Occurrence of secondary metabolites in tepals of Asphodelus ramosus L.

Major processes contributing to subtleties of ephemeral flowers of Asphodelus ramosus are related to chemical constituents detected in tepals which expand during cold and wet seasons in the eastern Mediterranean. Luteolin, caffeic acid, chlorogenic, and p-hydroxy-benzoic acids are the main constituents, whereas νalkanes, ketones, and fatty acids appear in low amounts

Stomatal responses of Eucalyptus species to elevated CO2 concentration and drought stress

Five species of Eucalyptus (E. grandis, E. urophylla, E. camaldulensis, E. torelliana, and E. phaeotrica), among the ten species most commonly used in large scale plantations, were selected for studies on the effects of elevated CO2 concentration [CO2] and drought stress on stomatal responses of 2.5-month old seedlings. The first three species belong to the subgenus Smphyomyrtus, whereas the fourth species belongs to the subgenus Corymbia and E. phaeotrica is from the subgenus Monocalyptus. Seedlings were grown in four pairs of open-top chambers, arranged to have 2 plants of each species in each chamber, with four replications in each of two CO2 concentrations: 350 ± 30 mumol mol-1 and 700 ± 30 mumol mol-1. After 100 days in the chambers, a series of gas exchange measurements were made. Half the plants in each chamber, one plant per species per chamber, were drought-stressed by withholding irrigation, while the remaining plants continued to be watered daily. Drought stress decreased stomatal conductance, photosynthesis and transpiration rates in all the species. The effect of drought stress on stomatal closure was similar in both [CO2]. The positive effects of elevated [CO2] on photosynthesis and water use efficiency were maintained longer during the stress period than under well-watered conditions. The photosynthetic rate of E. phaeotrica was higher even in the fourth day of the drought stress. Drought stress increased photoinhibition of photosynthesis, as measured by chlorophyll fluorescence, which varied among the species, as well as in relation to [CO2]. The results are in agreement with observed differences in stomatal responses between some eucalyptus species of the subgenera Symphyomyrtus and Monocalyptus

Aspects of cell wall extensibility in Ceratonia siliqua L.

The extensibility of isolated cell walls of young expanding leaves and root apices from Ceratonia siliqua L. (carob tree) has been investigated when: a) subjected to acidic buffers, b) treated with enzymes degrading specific cell wall components and c) applied crude protein extract from growing walls of cucumber and carob. The extension was generally restricted and smaller than that reported for rapidly growing tissues; while, specimens treated with pectolyase and pectinase rapidly extend

Physiological Responses of Capparis spinosa L. to Drought

This paper describes leaf growth, root distribution and water relations of the wild species Capparis spinosa L. during a 25 day soil-drying treatment. Leaf and root growth were unaffected by water deficit; nevertheless, root growth during soil drying was largely due to osmotic adjustment, which increased with depth. Analysis of the water relations of young expanding and fully expanded leaves demonstrated that ψ and ψp could not be used as indicators for Capparis response to drought. Stomata closed before zero turgor was reached. Therefore, factors other than turgor control leaf production and growth. Cell wall properties, mainly cell wall plasticity, might be associated with extensibility of the tissue and consequently with dry matter production under drought conditions. In conclusion, the salient features of the growth mechanism of Capparis demonstrate a sophisticated plant response to drought, involving osmotic adjustment, regulated stomatal opening, cell wall properties and increased root density. © 1990, Gustav Fischer Verlag, Stuttgart. All rights reserved

Changing mediterranean environment: Irrefutable evidence from pre-industrial, unpublicised scenes contemporary with a mission (1786-1787) in the levant

This paper provides an introduction to one hundred thirty one, pre-industrial, unpublicised Mediterranean scenes kept in Oxford, which constitute valuable evidence of changing environment. The largely unknown and unpublished paintings witness environmental wilderness and the cultural landscapes of the region, late in the 18th century. They depict sixty two scenes from Greece, forty two from Turkey, twenty two from Italy, three from Cyprus and two from Gibraltar. The paintings reveal changes that have occurred over the last two centuries in Mediterranean ecosystems; uninhabited areas, mountainous expanses, coastal regions, and Aegean islands. The region belongs to the hotspots of the biodiversity on Earth. Scientific interest in archival material has been revived, on account of research into a diversity threatened by anthropogenic activities and climate change. In this context, unknown Mediterranean scenes of 18th century offer another perspective on this complex subject of enquiry, they support efforts towards protection and preservation of natural environment and heighten interest in the management of diverse Mediterranean ecosystems. © 2012 Global NEST

Is negative turgor fallacious?

In early studies, negative turgor pressure was obtained by indirect methods and was mainly related to inaccurate measurements of osmotic and/or water potential. The uncertainties in the measurements made any discussion of the underlying reasons and phenomena premature and risky, perhaps even useless. Yet, the idea of relating negative turgor to the strength of small-sized cells with thick walls, to resist collapse when subjected to water deficit, seemed attractive. Negative turgor pressures are difficult to detect in higher plants, but they are theoretically possible. Regarding their origin, a hypothesis is discussed here, that the negative turgor detected in leaves might indicate a reversal of the water flow that has occurred in roots, under conditions of severe and prolonged drought

Symbolic plant(s) of the Olympic Games

The victors of the Olympic Games in ancient Greece were awarded crowns made of olive branches. In Antiquity, the symbolism of plants was related to myths, properties, aesthetic values, and civilization. Theophrastus first classifies and identifies plants, and gathers information about them, in his classic books (4th century BC). Symbolic plants are native to the Mediterranean region and they exhibit some convergent behaviour with respect to their functional characteristics. These plants were collected (among other species) by Professor J. Sibthorp and his partners in two botanical journeys in the Levant during the 18th century, and they have been illustrated for Flora Graeca Sibthorpiana