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... To extract independently the epicuticular and intracuticular waxes of the adaxial and abaxial surfaces of a C. siliqua leaflet, the mechanical (cryo-adhesion) method proposed by Ensikat et al. 10 was adopted here for the first time, unlike previous authors who used the classical chloroform-based extraction method. 33,34 The cryo-adhesion method has several advantages: (1) the crystal structure and shape of the waxes are preserved; (2) the two types of cuticular waxes may be selectively isolated; and (3) insoluble or slowly soluble components, which might be lost in the classical solvent extraction method, may be extracted. Twenty fresh leaflet samples of approximately 3 × 2 cm 2 were gently cut with scissors. ...
... The static water CA values of the adaxial and abaxial surfaces of a C. siliqua leaflet are represented in Figure 6. These data demonstrate that the adaxial surface is hydrophobic, with CA values ranging from 80 ± 3 to 109 ± 4°( Figure 6, pink symbols), whereas the abaxial surface exhibits a superhydrophobic behavior, with CA values ranging from 143 ± 4 to 162 ± 3°( Figure 6, orange symbols), which are higher than those obtained by Kolyva et al. 34 We attribute this difference to the optimized procedure adopted in the present work (cf. details in the Experimental Section). ...
... We note that the replication of the surfaces of the C. siliqua leaflet was never attempted before. Kolyva et al. 34 produced solely negative and positive replicas of the waxless (treated) adaxial and abaxial surfaces. Two pieces of evidence demonstrate that the replication of the abaxial surface of a natural (untreated) C. siliqua leaflet is the most suitable, on account of the synergic effect existing between roughness and chemistry. ...
The production of superhydrophobic coatings inspired by the surface of plant leaves is a challenging goal. Such coatings hold a bright technological future in niche markets of the aeronautical, space, naval, building, automobile, and biomedical sectors. This work is focused on the adaxial (top) and abaxial (bottom) surfaces of the leaflet of the Ceratonia silique L. (carob), a high-commercial-value Mediterranean tree cultivated in many regions of the world. The adaxial and abaxial surfaces feature hydrophobic and superhydrophobic behaviors, respectively. Their chemical composition is very simple: monopalmitin ester and palmitic acid are protuberant in the epicuticular and intracuticular wax layers of the adaxial surface, respectively, whereas 1-octacosanol dominates in the abaxial wax layers. In both surfaces, epicuticular wax is organized along a randomly oriented and intricate network of nanometer-thick and micrometer-long plates, whose density and degree of interconnection are significantly higher in the abaxial surface. The measured tilting angles for the abaxial surface (12-70°) reveal unusual variable density and water adhesion of the nanostructured plate-based texture. Optical measurements demonstrate that light reflectance/absorbance of the glaucous abaxial surface is significantly higher/lower than that of the nonglaucous adaxial surface. In both surfaces, diffuse reflectance is dominant, and the absorbance is weakly dependent on the light incidence angle. We show that the highly dense nanostructured platelike texture of the epicuticular abaxial layer of the C. siliqua leaflet works as a sophisticated light and water management system: it reflects solar radiation diffusely to lower the surface temperature, and it has superhydrophobic character to keep the surface dry. Such attributes enable efficient gas exchange (photosynthesis and respiration), transpiration, and evaporation. To mimic for the first time the abaxial surface, a templation approach was adopted using poly(dimethylsiloxane) (PDMS)/poly(methylphenylsiloxane) (PMPS) positive/negative replicas and a soft polymer/siloxane negative replica produced by the sol-gel process. Because high topographical variations of the biotemplate and wax adhesion to the biohybrid film affected the replication quality, the reproduction of the wax texture via the synthesis of 1-octacosanol-grafted siloxane-based hybrid materials is proposed as a suitable route to duplicate the abaxial surface with high fidelity. The natural chemical/physical strategy adopted by the C. siliqua leaflet to face the harsh Mediterranean climate is a powerful source of bioinspiration for the development of diffuse reflecting and superhydrophobic material systems with foreseen applications as dual-functional antiglare and water-repelling coatings.
... The objective of this work was to study and compare leaf surface morphology and wettability of Arbutus unedo L. and Arbutus andrachne L., as well as the fatty acid composition of leaf lipids, as part of a larger study of leaf wettability of Mediterraenan plants (Kolyva et al. 2012;Fernández et al. 2014;Razeq et al. 2014). Arbutus unedo L. and A. andrachne L. belong to the Ericaceae family, and are relatively widespread in the Mediterranean region (Hileman, Vasey, and Parker 2001;Baslar, Dogan, and Mert 2002;Blondel et al. 2010). ...
... Wax extraction Cuticular layer and epicuticular waxes of fully expanded leaves of A. andrachne and A. unedo were removed by dipping the tissues in chloroform for 15-20 min (Buschhaus, Herz, and Jetter 2007a;Kolyva et al. 2012), at room temperature while being gently agitated. Microscopic examination of leaf surfaces was used to confirm removal of the wax. ...
... This different composition may partly contribute to the respective surface properties of the leaves of the two species (Buschhaus, Herz, and Jetter 2007b;Samuels, Kunst, and Jetter 2008;Domínguez et al. 2010;Declercq et al. 2014). It is worth noting that a CA > 90°indicates a hydrophobic surface, whereas a CA < 90°indicates a rather hydrophilic surface (Boyce and Berlyn 1988;Bhushan and Jung 2006;Kolyva et al. 2012). Hence, the elevated CA measured on the abaxial surface of A. andrachne may relate to the increased presence of surface wax microsculpturing on that surface compared with the rest of the examined leaf surfaces (Abas and Simoneit 1998). ...
Features of the adaxial and abaxial surface microstructure of Arbutus unedo L. and Arbutus andrachne L. are evaluated as possible consistent parameters contributing to the wetness of leaves. The abaxial leaf surface of A. andrachne and A. unedo was determined to be more hydrophobic than the adaxial leaf surface. Hydrophobicity may be of particular importance for the ecophysiological status of the hypostomatic leaves of both Arbutus species, which exhibit a long life span and are exposed to various environmental stimuli. Water
repellence may also be correlated to the increased presence of surface wax. Lipid analysis of the leaves of both plant species revealed an abundance of α-linolenic acid, with palmitic acid as the second major contributor, followed by linoleic and oleic acid. Oleic and linoleic acid were present in slightly larger percentages in A. andrachne compared to A. unedo, while myristic, palmitic and α-linolenic were found in elevated percentages in A. unedo. The fatty acid composition analysis of the leaf wax of A. andrachne and A. unedo ranged from C16 to C26, with fatty acids of an even longer chain length detected in the case of A. andrachne. Despite the similar fatty acid composition of total lipids, the composition of the wax fraction showed differences between the two Arbutus species, which may partly contribute to the foliar surface properties of the two species.
... Plants' adaptation to abiotic environmental stresses is associated with metabolic adjustments that lead to the accumulation of phenolics that ameliorate the damaging effects of abiotic stress . Additionally, substantial phenolic accumulation can occur in nitrogen-limited environments [20,65], which are actually the natural ecosystems of carob trees with their long-lived leaves [20,66], possessing an interesting functional leaf surface area . C. siliqua is a species that synthesizes and accumulates phenolics in the young stages of leaf development, as protective substances against biotic and abiotic stress factors . Thereafter, with the increment of leaf age (as well as leaf area and leaf mass) and maturation, the phenolic content of expanded leaves declines, which may be linked to the maintenance costs of these long-lived leaf tissues [26,51]. ...
Ceratonia siliqua L. (carob tree) is an endemic plant to the eastern Mediterranean region. In the present study, anatomical and physiological traits of successively grown compound leaves (i.e., the first, third, fifth and seventh leaves) of C. siliqua were investigated in an attempt to evaluate their growth under urban and suburban environmental conditions. Chlorophyll and phenolic content, as well as the specific leaf area of the compound leaves were determined. Structural traits of leaflets (i.e., thickness of palisade and spongy parenchyma, abaxial and adaxial epidermis, as well as abaxial and adaxial periclinal wall) were also investigated in expanding and fully expanded leaflets. Fully expanded leaflets from urban sites exhibited increased thickness of the lamina and the palisade parenchyma, while the thickness of the spongy parenchyma was thicker in suburban specimens. The palisade tissue was less extended than the spongy tissue in expanding leaflets, while the opposite held true for the expanded leaflets. Moreover, the thickness of the adaxial and the abaxial epidermises, as well as the adaxial and abaxial periclinal wall were higher in suburban leaflets. The chlorophyll content increased concomitantly with the specific leaf area (SLA) of both expanding and expanded leaflets, and strong positive correlations were detected, while the phenolic content declined with the increased SLA of expanding and expanded leaflets. It is noteworthy that the SLA of expanding leaflets in the suburban site was comparable to the SLA of expanded leaflets experiencing air pollution in urban sites; the size and the mass of leaf blades of C. siliqua possess adaptive features to air pollution. These results, linked to the functional structure of expanding and expanded successive foliar tissues, provide valuable assessment information coordinated with an adaptive process and yield of carob trees exposed to the considered ambient conditions, which have not hitherto been published.
... Plant ecophysiological or ecohydrographical arguments were suggested to explain the differences observed. Typically, the abaxial surface exhibits higher hydrophobicity (higher CA value) than the adaxial surface (Kolyva et al., 2012). In the leaf, the abaxial surface plays the role of water management system, keeping the surface dry through its superhydrophobic nature, while allowing essential processes to occur (photosynthesis, respiration, transpiration, and evaporation). ...
Classically, vicariant phenomena have been essentially identified on the basis of biogeographical and ecological data. Here we report unequivocal evidences that demonstrate that a physical-chemical characterization of the epicuticular waxes of the surface of plant leaves represents a very powerful strategy to get rich insight into vicariant events. We found the vicariant similarity between Cercis siliquastrum L. (family Fabaceae, subfamily Cercidoideae) and Ceratonia siliqua L. (family Fabaceae, subfamily Caesalpinoideae). Both taxa converge in the Mediterranean basin (C. siliquastrum on the north and C. siliqua across the south), in similar habitats (sclerophyll communities of maquis) and climatic profiles. These species are the current representation of their subfamilies in the Mediterranean basin, where they overlap. Because of this biogeographic and ecological similarity, the environmental pattern of both taxa was found to be very significant. The physical-chemical analysis performed on the epicuticular waxes of C. siliquastrum and C. siliqua leaves provided relevant data that confirm the functional proximity between them. A striking resemblance was found in the epicuticular waxes of the abaxial surfaces of C. siliquastrum and C. siliqua leaves in terms of the dominant chemical compounds (1-triacontanol (C30) and 1-octacosanol (C28), respectively), morphology (intricate network of randomly organized nanometer-thick and micrometer-long plates), wettability (superhydrophobic character, with water contact angle values of 167.5 ± 0.5˚ and 162 ± 3º, respectively), and optical properties (in both species the light reflectance/absorbance of the abaxial surface is significantly higher/lower than that of the adaxial surface, but the overall trend in reflectance is qualitatively similar). These results enable us to include for the first time C. siliqua in the vicariant process exhibited by C. canadensis L., C. griffithii L., and C. siliquastrum.
... The spray parameters are composed of the spray nozzle parameters (Negrisoli et al., 2019) and spray volume (Garcerá et al., 2020). The crop characteristics consist of surface characteristics (Kolyva et al., 2012;Massinon et al., 2017;Papierowska et al., 2019) and hydrophilicity (Wang et al., 2018;Zhou et al., 2018;Fang et al., 2019). ...
Droplet deposition behavior on pear leaf surfaces under wind-induced vibration was investigated.
The factors and limiting conditions affecting the vibration and spreading of droplets were analyzed.
A mathematical model of the vibration and spreading of droplets on pear leaves was constructed.
Abstract. Pear trees, a kind of fruit tree prone to diseases and insects, are sprayed 7-8 times a year in northern China and 8-10 times a year in the hot and humid areas of southern China. Air-assisted spraying is also the mainstream application technique for pear trees at present. To study the deposition behavior of droplets on pear leaves under the effect of air flow, the movement states of fluorescent droplets at different initial leaf angles and different leaf positions were measured with a high-speed camera. Based on the combined effect of the microstructure and the vibration of pear leaves, the factors and limiting conditions affecting the vibration and spreading of droplets were analyzed, and a mathematical model of the vibration and spreading of droplets on pear leaves was constructed. The experiment showed that the degree of influence of each factor on the velocity and acceleration of the droplets is in turn the inflow velocity, the drop position and the initial leaf angle. For pear hydrophilic plants, it is necessary to meet both conditions that the droplet velocity is less than the critical velocity of 1.1 m/s and the droplet acceleration is less than the critical acceleration of 20 m/s ² so that the droplet can deposit on the leaf surface. An inflow velocity of 7 m/s better facilitates droplet deposition and spreading. Keywords: Deposition behavior, Pear leaf, Wind-induced vibration.
... The objective of this work was to study and compare features of tepal and leaf surface micromorphology, wettability and fatty acid composition of A. ramosus grown in the field and exposed to rainfall, as part of a larger study of functional interfaces between plant tissues and environment, as well as adaptations of wild plants to environmental conditions Chimona et al., 2012;Kolyva et al., 2012;Gkikas et al., 2015;Koukos et al., 2015;Argiropoulos et al., 2017). Light-, scanning electron-and atomic force microscopy were used to study morphological traits of tepals and leaves of A. ramosus. ...
In this study functional micromorphological traits and water repellent attributes of floral and leaf surfaces of Asphodelus ramosus are presented. The branched inflorescences of A. ramosus bear numerous short-lived flowers arranged on tall flowering stalks, while the basal long-tapered leaves are long-lived. The most striking feature of the short-lived flowers of A. ramosus is the surface structure of the coloured midrib and the white bilateral sections of tepals, revealing different functionality between the two sections of tepals and the two sides of the corollas. Structural features of adaxial and abaxial epidermal cells may function predominantly for water repellence of floral tissues expanded during the humid period of the year. The leaves are more water repellent than the tepals and display declining water retention on their surfaces. It appears that micro- and nano-scale patterns observed on leaf and tepal surfaces of A. ramosus are linked to hydrophobic properties, which are important adaptive traits contributing to the seasonal performance of A. ramosus in the field, particularly in regard to water adhesion.
... The superficial examination indicated a marked difference in ultra-morphology of the two samples (in vitro and in vivo leaves), stomata were visible only on the abaxial surface in both the cases, while adaxial surfaces of in vivo leaves showed heavy depositions of epicuticular wax. An analogous outcome has also been obtained in SEM studies of carob leaves taken from mature trees (Kolyva et al. 2012). The effect of dehydration process (alcohol series and CPD) on in vitro leaves, among the two samples was more striking, while leaves harvested from in vivo conditions did not show any noteworthy effect of dehydration on the leaf surface characterization. ...
The article describes refined regeneration process in Ceratonia siliqua using different plant growth regulators along with antioxidant, SEM and IRGA analysis to understand the developmental behaviour of the plantlets.
The present study describes a simplified seed germination process in Ceratonia siliqua L. and gives a comparative analysis of hormonal supply for enhanced adventitious shoot regeneration through aseptic seedling-derived cotyledonary nodes. The axillary bud induction and multiplication was greatly influenced by the concentration and type of cytokinin viz. 6-benzylaminopurine (BA), meta-Topolin (mT), Kinetin (Kn) and Thiadiazuron (TDZ). Adenine-based cytokinins, BA and mT, augmented in Murashige and Skoog medium, were proved to be more responsive. The medium containing 10 µM BA produced a maximum of 9.1 ± 3.0 shoots/ explant. A combination of optimal concentration of BA with NAA (0.5 µM) however, resulted into a significant production of 28.10 ± 0.14 shoots per CN. Half-strength MS + IBA (10 µM) in the presence of light ensured more number of root formation while half-strength MS + IBA (5.0 µM) and stimulation in the dark for 1 week ensured better root growth (4.98 ± 0.08 cm). Plantlets were successfully acclimatized in soilrite™, showing 65% survival. The work is supported with the studies based on antioxidant enzyme activity as well as on net photosynthetic rate and its related attributes in comprehension with SEM analysis of leaves showing stomatal micromorphology during three stages: in vitro, during acclimatization and in net house conditions. The studies during acclimatization reflect better understanding of the stabilization of micropropagated plantlets to the environmental conditions.
... Ingente es la producción científica de investigadores de universidades europeas, americanas y suramericanas acerca de las evidencias paleobotánicas de las especie y de su presencia en la historia oral o escrita de los contextos geo-culturales a los que nos referimos. Recordamos a éste propósito los trabajos de Ramón-Laca y Mabberly (2004), LaMalfa et al. (2007), yFoteini et al. (2012). ...
This work aims to analyze the cultural history of the botanical species generally indicated as 'carob three', through the correlation between the Mediterranean carob (Ceratonia siliqua) and its South American relative (Prosopis pallida, affinis, chilensis o julinflora). Although the biological relationship between the two plants is thin, they share a combination of cultural and symbolic significances common to different communities in different geographical and cultural areas. In particular this paper, based on a field research in the Northern coast of Peru, will examine the symbolic characteristics of the South American carob three in the peculiar area of the Santuario Histórico Bosque de Pómac, in the region of Lambayeque.
... Σκοπός της εργαστηριακής άσκησης είναι η αποτύπωση και η εκτίμηση της παρουσίας των χρωστικών φυτικών ιστών και των εξωκυτταρικών δομών, δηλαδή του μικροαναγλύφου των άνω και κάτω επιφανειών φύλλων ή πετάλων των λουλουδιών με υδρόφοβες ιδιότητες, σύμφωνα με ιεραρχικά καθορισμένες δομές (Kolyva et al. 2012, Koukos et al. 2015. Η μελέτη των επιφανειών μπορεί να καθοδηγήσει την κατασκευή πρωτότυπων τεχνητών υλικών με επιθυμητές προδιαγραφές, το οποίο είναι και το ζητούμενο από τη σύγχρονη νανοτεχνολογία που αναζητά (διαρκώς) νέα υλικά (καινοτομίας). ...
... Σκοπός της εργαστηριακής άσκησης είναι η αποτύπωση και η εκτίμηση της παρουσίας των χρωστικών φυτικών ιστών και των εξωκυτταρικών δομών, δηλαδή του μικροαναγλύφου των άνω και κάτω επιφανειών φύλλων ή πετάλων των λουλουδιών με υδρόφοβες ιδιότητες, σύμφωνα με ιεραρχικά καθορισμένες δομές (Kolyva et al. 2012, Koukos et al. 2015. Η μελέτη των επιφανειών μπορεί να καθοδηγήσει την κατασκευή πρωτότυπων τεχνητών υλικών με επιθυμητές προδιαγραφές, το οποίο είναι και το ζητούμενο από τη σύγχρονη νανοτεχνολογία που αναζητά (διαρκώς) νέα υλικά (καινοτομίας). ...
Το Ηλεκτρονικό Σύγγραμμα με τον τίτλο Εργαστηριακές Ασκήσεις Φυσιολογίας Φυτών αναφέρεται σε «ερευνητικά αντικείμενα της Φυσιολογίας Φυτών και βοηθά φοιτήτριες και φοιτητές να γνωρίσουν τις λειτουργίες των φυτών και έτσι να καταλάβουν καλύτερα τα ακίνητα και σιωπηλά φυτά και να τα αγαπήσουν».
Το παρόν Ηλεκτρονικό Σύγγραμμα είναι αποτέλεσμα συλλογικού έργου όλων των συντελεστών (δηλαδή συγγραφέων, κριτικού αναγνώστη, καθώς και συντελεστών γλωσσικής και γραφιστικής επιμέλειας και τεχνικής επεξεργασίας).
Τα δεκατέσσερα κεφάλαια του Συγγράμματος καλύπτουν όλες τις θεμελιώδεις γνώσεις της Φυσιολογίας Φυτών και ορισμένες καινοτομίες της σύγχρονης επιστήμης των φυτών. Σε δύο παραρτήματα (Παράρτημα Ι και Παράρτημα ΙΙ) παρουσιάζεται αναλυτικά η προετοιμασία του φυτικού υλικού και των διαλυμάτων που είναι απαραίτητα για τη διεξαγωγή των εργαστηριακών ασκήσεων της Φυσιολογίας Φυτών.
ΚΕΦΑΛΑΙΟ 1. Η ανόργανη θρέψη των φυτών αφορά στη μελέτη της επίδρασης της έλλειψης θρεπτικών στοιχείων στην ανάπτυξη φυτών. Τα φυτά ως αυτότροφοι οργανισμοί, προσλαμβάνουν από το περιβάλλον όπου αναπτύσσονται τα απαραίτητα θρεπτικά στοιχεία για την ανάπτυξή τους.
ΚΕΦΑΛΑΙΟ 2. Απαραίτητη προϋπόθεση για τη φωτοσύνθεση των φυτών είναι η ύπαρξη των φωτοσυνθετικών χρωστικών των χλωροπλαστών. Σε αυτή την εργαστηριακή άσκηση διεξάγεται ο διαχωρισμός χρωστικών των πλαστιδίων και ο προσδιορισμός του φάσματος απορρόφησης των χρωστικών.
ΚΕΦΑΛΑΙΟ 3. Κατά τη φωτοσύνθεση προσλαμβάνεται φωτεινή ενέργεια από τις χρωστικές των πλαστιδίων και χρησιμοποιείται για την αναγωγή του CO2 της ατμόσφαιρας σε σάκχαρα. Σε αυτή την εργαστηριακή άσκηση πραγματοποιείται απομόνωση των χλωροπλαστών, διεξάγεται η μέτρηση της αναγωγικής ικανότητας των χλωροπλαστών (αντίδραση Hill) και υπολογίζεται η επίδραση της έντασης του φωτός στην αναγωγική ικανότητα των χλωροπλαστών.
ΚΕΦΑΛΑΙΟ 4. Κατά τη διεργασία της αναπνοής ανιχνεύονται οι περιοχές της αναπνευστικής δραστηριότητας φυτικών ιστών σε αρτίβλαστα φυτών.
ΚΕΦΑΛΑΙΟ 5. Ο μεταβολισμός του αζώτου σχετίζεται με τη μελέτη της υδρόλυσης των αποταμιευτικών πρωτεϊνών κατά την ανάπτυξη αρτιβλάστων. (Σημειώνεται πως την φύτρωση των σπερμάτων ακολουθεί η ανάπτυξη των αρτιβλάστων). Κατά τα πρώτα στάδια της ανάπτυξης των αρτιβλάστων, οι ανάγκες σε υποστρώματα και ενέργεια για τις έντονες αναβολικές διεργασίες των νεαρών φυτών εξασφαλίζονται από μια σημαντική ποσότητα αποταμιευτικών θρεπτικών ουσιών που περιέχονται στα σπέρματα. Οι ουσίες αυτές βρίσκονται στις κοτυληδόνες ή/και το ενδοσπέρμιο και τρέφουν το νεαρό φυτό μέχρι να αποκτήσει ανεπτυγμένο ριζικό σύστημα και φωτοσυνθετική ικανότητα.
ΚΕΦΑΛΑΙΟ 6. Το νερό αποτελεί τον σημαντικότερο περιβαλλοντικό παράγοντα για την αύξηση και ανάπτυξη των φυτών. Σε αυτή την εργαστηριακή άσκηση προσδιορίζεται το υδατικό δυναμικό σε κοτυληδόνες και υποκοτύλια αρτιβλάστων.
ΚΕΦΑΛΑΙΟ 7. Τα ανώτερα φυτά χρησιμοποιούν μόνο ένα πολύ μικρό ποσοστό του νερού που προσλαμβάνουν από το έδαφος, για τις διάφορες φυσιολογικές και βιοχημικές διεργασίες. Το υπόλοιπο διαχέεται στην ατμόσφαιρα με τη μορφή υδρατμών από τα υπέργεια όργανα των φυτών και κυρίως από τα στόματα των φύλλων. Το φαινόμενο αυτό ονομάζεται διαπνοή, και εξετάζεται στο εργαστήριο υπό την επίδραση διαφορετικών εξωτερικών παραγόντων που επηρεάζουν το τάχος της.
ΚΕΦΑΛΑΙΟ 8. Η παρουσία νερού, οξυγόνου και κατάλληλης θερμοκρασίας οδηγεί πολλά σπέρματα στη φύτρωση. Σε άλλα φυτικά είδη η παρουσία των παραγόντων αυτών δεν επαρκεί για τη φύτρωση, οπότε τα σπέρματα βρίσκονται σε μια κατάσταση που ορίζεται ως λήθαργος. Η μελέτη του φυτοχρωμικού ελέγχου της φύτρωσης και η άρση του λήθαργου από γιββερελλικό οξύ είναι το πειραματικό αντικείμενο αυτής της
άσκησης. Επίσης εξετάζεται ο ρόλος του σπερματικού περιβλήματος στην επιβολή λήθαργου.
ΚΕΦΑΛΑΙΟ 9. Το ορατό φως αντιστοιχεί στο τμήμα της ηλεκτρομαγνητικής ακτινοβολίας με μήκη κύματος από 380 nm (ιώδες) μέχρι 750 nm περίπου. Η απορρόφηση και η βιολογική δράση του φωτός προϋποθέτουν την παρουσία και τη διαμεσολάβηση ειδικών φωτοδεκτών, όπως το φυτόχρωμα (φωτομορφογένεση). Στην άσκηση αυτή εξετάζεται η δράση του φωτός στην ανάπτυξη αρτιβλάστων.
ΚΕΦΑΛΑΙΟ 10. Οι ουσίες που είναι ευρέως γνωστές ως φυτικές ορμόνες (plant hormones) ή φυτοορμόνες, ως φυτο-αυξητικές ουσίες (plant growth substances) ή φυτο-αυξητικοί ρυθμιστές (plant growth regulators) προωθούν ή αναστέλλουν την αύξηση των φυτών και μπορεί να είναι ενδογενείς ή/και συνθετικές.
ΚΕΦΑΛΑΙΟ 11. Με τον φωτοτροπισμό εξετάζεται η τάση που παρουσιάζουν τα φυτά να τρέπονται προς το φως (θετικός φωτοτροπισμός) ή να αποτρέπονται από το φως (αρνητικός φωτοτροπισμός).
ΚΕΦΑΛΑΙΟ 12. Η αναπόφευκτη γήρανση των φύλλων των φυτών συνοδεύεται από αποικοδόμηση των χλωροφυλλών και καταστροφή των χλωροπλαστών. Σε αυτή την εργαστηριακή άσκηση διεξάγεται ο διαχωρισμός των χρωστικών των πλαστιδίων και ο προσδιορισμός του φάσματος απορρόφησης των χρωστικών.
ΚΕΦΑΛΑΙΟ 13. Με το νέο επιστημονικό πεδίο της βιομιμητικής προωθείται η διεπιστημονική, ερευνητική προσέγγιση και πρόσφατα αποτελέσματα που προέρχονται από τα φυτά συμβάλλουν ήδη στην επίλυση σύγχρονων τεχνολογικών θεμάτων.
ΚΕΦΑΛΑΙΟ 14. Το φυτό Arabidopsis thaliana παρουσιάζεται ως οργανισμός-μοντέλο (το φυτό-μοντέλο) στη μοριακή και γενετική ανάλυση και αναφέρονται οι λόγοι για τους οποίους έχει επιλεγεί έναντι άλλων φυτών.
... Light perceived by plant tissues is an important variable, and the subsequent path of a light beam depends on the optical properties of the plant material . In the extensive literature on leaf physiology, the importance of light perception by leaf surfaces has been recognised as a major factor of modelling foliar development (Dicker et al., 2014;Gerber et al., 2011;Kolyva et al., 2012;Martin et al., 1989;McClendon, 1984;Vogelmann and Björn, 1986;Vogelmann and Gorton, 2014;Wang et al., 2014). ...
Le caroubier est un arbre méditerranéen qui est très utilisé en médecine traditionnelle et en alimentation pour son
fruit et ses graines. Les feuilles et les écorces constituent donc des sous-produits mais elles ne sont pas très
valorisées. L’objectif principal de cette étude est de distinguer les différents éléments botaniques de la feuille et
de l’écorce puis d’étudier qualitativement et quantitativement leurs composants chimiques. Il s’agit donc d’une
étude descriptive comparative par une étude macroscopique et microscopique de la coupe transversale et de la
poudre suivie d’un screening tri-phytochimique et d’un dosage spectrophotométrique des polyphénols et des
flavonoïdes de la feuille et de l’écorce du caroubier. Ces deux parties renferment des poils tecteurs et des fibres
scléreuses péricycliques mais seule l’écorce contient des cellules scléreuses, le screening phytochimique a
confirmé la présence des stérols des saponosides ainsi que des polyphénols avec 37,32 mg/g dont 24,20 mg/g de
flavonoïdes dans les feuilles et de 28,54mg/g dont 5,76mg/g de flavonoïdes dans l’écorce. Ces résultats très
encourageants doivent être complétés par des études chimiques, biologiques et cliniques plus approfondies afin de
permettre un sage thérapeutique.
The surface tension, pH and contact angle of the wetting liquid as well as the complex composition of the leaf surface are important parameters to describe the spreading, wettability and absorption of agrochemicals on the leaf surfaces. The contact angle of aqueous solutions of agrochemicals (multi-micronutrient fertilizers, growth regulator and insecticides) with/without Leaf guard, bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) and Sapindus mukorrossi (Ritha) were measured over the surface of mango leaves. The order of contact angle (mean) values was found to be AOT < Ritha < Leaf guard, which implies that AOT is a better wetting agent, but Ritha has a higher range of adhesion work because of its acidic nature (low pH). The wetting free energy was found to be more negative in the presence of Leaf guard, Ritha and AOT than in water, which indicates that wetting is more spontaneous in the presence of surfactants. The adaxial surface of mango leaves had a higher surface free energy than the abaxial part and hence showed higher wettability than the abaxial part.
This review presents the extractions, characterisations, applications and economic analyses of natural coagulant in separating pollutants and microalgae from water medium, known as microalgae harvesting. The promising future of microalgae as a next-generation energy source is reviewed and the significant drawbacks of conventional microalgae harvesting using alum are evaluated. The performances of natural coagulant in microalgae harvesting are studied and proven to exceed the alum. In addition, the details of each processing stage in the extraction of natural coagulant (plant, microbial and animal) are comprehensively discussed with justifications. This information could contribute to future exploration of novel natural coagulants by providing description of optimised extraction steps for a number of natural coagulants. Besides, the characterisations of natural coagulants have garnered a great deal of attention, and the strategies to enhance the flocculating activity based on their characteristics are discussed. Several important characterisations have been tabulated in this review such as physical aspects, including surface morphology and surface charges; chemical aspects, including molecular weight, functional group and elemental properties; and thermal stability parameters including thermogravimetry analysis and differential scanning calorimetry. Furthermore, various applications of natural coagulant in the industries other than microalgae harvesting are revealed. The cost analysis of natural coagulant application in mass harvesting of microalgae is allowed to evaluate its feasibility towards commercialisation in the industrial. Last, the potentially new natural coagulants, which are yet to be exploited and applied, are listed as the additional information for future study.
Multifunctional surfaces with reversible wetting characteristics are fabricated utilizing end-anchored polymer chains onto hierarchically roughened surfaces. Temperature- and/or pH-responsive surfaces are developed that exhibit reversible and controllable wettability, from the "parahydrophobic" behavior of natural plant leaves all the way to superhydrophilic properties in response to the external stimuli. For this purpose, dual scale micro/nano-roughened surfaces were prepared by laser irradiation of inorganic surfaces (Si wafers) utilizing ultrafast (femtosecond) laser pulses under a reactive gas atmosphere. End-functionalized polymer chains were anchored onto those surfaces utilizing the "grafting to" method; poly(N-isopropyl acrylamide), PNIPAM, and poly(2-vinyl pyridine), P2VP, were used for the formation of monofunctional as well as mixed brushes. The surfaces exhibit "parahydrophobic" behavior in the hydrophobic state (high temperature and/or high pH), with high static contact angles (~120°) and high water adhesion (~30° contact angle hysteresis), whereas they show superhydrophilic behavior in the hydrophilic state (low temperature and/or low pH). The surfaces were tested for their wettability under repetitive cycles and found to be stable and reproducible.
The effect of epicuticular wax (EW) load on the cuticular transpiration rate (T c of sorghum [ Sorghum bicolor (L.) Moench] leaves was studied. Leaves from bloom, bloomless, and sparse bloom isogenic lines and various bloom‐type hybrids were collected from field plots after anthesis in 1976, 1977, and 1981. Epicuticular wax was extracted with chloroform and quantified using a colorimetric method. The T c of detached leaves were measured with a humidity sensor in a closed cuvette or calculated from the mass of water lost per unit time under standardized conditions. The T c increased as EW decreased over the range of 0.1 to 0.03 g m ⁻² when data from all genotypes were pooled for analysis. However, among the normal (bloom) phenotypes there was no clear association between rates of water loss and EW. These data suggest that EW greater than about 0.067 g m ⁻² provide an effective barrier to water loss through cuticles of sorghum leaves under most conditions. Although the two methods of measuring T c produced the same qualitative results, T c rates calculated from the mass of water transpired under more “realistic” controlled conditions were higher and probably more directly related to rates of water loss under field conditions. Because of its speed and technical simplicity, the water loss method appears superior when large numbers of samples must be evaluated.
Four evergreen sclerophyllous species were investigated morphologically and anatomically. Buds, leaves and roots from Ceratonia siliqua, Olea europaea, Pistacia lentiscus and Quercus coccifera were studied and compared for structural diversity. Analysis of the anatomical data suggested diverging features. The ecological equivalence of these species cannot be attributed to their structure.
The objective of this study was to investigate patterns of surface features of leaves related to susceptibility to wetness for plants along a strong precipitation gradient. Leaf wettability and droplet retention were examined for leaves of 37 species (representing 28 families) occurring in steppe, ecotone, and temperate rain forest habitats along a steep moisture gradient in northwestern Patagonia, Argentina. Morphological and structural characteristics of leaves significantly affected leaf surface wetness, and these characteristics varied between habitats. Typically, leaves had more stomata on abaxial than adaxial leaf surfaces (P < 0:0001). Droplet retention and leaf wettability (u) were negatively correlated (Spearman r ! " 0:694; P < 0:0001). Leaves in dry habitats tended to be less wettable and less likely to retain droplets on the leaf surface; however, overall differences were not significant. The presence of trichomes significantly reduced wettability (P < 0:05). The high frequency and natural variability of wetting events in these and a great variety of other habitats, coupled with the large range in surface wettability among plant species and the potentially strong effects on photosynthesis, growth, and pathogen infections, suggest an important evolutionary avenue related to the dynamics of water on leaf surfaces.
Palynology provides information about Pliocene and early Pleistocene vegetation and climate evolution inthe north-west Mediterranean area in relation to high northern latitude climatic trends. An important change occurred approximately 3.2 Myr ago with the appearance of the Mediterranean climatic rhythm (summer drought) causing the individualization of the modern Mediterranean floral elements. Quaternary-type mediterranean climatic fluctuations started approximately 2.3 Myr ago (early Glacial) causing the Mediterranean-type of vegetational organization.
Above-ground parts of Phaseolus vulgaris L. plants were treated with artificial misty rain (‘rain’) in a growth chamber to investigate the effects of leaf wetness on photosynthetic performance. The following results were obtained. (1) Stomata closed completely within 2 min of the onset of continuous ‘rain’ application and gradually opened to half the original aperture by 60 min. The rate of CO2 exchange measured on such wet leaves changed in parallel with the changes in stomatal aperture and attained 60 to 70% of the control level by 1h. (2) The dependence of the rate of leaf photosynthesis, A, on the intercellular CO2 concentration, ci [A(ci) relationship], examined in thoroughly dried leaves which had been treated with ‘rain’ did not change until after 4 h of treatment. However, leaves treated for 6h showed discernible decreases in A at high ci (ci>500μmolmol −1). The photosynthetic rate of leaves treated with ‘rain’ for 24 h was reduced at all ci, and A at the ambient CO2 concentration of 350μmolmol−1 was 60 to 70% of that of the control level. The rate of photosynthesis did not recover even after 3 d of treatment of the plants in a dry environment. These results clearly indicate that leaf wetness causes not only instantaneous suppression of photosynthesis but also chronic damage to the photosynthetic apparatus. Potential effects of leaf wetness on photosynthetic performance in nature are also discussed.
The present study aims at investigating the role of leaf morphological features and their relation to leaf surface wettability for important medicinal and aromatic plants of Western Himalaya. The surface features related to leaf wettability were studied in 30 plant species representing 21 different families growing under open and shade conditions. The leaf surfaces with the highest density of trichomes and stomata per unit area were found to be the least wettable, regardless of condition type. Most of the species of both conditions were hypostomatic, and per unit area concentration of stomata contributes more than stomatal size to stomatal area index. Leaf surfaces of open condition species were more water repellent with higher stomatal density, and had lower water droplet retention than shade species. It is suggested that leaf morphological features (stomata and trichome) had a strong influence in reducing the leaf area with surface moisture, which could be correlated with the frequency and duration of leaf wettability in a given condition.
The possibility of utilising chopped and deseeded carob pods (kibbles) as a source of polyphenolic antioxidants was examined by performing extractions with various solvent systems, in order to evaluate and optimize the conditions for the recovery of polyphenols. Maximum quantities of polyphenolic components were found in 80 % acetone extracts, as evaluated by measuring total polyphenol and total flavanol content. By contrast, ethyl ace-tate was inefficient in extracting polyphenols. The assessment of the antioxidant potency of carob pod extracts employing two characteristic in vitro models showed that carobs con-tain polyphenols with appreciable antiradical and reducing properties. The values obtained were compared to the data on red wines and pure polyphenolic antioxidants.
A late Holocene pollen profile from the Megaris on the eastern Gulf of Corinth shows a vegetation which was strongly influenced by human impact throughout. A Pistacia-Phillyrea maquis, which is reflected in the older parts of the profile, changed later to a more degraded vegetation type. In the uppermost part Pinus dominates the pollen spectrum. A continuous record of Ceratonia siliqua pollen older than cal a.d. 100 is of special interest.
The aim of this study is to investigate cell adhesion and viability on highly rough polymeric surfaces with gradient roughness ratios and wettabilities prepared by microreplication of laser micro/nano-textured Si surfaces. Negative replicas on polydimethylsiloxane as well as positive ones on a photocurable (organically modified ceramic) and a biodegradable (poly(lactide-co-glycolide)) polymer have been successfully reproduced. The final culture substrates comprised from forests of micron-sized conical spikes exhibiting a range of roughness ratios and wettabilities, was achieved by changing the laser fluence used to fabricate the original template surfaces. Cell culture experiments were performed with the fibroblast NIH/3T3 and PC12 neuronal cell lines in order to investigate how these surfaces are capable of modulating different types of cellular responses including, viability, adhesion and morphology. The results showed a preferential adhesion of both cell types on the microstructured surfaces compared to the unstructured ones. In particular, the fibroblast NIH/3T3 cells show optimal adhesion for small roughness ratios, independent of the surface wettability and polymer type, indicating a non-monotonic dependence of cell adhesion on surface energy. In contrast, the PC12 cells were observed to adhere well to the patterned surfaces independent of the roughness ratio and wettability. These experimental findings are correlated with micromechanical measurements performed on the unstructured and replicated surfaces and discussed on the basis of previous observations describing the relation of cell response to surface energy and rigidity.
This paper reviews our work on the application of ultrafast pulsed laser micro∕nanoprocessing for the three-dimensional (3D) biomimetic modification of materials surfaces. It is shown that the artificial surfaces obtained by femtosecond-laser processing of Si in reactive gas atmosphere exhibit roughness at both micro- and nanoscales that mimics the hierarchical morphology of natural surfaces. Along with the spatial control of the topology, defining surface chemistry provides materials exhibiting notable wetting characteristics which are potentially useful for open microfluidic applications. Depending on the functional coating deposited on the laser patterned 3D structures, we can achieve artificial surfaces that are (a) of extremely low surface energy, thus water-repellent and self-cleaned, and (b) responsive, i.e., showing the ability to change their surface energy in response to different external stimuli such as light, electric field, and pH. Moreover, the behavior of different kinds of cells cultured on laser engineered substrates of various wettabilities was investigated. Experiments showed that it is possible to preferentially tune cell adhesion and growth through choosing proper combinations of surface topography and chemistry. It is concluded that the laser textured 3D micro∕nano-Si surfaces with controllability of roughness ratio and surface chemistry can advantageously serve as a novel means to elucidate the 3D cell-scaffold interactions for tissue engineering applications.
Many plant surfaces are water-repellent because of a complex 3-dimensional microstructure of the epidermal cells (papillae) and a superimposed layer of hydrophobic wax crystals. Due to its surface tension, water does not spread on such surfaces but forms spherical droplets that lie only on the tips of the microstructures. Studying six species with heavily microstructured surfaces by a new type of confocal light microscopy, the number, height, and average distance of papillae per unit area were measured. These measurements were combined with those of an atomic force microscope which was used to measure the exposed area of the fine-structure on individual papillae. According to calculations based upon these measurements, roughening results in a reduction of the contact area of more than 95% compared with the projected area of a water droplet. By applying water/methanol solutions of decreasing surface tension to a selection of 33 water-repellent species showing different types of surface structures, the critical value at which wetting occurs was determined. The results impressively demonstrated the importance of roughening on different length scales for water-repellency, since extremely papillose surfaces, having an additional wax layer, are able to resist up to 70% methanol. Surfaces that lack papillae or similar structures on the same length scale are much more easily wetted.
The approximate composition and mineral contents of carob fruit (Ceratonia siliqua), and the traditional foods produced from this fruit, carob flour and carob syrup, were studied. Protein, crude fiber and ash content and energy values of carob syrup were lower than the values of both carob fruit and carob flour. According to the results, the total sugar content, the most important constituents of carob products, were 48.35%, 41.55% and 63.88% for fruit, flour and syrup, respectively. These products contained high amounts of calcium, potassium, magnesium, sodium and phosphorus, which were the most abundant elements in carob fruits (P < 0.05). Among the samples, potassium, phosphorus and calcium had the highest values in carob syrup, respectively. Carob flour also contained these elements in high amounts, with the addition of sodium. We extended the notion that carob fruit, flour and syrup were rich sources of carbohydrates, proteins and minerals.
A much clearer picture is now emerging of the fine structure of the plant cuticle and its surface, the composition of cuticular waxes and the biosynthetic pathways leading to them. Studies assessing the impact of UV radiation on plant life have emphasized the role of the cuticle and underlying epidermis as optical filters for solar radiation. The field concerned with the diffusive transport of lipophilic organic non-electrolytes across the plant cuticle has reached a state of maturity. A new paradigm has recently been proposed for the diffusion of polar compounds and water across the cuticle. In the context of plant ecophysiology, cuticular transpiration can now be placed in the perspective of whole-leaf water relations. New and unexpected roles have been assigned to the cuticle in plant development and pollen-stigma interactions. Finally, much progress has been made in understanding the cuticle as a specific and extraordinary substrate for the interactions of the plant with microorganisms, fungi and insects. This volume details the major developments of recent years in this important interdisciplinary area. It is directed at researchers and professionals in plant biochemistry, plant physiology, plant ecology, phytopathology and environmental microbiology, in both the academic and industrial sectors.
Hoffmann (1878) made direct observations on the leaf longevity of six dicotyledonous evergreen species growing in the Botanical Garden, at Giessen, Germany. Among these species were Olea europaea and Laurus nobilis for which he found a leaf life times of 13–26 and 17–53 months respectively.
Many plant surfaces are water‐repellent because of a complex 3‐dimensional microstructure of the epidermal cells (papillae)
and a superimposed layer of hydrophobic wax crystals. Due to its surface tension, water does not spread on such surfaces but
forms spherical droplets that lie only on the tips of the microstructures. Studying six species with heavily microstructured
surfaces by a new type of confocal light microscopy, the number, height, and average distance of papillae per unit area were
measured. These measurements were combined with those of an atomic force microscope which was used to measure the exposed
area of the fine‐structure on individual papillae. According to calculations based upon these measurements, roughening results
in a reduction of the contact area of more than 95% compared with the projected area of a water droplet. By applying water/methanol
solutions of decreasing surface tension to a selection of 33 water‐repellent species showing different types of surface structures,
the critical value at which wetting occurs was determined. The results impressively demonstrated the importance of roughening
on different length scales for water‐repellency, since extremely papillose surfaces, having an additional wax layer, are able
to resist up to 70% methanol. Surfaces that lack papillae or similar structures on the same length scale are much more easily
Although numerous studies have considered the functional significance of the terrestrial plant leaf surface, the importance of water repulsion for enhancing photosynthetic carbon uptake (CO,) has not been recognized and appears to involve an array of structural adaptations. The large majority of species tested had leaf surfaces that repelled water to such an extent that varying degrees of water-bead formation occurred. On more wettable leaves, the formation of a water surface film (dewfall) severely curtailed photosynthetic CO, uptake in the field, most likely because CO, diffuses 104 times slower in water than air. Water bead formation not only enabled maintenance of high photosynthetic rates but also increased water use efficiency several fold. In 3 of 5 species tested in the field, water bead formation after artificial wetting resulted in greater stomatal opening and increases in photosynthesis of up to 34%. The most nonwettable leaf surface on a given leaf also had all or the majority of the leaf's stomata in 50 of the 57 species tested, indicating a potentially strong adaptive relationship between leaf surface wettability, stomatal occurrence, and photosynthetic performance. MOST GEOGRAPHIC locations experience some form of predictable precipitation that wets terrestrial plant leaves for substantial periods. This precipitation may come as rainfall, dew, ground fog, or cloud mist. Although there are numerous studies considering the importance of leaf surface wetness to pathogen invasion and chemical exchange (Martin and Juniper, 1970; Blakeman, 1980; Juniper and Jeffree, 1983), plus a continuing interest in the possibility of
Recent advances in the area of the wetting of leaf areas are reviewed with particular emphasis on their relation to agrochemical application. Areas reviewed include leaf wax composition, leaf wetting and superhydrophobicity, agrochemical deposit formation and spray retention. It is thought that most progress has been made in the area of leaf wetting through the work on lotus leaves. In the area of spray retention, factors such as plant type, spray solution properties and weathering of the plants are found to be keys. Recent progress in the modelling of spray retention is also discussed.
Aerosols have always been part of the atmosphere, and plant surfaces are a major aerosol sink. Given the nutrient content of aerosols and the natural stability of aerosol concentrations over evolutionary time, plants may have developed adaptations to aerosol input. Although little is known about such adaptations, leaf surface micro-roughness appears to play a key role. This review focuses on the deposition and fate of fine aerosols that are less than 2.5 μm in diameter. Most of these aerosols are hygroscopic, and they are often deliquescent (liquid) on transpiring leaves. Such concentrated solutions may be taken up by both the cuticle and stomata, contradicting previous concepts. The establishment of a continuous liquid water connection along stomatal walls affects individual stomata and is a new concept called "hydraulic activation of stomata" (HAS). HAS enables the efficient bidirectional transport of water and solutes between the leaf interior and leaf surface and makes stomatal transpiration partly independent of stomatal aperture. The response of plants to changes in humidity can be explained by the split transpiration in an HAS pore and its interaction with neighboring stomata, i.e., as an emergent property of a stomatal patch. Normally, HAS affects only a few stomata, but if too many are activated by excessive particle accumulation or additional surfactants, hygroscopic particles may work as "desiccants," reducing the drought tolerance of plants. This is made use of when hygroscopic salts and acids are sprayed to kill potato vine, but may cause problems in foliar fertilization. Excessive particle accumulation may also be caused by air pollution. It is hypothesized that deliquescent hygroscopic particles, due to their amorphous appearance, may have been misinterpreted as "degraded waxes." Degraded waxes have been highly correlated to leaf loss, decreased drought tolerance, and decreased frost tolerance of trees. No sound explanation for degraded waxes has been found, and they have been interpreted as symptoms of forest decline. Because hygroscopic particles may affect the drought tolerance of trees, they could be drivers of regional tree die-off and especially affect those trees that have adapted to capture aerosols. Several research questions are identified.
Available archaeo-botanical finds (most of them from Israel) show that the carob Ceratonia siliqua L. existed in the Eastern Mediterranean basin long before the start of agriculture. Early literary sources indicate that its domestication took place relatively late (only in Roman times). The probable reason for this late date is that the carob does not lend itself to simple vegetative propagation, and its cultivation had to wait until the introduction of scion grafting into the Mediterranean basin. Carob culture reached its peak in this region in early Islamic times. C. siliqua cultivars and wild-growing trees frequently grow side by side, and intercross rather freely. It is proposed that under domestication, hermaphroditic clones were favored, causing a partial breakdown of dioecy in carob culture. Through introgression, this development also affected some of the wild populations.
Residual transpiration rates, epicuticular wax loads and leaf colours of 20 cultivars of pea (commercial varieties and bred, improved lines) were studied. The residual transpiration rate varied between genotypes from 0.77 to 1.82 mg m−2 s−1, while wax content varied between 0.19 and 0.41 g m−2. Leaf colour varied on the Munsell colour saturation scale between 4 and 8. No significant correlation was found between epicuticular wax load and residual transpiration rate. This suggests that all the studied varieties have more than enough wax to be able to adequately control the loss of water from the cuticle. The differences between cultivars in residual transpiration rates are therefore due to other factors. No significant changes in residual transpiration rate were seen in any of the genotypes studied when subjected to drought, with the exception of variety 53. However, in the majority of varieties, the epicuticular wax load increased significantly when plants were subjected to this treatment. All three studied parameters affected the performance of pea plants under drought. A positive correlation (P
The influence of the suface roughness of paraffin wax surfaces on the static and dynamic contact angle hysteresis is investigated by means of the Wilhelmy method and water, ethylene glycol as well as ethanol as test liquids at 20°C in order to estimate the true Young’s equilibrium contact angles. These angles can be derived from the quasistatic contact angle hysteresis data as produced by roughness variatiom using the presented empirical model.
In the present study seasonal changes of chlorophyll content and storage substances related to the metabolic response of the widespread, evergreen plant oleander (Nerium oleander) to air pollution were investigated. Mature leaves of oleander shrubs, grown at five sites of differing levels of air pollution in the center and the suburbs of the Athens Metropolitan area, were examined during the course of a year. Soluble sugars, starch and total lipid content of the leaves showed a peak at the end of the cold season, while a decline was detected during the main growth period. Leaf chlorophyll content was increased during spring. It seems likely that the level of air pollution in Athens did not affect the concentration and the seasonal pattern of storage substances at the leaf level. Elevated chlorophyll content was estimated in the polluted with oxides of nitrogen sites. In contrast, leaf chlorophyll content declined in sites with ozone pollution.
The central cylinder of the primary root of the carob tree (Ceratonia siliqua) is encircled by a layer of cells with wall thickenings, known as a phi (φ) cell layer. The development of the φ layer and the chemical composition of the cell wall thickenings have been studied in roots of C. siliqua. The results reveal the presence of condensed tannins in the mature phi thickenings and that the development of the φ layer is asynchronous: at 0–1 cm from the root tip φ thickenings appear before endodermis differentiation at the sites opposite phloem, at 1–4 cm new φ thickenings are developed at the sites opposite xylem, at 4–7 cm the φ layer consists of two layers of cells and it completely encloses the central cylinder.
Experiments are described which provide more information on the role played by superficial waxes in the natural water-repellency of leaf surfaces. Contact angles of water were measured on a variety of leaf surfaces, before and after removal of wax, and on smooth films of the isolated superficial waxes. The differences in wettability of leaf surfaces are not wholly accounted for by differences which occur in the chemical and hydrophobic properties of their superficial waxes.
Waxes isolated from leaves exhibiting contact angles less than 90° are usually more hydrophobic than the leaf surface itself. On most leaves exhibiting angles greater than 90° wax is the dominant factor governing water-repellency, the isolated wax normally making at least a 60 % contribution to the contact angle measured on the leaf surface. Additional factors, such as roughness, responsible for the occurrence of contact angles greater than 110° on certain leaf surfaces, reside in the wax layer. The hydrophobic properties of some leaves are unaffected by chloroform washing, revealing that superficial waxes play little part in their wettability.
A study was conducted to demonstrate the quantitative reproduction of water repellency of a lotus leaf, using biomimetic artificial surfaces. It was demonstrated that the surface possesses a hierarchical morphology with two length-scale roughnesses combined with a proper hydrophobic chemistry. The water repelling characteristics of the surfaces were quantified by investigating the bouncing of free-falling water droplets impacting into them as a function of impact velocity. It was also demonstrated that the repellency of the artificial surface can be favorably compared to that of the lotus leaf, in terms of the threshold velocity, which is sufficient to avoid sticking of the droplets. It was observed that the collision energy loss and the remaining wetting of the surfaces progress at high velocities during the process.
The aim of the study was to determine the main sugar profiles of the pods, without the seeds, of cultivated and wild types of the carob bean grown in the Mediterranean and Aegean basin of Turkey. The most abundant sugar in the pods was sucrose with smaller amounts of glucose and fructose. The pods of cultivated varieties had a higher (p < 0.05) total sugar concentration of 531 ± 93 g/kg dry weight than the wild type selections which had 437 ± 77 g/kg. However, this difference was due to the greater concentration of sucrose in the cultivated varieties which did not differ from the wild types in their concentrations of fructose or glucose. The ratios of individual sugars to total sugars in the pods were similar in both varieties. There is a need to identify extreme wild types, including high seeds and low pod, and cultivated types, containing low seeds and high pod, rich in sugar for an exhaustive picture of the sugar profiles of the varieties.
Rates of photosynthesis and leaf conductance of the leaves of carob trees (Ceratonia siliqua L.) growing in natural conditions were measured during the course of the seasons to define the effects of the main climatic factors limiting growth in the region: temperature during the winter and water in the summer. The highest photosynthetic rates were measured in spring and autumn and could reach 25 μmol m−2 s−1 with optimal temperature and available water. Due to lower temperatures (4 to 6°C in the night) these values were frequently around 15 μmol m−2 s−1 during winter, but the strongest depression was due to prolonged drought in summer. However a reduction in photosynthesis rate down to 5 μmol m−2 s−1 occurred only after depletion of all the available water in the soil layer up to a depth of 50 cm. In the end of the summer, leaf conductance and water potential were in the order of 20 mmol m−2 s−1 and −3 MPa respectively. Compared to other trees that make up the Mediterranean sclerophyll forest, the photosynthetic activity of carob is high, and the tree tolerates a considerable depletion of soil water.
Cultivars of common wheat (Triticum aestivum L.) and durum wheat (T. turgidum L. var. durum) were evaluated for epicuticular wax content and its relationship with spectral reflectance. Epicuticular wax is associated with drought tolerance. Highly significant differences (1.51 to 2.80 mg/dm2) were found in the amount of epicuticular wax (EW) among the cultivars. Water stress significantly enhanced the level of EW. EW content under stress and control conditions were positively correlated (r=0.85, p was positively correlated with the amount of EW (r=0.59, p
Biological surfaces provide multifunctional interfaces to their environment. More than 400 million years of land plants evolution led to a large diversity of functional biological surface structures. This article provides an overview of the most frequently functional surface structures of plants. It focuses on functional adaptations of plant surface structures to environmental conditions. The structural and functional relationships of plants growing in deserts, water and wetlands are discussed. The article is written for both biologists and non-biologists and should stimulate the readers to initiate or intensify the study of functional biological surfaces and their potential for technical use, leading to, so called, biomimetic inspired smart surfaces. For a broader understanding of the structural diversity in plants, the origin of surface structuring is introduced from the sub-cellular level up to multi-cellular structures. Functional aspects of plant surface structures include the reduction of particle adhesion and the self-cleaning properties in the Lotus (Nelumbo nucifera) leaves. These surface properties are based on physico-chemical principles and can be transferred into technical “biomimetic” materials, as successfully done for the Lotus leaves. In plants, several other functional structures, e.g., for the absorption of water or light reflection, exist. Some, which might be useful models for the development of functional materials, are introduced here and some existing technical applications and fabrication techniques for the generation of biomimetic surfaces are discussed.
Multi-use tree plantations are a major component of the traditional rural landscapes of semiarid Mediterranean regions. Having evolved over centuries, these landscapes are the product of sustainable development. Within their flexible spatial format, agricultural, silvicultural, and pastoral production is combined to provide efficient use of the natural and human resources. Oliver and carob tree plantations in the Girne region of North Cyprus are chose as an example of these traditional landscapes. They are evaluated according to information gathered from field surveys in two sample locations: one in rural marginal lands; the other, a few kilometres to the east of Girne town. The findings indicate that these landscapes are undergoing a process of degradation and fragmentation owing to economic and socio-cultural factors.The objective of the present study is fourfold: (1) to determine the structure, distribution pattern, and management of these traditional landscapes; (2) to evaluate the pattern and causes of their degradation; (3) to draw attention to their ecological and cultural significance within the context of the Girne region: (4) to propose alternative roles that will allow them to become integrated into future developments.The study reviews the potential of tourism to provide a context for the appreciation and protection of these traditional landscapes. The Dik Burun tourist project is reviewed as an example of local-scale application of such an alternative. Landscapes of multi-use olive and carob plantations are incorporated into the project master plan, ensuring not only their protection, but also their continued contribution towards enhancing the ecological, cultural and aesthetic character of the region.
Surface properties of barley straw (Hordeum vulgare) play a crucial role in some industrial applications such as sorption in oil spills and soil clean-up. In this paper, the chemical and morphological heterogeneities of barley straw leaf and stem surfaces were investigated by water and oil contact angle measurements, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The differences in the contact angles for internal versus external stem and leaf surfaces are explained by the presence of a complex wax layer at the external surface as revealed by FTIR external reflection spectroscopy. Wax composition was determined by transmission FTIR spectroscopy. SEM images confirmed the heterogeneity and complexity of the wax crystal structure of the outer stem surface. AFM measurements complemented the SEM analysis by providing additional structural details including a measure of surface roughness.
Leaf water relationships were studied in eleven evergreen sclerophyll species from a macchia near Athens, Greece. Water (ψ), solute (ψs) and turgor (ψp) potentials as well as relative water content (RWC) and stomatal conductance were measured during the course of a year. Relatively high values of water potential were measured initially in the young expanding leaves during the 60-90 d of the growth period. After this period a soil moisture deficit developed and leaves increased to full size. During the drought period leaf water potential and solute potential values, as well as stomatal conductance were low. The results show that during the dry season (Jun.-Aug.) all species are at or near zero turgor and this occurs in Arbutus, Myrtus and Nerium at around -1.5 MPa, in Ceratonia, Pistacia and Quercus at around -2.0 MPa, in Laurus, Olea and Phillyrea below -3·5 MPa. These values largely reflect differences in ψs at this time. Also, the seasonal variations in the water relations components reflect the responses of the different species to variation in water availability.
Seedlings of Ceratonia siliqua L., an evergreen sclerophyll species native to the Mediterranean region, were grown in 30-cm deep tubes of John Innes II potting
compost in a growth cabinet maintained at 15 ~ C during a 12-h day where PAR was 400 gmol m-2 s-1. After a period of acclimatisation to the conditions in the cabinet
during which plants were watered every day, water was withheld from the soil in some tubes for 24 days. These conditions may be regarded as a simulation of the natural
situation. Estimates of leaf and root water potential and solute potential, leaf growth and root development were made at intervals during the soil drying cycle on both
watered and unwatered plants. Water potential and solute potential measurements were made both on young expanding and on fully expanded leaves. During the
experimental period, root growth of C. siliqua was not much affected by soil drying, and roots in both the watered and the unwatered columns penetrated to the
bottom of the soil tubes by the end of the drying treatment. Expanded leaves showed significant limitation in stomatal conductance as soil drying progressed. Leaf water potential of fully expanded leaves of unwatered plants declined substantially. In contrast, water potential of young expanding leaves on unwatered plants declined
to only a limited extent and turgor was sustained. As the soil dried, stomatal conductance of young leaves was always higher than that of mature leaves; also, placticity and elasticity of young leaves slowly decreased whereas mature leaves became stiff. Changing leaf cell wall properties may determine different patterns of water use as the leaves age. A mechanism of continuous diffusion of water through the soil towards the tip and pumping towards the young leaves is proposed.
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.
The water relations, stomatal conductance, size, chlorophyll and proline content have been measured in sun and shade leaves
of four evergreen sclerophyll species, throuthout the year. It was found that there were no major differences in water status
of the two leaf types. However, in young expanding shade leaves, higher stomatal conductance, turgor, chlorophyll and proline
content leves was significantly larger. Plastochron ratios of the two leaf types in the four species were similar, indicating
a synchronized gorwth rate related to seasonal rhythemicity. It is suggested that different mechanisms have been operating
in the response of the two leaf-types to microclimatic conditions: an avoidance by sun leaves and tolerance by shade leaves.
Plant surfaces are characterized by a high diversity of structures which determine their optical properties, such as shiny, gleaming, silky, matt or iridescent. Replicas with different optical properties have been generated by using plant surfaces as templates and an improved replica technique. The technique allows the replication of complex surface structures with overhangs, cavities, and fragile or soft structures in a fast and cost-efficient way. Structures from some millimetres to some nanometres can be replicated. The transfer of complex architectures with different optical properties from plant surfaces onto technical surfaces implies a great potential for the development of new biomimetic surfaces with new optical properties.
The leaf cuticular waxes of three Salix species and two Populus species hybrids, selected for their ability to produce high amounts of biomass, were characterized. Samples were extracted in CH(2)Cl(2) three times over the growing season. Low kV SEM was utilized to observe differences in the ultrastructure of leaf surfaces from each clone. Homologous series of wax components were classified into organic groups, and the variation in wax components due to clone, sample time, and their interaction was identified. All Salix species and Populus species hybrids showed differences in total wax load at each sampling period, whereas the pattern of wax deposition over time differed only between the Salix species. A strong positive relationship was identified between the entire homologous series of alcohols and total wax load in all clones. Similarly strong relationships were observed between fatty acids and total wax load as well as fatty acids and alcohols in two Salix species and one Populus species hybrid. One Salix species, S. dasyclados, also displayed a strong positive relationship between alcohols and alkanes. These data indicate that species grown under the same environmental conditions produce measurably different cuticular waxes and that regulation of wax production appears to be different in each species. The important roles cuticular waxes play in drought tolerance, pest, and pathogen resistance, as well as the ease of wax extraction and analysis, strongly suggest that the characteristics of the cuticular wax may prove to be useful selectable traits in a breeding program.
Super-hydrophobic surfaces as well as low adhesion and friction are desirable for various industrial applications. Certain plant leaves are known to be hydrophobic in nature. These leaves are hydrophobic due to the presence of microbumps and a thin wax film on the surface of the leaf. The purpose of this study is to fully characterize the leaf surface and to separate out the effects of the microbumps and the wax on the hydrophobicity. Furthermore, the adhesion and friction properties of the leaves, with and without wax, are studied. Using an optical profiler and an atomic/friction force microscope (AFM/FFM), measurements on the hydrophobic leaves, both with and without wax, were made to fully characterize the leaf surface. Using a model that predicts contact angle as a function of roughness, the roughness factor for the hydrophobic leaves has been calculated, which is used to calculate the contact angle for a flat leaf surface. It is shown that both the microbumps and the wax play an equally important role in the hydrophobic nature as well as adhesion and friction of the leaf. This study will be useful in developing super-hydrophobic surfaces.
Plant surfaces are the interfaces of the organisms with respect to their environment. In the micro-dimension they show an enormous variety of functional three-dimensional structures. Their materials and structures developed over millions of years by evolutionary processes in which their functionality has been proven and selected by environmental pressures. As a result, nature developed highly functional materials with several amazing properties like superhydrophobicity and superhydrophilicity. These functional structures are built up by a complex biopolymer called cuticle. The cuticle is mainly composed of a three-dimensional network of cutin, and integrated and superimposed lipids called "waxes". Superimposed waxes are also called "epicuticular waxes". Epicuticular waxes often form two- and three-dimensional structures, in dimensions between hundreds of nanometers and some micrometers, which influence the wettability, self-cleaning behaviour and the light reflection at the cuticle interface. This review gives a brief introduction into the functions of the plant epicuticular waxes and summarises the current knowledge about their morphologies, crystal structures, growth by self-assembly and provides an overview about the microscopy and preparation techniques for their analysis.
Vitrification is a morphological and physiological disorder affecting plants during their in vitro vegetative propagation. Vitrified plants have a poor survival rate when transferred from in vitro to greenhouse conditions, a fact mainly due to water loss and dissecation. It has been shown that normal and vitreous leaves
of Datura insignis differ in the frequency of normal and abnormal stomata. The purpose of this work was to compare the surface of normal and
vitreous leaves of D. insignis, using a modification of the platinum/carbon replica method. Adaxial and abaxial leaf surfaces of normal plantlets have a
smooth and homogenous cuticle. A granular aspect, probably due to leaf age, rarely occurs at the periphery of the epidermal
cells. Both adaxial and abaxial leaf surfaces of vitrified plantlets show discontinuities in the cuticle, occurring at several
regions of the outer periclinal cell walls. However, such discontinuities are most noticeable in the region between adjacent
epidermal cells. Fibrils 20–30 nm thick show a random arrangement or an oriented pattern in cuticular discontinuities. In
D. insignis vitrified plantlets, adaxial and abaxial leaf cuticle has discontinuities or gaps which may cause an increase in cuticular
transpiration contributing to the low survival rate of vitrified plantlets.
Controlling cell adhesion via replication of laser micro/nano-textured surfaces on polymers The changing role of rural landscapes: olive and carob multi-use tree plantations in the semiarid Mediterranean
K E Aifantis
Koufaki, N., Ranella, A., Aifantis, K.E., Barberoglou, M., Psycharakis, S., Fotakis, C., Stratakis, E., 2011. Controlling cell adhesion via replication of laser micro/nano-textured surfaces on polymers. Biofabrication 3, 045004. Makhzoumi, J.M., 1997. The changing role of rural landscapes: olive and carob multi-use tree plantations in the semiarid Mediterranean. Landscape Urban Plan. 37, 115–122.
Some aspects of the structure and regulation of Ceratonia siliqua L. stomata
M A Nunes
H F Linskens
Nunes, M.A., Linskens, H.F., 1980. Some aspects of the structure and regulation of
Ceratonia siliqua L. stomata. Portug. Acta Biol. 16, 165-174.
The carob tree: an exemplary plant
Catarino, F., 1993. The carob tree: an exemplary plant. Naturopa 73, 14-15.
Biomimetic replicas: transfer of complex architectures with different optical properties from plant surfaces onto technical materials
A J Schulte
Schulte, A.J., Koch, K., Spaeth, M., Bathlott, W., 2009. Biomimetic replicas: transfer
of complex architectures with different optical properties from plant surfaces
onto technical materials. Acta Biomater. 5, 1848-1854.