyphenol oxidase (PPO), peroxidase (POD) and anthocyanase in the pericarp of two litchi cultivars, Kwai May and Wai Chee, grown in Reunion Island and Spain, respectively, were studied. Results and discussion. The qualitative composition of major anthocyanins (cyanidin-3-rutinoside and cyanidin-3-glucoside) was identical for the two cultivars studied, but, quantitatively, the variety Kwai May had a lower concentration than Wai Chee (64% less) of cyanidin-3-rutinoside. This component represented more than 90% of total anthocyanins in both cultivars. The activity of PPO was 6 times greater in the variety Kwai May than in Wai Chee and the activity of POD 30 times greater. The activity of POD was greater than that of PPO in both varieties. These differences help to explain the different behaviors of the cultivars during subsequent postharvest studies.

Introduction. The litchi tree produces fruit in terminal panicles in a development cycle of approximately 4 months. Data on its morphology and anatomy are scarce, although the fruit is of fundamental importance in the Sapindaceae systematic. This work was carried out to study fruit morphology and pericarp anatomy during the development of the cv. Brewster litchi. Materials and methods. Fruits were collected at different development phases on 12-year-old trees. The fruits were morphologically and anatomically studied. After fixation, the samples were sectioned in several anatomical planes, and mounted in temporary or permanent preparations. Results. The flowers were functionally male and female, with a superior bicarpelar ovary with two ovules, rarely three. Frequently, only a single fruit develops. The fruit is a heart-shaped drupe when ripe, fleshy and indehiscent. The pericarp is thin, leathery, rough, wrinkled and red colored, with aril covering all the seed. The fruit begins differentiation with the formation of the pericarp which consists of epicarp, mesocarp and endocarp. Discussion. The litchi fruit is elongated when young, becoming heart-shaped as it develops. It contains one or two seeds and each one is attached to the internal angle of the marginal sutures. When ripe, the litchi has a leathery and broken pericarp because of the presence of brachisclereides immediately below the epidermis, whose function may be protection against mechanical and physiological stresses and herbivorous action.

Bulbostylis somaliensis Lye (Cyperaceae) is described from Somalia. It is closely related to B. hispidula (Vahl) R. Haines, but differs in its smaller achenes as well as in the shape and surface structure of the achenes. The major diagnostic characters are the non-triangular achene and the outermost cells to the pericarp, which have several papillae in each cell. Three subspecies are distinguished, viz. subsp. somaliensis, subsp. confusa Lye and subsp. microcarpa (Chiov.) Lye.

Anatomical features of cowpea (Vigna unguiculata) associated with stem and pod wall resistance to the legume pod borer, Manica testulalis, were studied. The anatomical microenvironment of the area immediately post the stem epidermis seems to impose severe limitation to larval movement and feeding within the tissue. Collenchyma cells in both 21-day old TVu 946 and IT82D-716 stems form a network of closely knit interlocking cells with a few intercellular spaces. Significant differences (P < 0.05) were observed in the distance between the epidermis and collenchyma cells of the slightly raised (convex) and concave portions of TVu 946 and IT82D-716 stems. TVu 946 had a smaller stem diameter than IT82D-716 stem. Distance between epicarp and mesocarp tissues of 7-day old TVu 946 and IT82D-716 pod wall did not show any significant difference. Similarity in cell and tissue arrangement and the absence of strengthening tissues in pod wall could be some of the most important constraints responsible for their vulnerability to larval damage.

Stem anatomy is considered to be an important factor in stem resistance to M. testulalis, but this does not appear to be the case in pod wall resistance.