Floral visitors, their frequency, activity rate and Index of Visitation Rate in the strawberry fields of Ribatejo, Portugal : selection of potential pollinators : Part 1

Copyright © 2009 Universita degli Studi di Firenze.This study was carried out in one of the most important strawberry (Fragaria × ananassa Duch.) producing regions of Portugal, the Ribatejo, and aims to describe the quantitative component of visits by strawberry floral visitors under open field conditions. The main objectives were: (1) to assess the flower-visiting insects of the strawberry crop; (2) to evaluate the percentage of frequency (F) and activity rate (AR) in order to determine an Index of Visitation Rate (IVR) for the different categories of visitors. This study allowed us to access the vast spectrum of flower-visiting insects of the strawberry crop and to characterize their visits regarding parameters such as F and AR, used to calculate IVR. Based on the referred index it was possible to highlight three categories of insect visitors: Syrphidae (Diptera), Apis mellifera L. (Hymenoptera) and native bees (Hymenoptera). Other aspects were evaluated such as no. ind/flower throughout three different phases of the blooming period and field conditions. All the parameters allowed us to gather a set of information inherent to each of these categories, which will be useful for conservation and management procedures aiming at adequate pollination of the strawberry crop

Epiphytes modulate Posidonia oceanica photosynthetic production, energetic balance, antioxidant mechanisms, and oxidative damage

Epiphytes impose physical barriers to light penetration into seagrass leaves causing shading, which may decrease the production of reactive oxygen species (ROS), but also constitute a physical aggression that may trigger the production of ROS, leading to oxidative damage. Here we investigate the effects of epiphytes on Posidonia oceanica under both interactive perspectives, light attenuation and oxidative stress. Specifically the role of epiphytes in net photosynthesis, chlorophyll a and b, photoprotection (Violaxanthin+Anteraxanthin+Zeaxanthin cycle), soluble sugar and starch contents, enzymatic [ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR)] and global [trolox equivalent antioxidant capacity (TEAC)] and [oxygen radical antioxidant capacity (ORAC)] antioxidant responses, phenolics and oxidative damage (malondialdehyde) are tested. Leaves with epiphytes showed higher chlorophyll b and lower content in VAZ cycle carotenoids. Epiphyte shading was the probable reason for the lower VAZ de-epoxidation-ratio of leaves with epiphytes. In spite of being shaded, leaves with epiphytes showed higher antioxidant levels, indicating that epiphytes trigger the production of ROS. Both ORAC and TEAC and also APX and DHAR activities were higher in leaves with epiphytes, indicating that this response was related with its presence. Malondialdehyde concentrations also suggest oxidative damage caused by epiphytes. We conclude that the epiphyte load causes oxidative stress in P. oceanica and the mechanisms to scavenge ROS were not completely effective to avoid cell damage

Antioxidant, Anti-5-lipoxygenase and Antiacetylcholinesterase Activities of Essential Oils and Decoction Waters of Some Aromatic Plants

The scavenging of free radicals and superoxide anion, the inhibition of 5-lipoxygenase and the antiacetylcholinesterase activities of essential oils and decoction waters of eight aromatic plants (Dittrichia viscosa, Foeniculum vulgare, Origanum vulgare, Salvia officinalis, Thymbra capitata, Thymus camphoratus, Thymus carnosus and Thymus mastichina) were studied. The essential oils were dominated by 1,8-cineole in S. officinalis (59%), T. mastichina (49%) and T. camphoratus (21%); borneol (20%) in T. carnosus; carvacrol in Thymbra capitata (68%); gamma-terpinene (49%) in O. vulgare; alpha-pinene (26%) in F. vulgare; and trans-nerolidol (8%) + beta-oplopenone (7%) in D. viscosa. O. vulgare decoction waters had the highest amount of phenols (45 +/- 3mg GAE/mL) while F. vulgare only had 5 +/- 0mg GAE/mL. The decoction waters showed higher radical scavenging activity than the essential oils. O. vulgare decoction water showed the best antioxidant activity (IC(50) = 3 +/- 0 mu g/mL), while the most effective essential oils were those of Thymbra capitata (IC(50) = 61 +/- 2 mu g/mL) and O. vulgare (IC(50) = 156 +/- 5 mu g/mL). Thymbra capitata (IC(50) = 6 +/- 0 mu g/mL) decoction water showed the best superoxide anion scavenging activity. F. vulgare decoction water and essential oil revealed the best 5-lipoxygenase inhibition capacity (IC(50) = 27 +/- 1 mu g/mL and IC(50) = 68 +/- 2 mu/mL, respectively). T. mastichina (IC(50) = 46 +/- 4 mu g/mL), S. officinalis (IC(50) = 51 +/- 4 mu g/mL), Thymbra capitata (IC(50) = 52 +/- 1 mu g/mL) and T. camphoratus (IC(50) = 137 +/- 2 mu g/mL) essential oils showed the best antiacetylcholinesterase activity

Comparative analysis of the relative importance of different pollinating agents on strawberry crop

V Congresso Ibérico de Ciências Hortícolas, Porto, Maio 2005.A maioria das cultivares modernas de morangueiro possuem flores hermafroditas auto-férteis cuja polinização está dependente da acção combinada de vários agentes, nomeadamente o vento, a gravidade e os insectos polinizadores. A contribuição relativa de cada um destes agentes de polinização é variável consoante as cultivares envolvidas e o ambiente em que está inserida a cultura (estufai ar-livre). Com o objectivo de avaliar a importância dos vários agentes de polinização, na cultivar Camarosa, em condições de ar-livre, foram introduzidas várias colmeias num campo localizado na região do Ribatejo (Almeirim), no início da floração do ano de 2004. A metodologia utilizada consistiu na realização de experiências de polinização controlada a flores primárias da cultura, tendo sido definidos um total de seis modalidades: 1- Flores não embolsadas (Controlo); 2- Flores emasculadas, não embolsadas; 3- Flores embolsadas em tule; 4- Flores emasculadas, embolsadas em tule; 5- Flores embolsadas em celofane; 6- Flores polinizadas manualmente, embolsadas em celofane. Para cada modalidade foram analisados os seguintes parâmetros: peso e dimensões (diâmetros e altura) dos frutos, percentagem de vingamento e percentagem de frutos deformados. As modalidades com flores expostas às visitas dos insectos originaram frutos de maior peso e maiores dimensões e menor percentagem de frutos deformados. Em relação ao vento, os resultados apontam para a sua relevância, sobretudo na promoção da auto-polinização na flor do morangueiro.ABSTRACT: Most modem strawberry cultivars bear hermaphroditic flowers and are self fertile and their pollination can be achieved by three complementary agents, namely wind, gravity and insects. The relative contribution of each pollinating agent can be influenced by the adopted cultivar and by the conditions surrounding the crop (greenhouse/open-field). To evaluate the relative contribution of these agents on strawberry Camarosa cultivar, when the flowering period of 2004 began, some beehives were introduced in a field located in Ribatejo (Almeirim). The methodology adopted consisted on a controlled pollination experiment where six treatments were defined: I) Free pollinated flowers (Control); 2) Emasculate flowers, free pollinated; 3) Flowers caged in tulle; 4) Emasculate flowers, caged in tulle; 5) Flowers caged in cellophane; 6) Hand pollinated flowers caged in cellophane. For each treatment the following parameters were analysed: weight size (two diameters and height), percentage of malformed fruits and fruit set. The uncaged flowers treatments had the heaviest and the biggest fruits, as well as the lowest percentage of malformed fruits. In what concerns the wind the results reveal its importance, mainly on the self-pollination improvement of the strawberry flowers

Effects of in situ shading on the photophysiology of Zostera marina and Cymodocea nodosa

The effects of light reduction were investigated in natural stands of the seagrasses Zostera marina and Cymodocea nodosa in Ria Formosa coastal lagoon, southern Portugal. Four shading plots and a control were set in each of two neighbouring meadows (2-3 m depth), each dominated by one species. The experiment lasted for 3 weeks, at the end of which the response of plant photosynthesis to light was determined via oxygen electrode measurements. Tissue samples were also analysed for photosynthetic pigment, soluble protein, soluble sugar and malondialdehyde contents. All plants presented a shade-adapted profile, mostly revealed by their biochemical composition. In both species the chlorophyll a/chlorophyll b ratio decreased sharply whereas the total chlorophyll/total carotenoids and the total chlorophyll/soluble protein ratios increased. Soluble protein content was reduced more noticeably in Z. marina. Soluble sugars dropped almost 40% in Z. marina leaves and roots, a more pronounced effect than the one observed in C. nodosa. Overall, Z. marina revealed to be more sensitive than C. nodosa to reductions in incident irradiance, suggesting that it will be more sensitive to human-induced disturbances that result in an increase of water turbidity

Ecological niches in the polyploid complex Linum suffruticosum s.l.

IntroductionThe high frequency of polyploidy in the evolutionary history of many plant groups occurring in the Mediterranean region is likely a consequence of its dynamic paleogeographic and climatic history. Polyploids frequently have distinct characteristics that allow them to overcome the minority cytotype exclusion. Such traits may enable polyploid individuals to grow in habitats different from their parentals and/or expand to new areas, leading to spatial segregation. Therefore, the successful establishment of polyploid lineages has long been associated with niche divergence or niche partitioning and the ability of polyploids to cope with different, often more stressful, conditions. In this study, we aimed to explore the role of environmental variables associated with the current distribution patterns of cytotypes within the polyploid complex Linum suffruticosum s.l..MethodsThe distribution and environmental niches of the five main cytotypes of Linum suffruticosum s.l. (diploids, tetraploids, hexaploids, octoploids and decaploids) were studied across its distribution range. Realized environmental niche of each cytotype was determined using niche modelling tools, such as maximum entropy modelling and niche equivalency and similarity tests. ResultsDifferences in the environmental conditions of L. suffruticosum s.l. cytotypes were observed, with polyploids being associated with habitats of increased drought and soil pH, narrower temperature ranges and decreased soil water and cation exchange capacities. Diploids present the widest environmental niche, and polyploids occupy part of the diploid niche. Although some polyploids have equivalent potential ecological niches, cytotypes do not co-occur in nature. Additionally, the ecological niche of this polyploid complex is different between continents, with North African habitats being characterised by differences in soil texture, higher pH, and low cation exchange capacity, precipitation and soil water capacity and higher temperatures than habitats in southwest Europe. DiscussionThe different ecological conditions played a role in the distribution of cytotypes, but the mosaic distribution could not be entirely explained by the environmental variables included in this study. Other factors, such as reproductive isolation and competitive interactions among cytotypes, could further explain the current diversity and distribution patterns in white flax. This study provides relevant data on the niche requirements of each cytotype for further competition and reciprocal transplant experiments. further competition and reciprocal transplant experiments

Responses of zostera marina and cymodocea nodosa to light-limitation stress

The effects of light-limitation stress were investigated in natural stands of the seagrasses Zostera marina and Cymodocea nodosa in Ria Formosa coastal lagoon, southern Portugal. Three levels of light attenuation were imposed for 3 weeks in two adjacent meadows (2–3 m depth), each dominated by one species. The response of photosynthesis to light was determined with oxygen electrodes. Chlorophylls and carotenoids were determined by high-pressure liquid chromatography (HPLC). Soluble protein, carbohydrates, malondialdehyde and phenol contents were also analysed. Both species showed evident signs of photoacclimation. Their maximum photosynthetic rates were significantly reduced with shading. Ratios between specific light harvesting carotenoids and the epoxidation state of xanthophyll cycle carotenoids revealed significantly higher light harvesting efficiency of C. nodosa, a competitive advantage in a low light environment. The contents of both soluble sugars and starch were considerably lower in Z. marina plants, particularly in the rhizomes, decreasing even further with shading. The different carbohydrate energy storage strategies found between the two species clearly favour C. nodosa's resilience to light deprivation, a condition enhanced by its intrinsic arrangement of the pigment pool. On the other hand, Z. marina revealed a lower tolerance to light reduction, mostly due to a less plastic arrangement of the pigment pool and lower carbohydrate storage. Our findings indicate that Z. marina is close to a light-mediated ecophysiological threshold in Ria Formosa

Engolo and Capoeira. From Ethnic to Diasporic Combat Games in the Southern Atlantic

This article provides a re-examination of the main Afrocentric narrative of capoeira origins, the engolo or ‘Zebra Dance’, in light of historical primary sources and new ethnographic evidence gathered during fieldwork in south-west Angola. By examining engolo’s bodily techniques, its socio-historical context and cultural meanings, the piece emphasises its insertion into a pastoral lifestyle and highlights the relatively narrow ethnic character of the practice in Angola. This analysis and the comparison with capoeira helps us to develop certain hypotheses about the formation, migration, and re-invention of diasporic combat games between southern Angola and coastal Brazil, and more broadly, to increase our understanding of how African cultures spread across the southern Atlantic