555 research outputs found
Advanced Greenhouse Horticulture
No full textGreenhouse horticulture is one of the most intensive agricultural systems, focusing on the production of high-value products. This book presents current research findings that cover a wide range of new technologies and novel agricultural practices, which are preconditions for successful production in a very competitive global environment
The Δρομοδείχτης της Ελλάδος of 1824 and Athanasios Stageirites (Τίτλος περίληψης)
No full textσ. [281]-290Κείμενο στα ελληνικά με περίληψη στα αγγλικά με τον τίτλο: The Δρομοδείχτης της Ελλάδος of 1824 and Athanasios StageiritesThe article first examines the close relationship between the publication “Δρομοδείχτης της Ελλάδος” [1824] and the publication “Ηπειρωτικά” (1819) by Athanasios Stageirites and then suggests that Athanasios Stageirites is the likeliest author of the “Δρομοδείχτης της Ελλάδος”.Δωδώνη: Τεύχος Πρώτο: επιστημονική επετηρίδα του Τμήματος Ιστορίας και Αρχαιολογίας της Φιλοσοφικής Σχολής του Πανεπιστημίου Ιωαννίνων; Τόμ. 43-44 (2014-2015
Dataset in support of the Southampton doctoral thesis 'The boatbuilding tradition of the Aegean during the Late Neolithic – Early Bronze Age periods. Typological classification, digital reconstruction and seakeeping assessment'
No full textDataset in support of the Southampton doctoral thesis 'The boatbuilding tradition of the Aegean during the Late Neolithic – Early Bronze Age periods. Typological classification, digital reconstruction and seakeeping assessment' Appendix D - Resistance data and Appendix C - Stability data.
This dataset is focused on two appendices:
Appendix D - Resistance data. D.1 Resistance data produced by the author via MAXSURF Resistance for this thesis.
Appendix C - Stability data
C1. Stability data – STIX and ISO criteria, produced by the author via MAXSURF Stability software for his thesis
This research was funded by Southampton Marine and Maritime Institute (SMMI), Vice-Chancellor's Scholarship, Greek Archaeological Committee UK (GACUK)
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Advanced Greenhouse Horticulture: New Technologies and Cultivation Practices
No full textGreenhouse horticulture is one of the most intensive agricultural systems, with the advantages of environmental parameter control (temperature, light, etc.), higher efficiency of resource utilization (water, fertilizers, etc.) and the use of advanced technologies (hydroponics, automation, etc.) for higher productivity, earliness, stability of production and better quality. On the other hand, climate change and the application of high inputs without suitable management could have negative impacts on the expansion of the greenhouse horticulture sector. This special issue gathers twelve papers: three reviews and nine of original research. There is one review that focuses on irrigation of greenhouse crops, while a second surveys the effects of biochar on container substrate properties and plant growth. A third review examines the impact of light quality on plant–microbe interactions, especially non-phototrophic organisms. The research papers report both the use of new technologies as well as advanced cultivation practices. In particular, new technologies are presented such as dye-sensitized solar cells for the glass cover of a greenhouse, automation for water and nitrogen deficit stress detection in soilless tomato crops based on spectral indices, light-emitting diode (LED) lighting and gibberellic acid supplementation on potted ornamentals, the integration of brewery wastewater treatment through anaerobic digestion with substrate-based soilless agriculture, and application of diatomaceous earth as a silica supplement on potted ornamentals. Research studies about cultivation practices are presented comparing different systems (organic-conventional, aeroponic-nutrient film technique (NFT)-substrate culture), quantitative criteria for determining the quality of grafted seedlings, and of wild species as alternative crops for cultivation
Evaluation of Ascophyllum nodosum and Sargassum spp. Seaweed Extracts’ Effect on Germination of Tomato Under Salinity Stress
No full textAbiotic stresses like salinity are proven to be crucial limiting factors in the seed germination of many plant species and the later establishment of cultivation regarding plant growth, yield and fruit quality. Therefore, there is a pressing need to find practices and materials to enhance abiotic stress tolerance from early stages such as germination so that plants can overcome these stresses as soon as possible. A total of six treatments of seaweed extracts [1, 2 and 3% of Algit Super (Ascophyllum nodosum) and Alga 300 (Sargassum spp.)] and three controls were tested, with 20 seeds per replication soaked in each extract concentration for 15′; four replications were carried out per treatment and seeds were placed on Petri dishes in the dark. Speed and percentage of germination, vigor index I and II, dry weight and average lengths of roots and shoots were evaluated under 75 mM NaCl stress. All treatments positively affected all parameters evaluated, whether significant or not. Results indicate that soaking tomato seeds in seaweed extracts of various concentrations led to a significantly increased speed and percentage of germination, vigor index I and II, dry weight and average lengths of roots and shoots. The best combination of concentration and seaweed species is concluded to be 2% Sargassum spp. for all parameters evaluated
<i>Ascophyllum nodosum</i> and Silicon-Based Biostimulants Differentially Affect the Physiology and Growth of Watermelon Transplants under Abiotic Stress Factors: The Case of Drought
No full textClimate change is an inevitable process characterized by an abrupt increase in global temperature and a decrease in precipitations leading to drought incidents. Biostimulants could be a valuable tool for mitigating these harsh conditions. The objective of our study was to test the efficiency of two biostimulants, a silicon-based seaweed and the seaweed Ascophyllum nodosum, to mitigate the drought stress endured by watermelon transplants during the first few weeks after transplanting. In order to achieve this, three water treatments (100%, 75%, and 50% of field capacity) were applied in pots. Important growth parameters (leaf number, fresh weight, and plant area) deteriorated depending on water availability. This was also the case for the root system development displayed by root dry weight, total length, and surface area. It is the first time the OJIP transient has been evaluated after the application of A. nodosum for drought-stressed plants. Chlorophyll fluorescence parameters showed that the photosynthetic apparatus was more stressed when A. nodosum was applied, especially in the harshest conditions (i.e., 50% field capacity). Overall, the silicon-based biostimulant failed to demonstrate drought-mitigating potential compared to the non-treated counterparts. On the other hand, A. nodosum alleviated the negative effects of water deficit, especially in the harshest conditions
The Use of High-Quality Watermelon Seedlings Is Prerequisite to Limit the Transplanting Shock and Achieve Yield Earliness
No full textOne of the most important crops of the Mediterranean, watermelon (Citrullus lanatus), is almost exclusively established through seedlings. For many years, agronomists, nurseries, and farmers have aimed to produce and use high-quality seedlings for better growth in the field. However, seedling quality has not been examined as to what defines the subsequent plant, flower, and fruit development, and to what extent. Our aim was to test whether different seedling qualities labeled as “Optimum”, “Acceptable”, or “Not Acceptable” for cultivation actually perform variably in terms of vegetative, flowering, and fruit development, as well as fruit quality after a full growing cycle in the field. Vegetative growth (stem diameter, plant area, and leaf number) was evaluated until flowering and was enhanced for Optimum plants. The flowering of Not Acceptable plants started two days later, while Optimum plants retained a greater number of female flowers throughout the two-week blooming evaluation. Most importantly, Optimum plants developed mature fruits four and six days faster than the Acceptable and Not Acceptable ones, respectively, showing considerable yield earliness. The photosynthetic mechanism, as well as fruit morphology and phytochemical content, were not affected by quality categories. Overall, indeed it is important to use high-quality seedlings to achieve yield earliness of watermelon fruits
Ascophyllum nodosum and Silicon-Based Biostimulants Differentially Affect the Physiology and Growth of Watermelon Transplants under Abiotic Stress Factors: The Case of Salinity
No full textSalinization of cultivated soils is a global phenomenon mainly caused by agricultural practices and deteriorates plant production. Biostimulants are products which can be applied exogenously to enhance the plants’ defense mechanism and improve their developmental characteristics, also under abiotic stresses. We studied the potential of two biostimulants, Ascophyllum nodosum (Asc) seaweed and a silicon-based (Si), to alleviate the saline conditions endured by watermelon transplants. Three salinity (0 mM, 50 mM, and 100 mM NaCl) treatments were applied in watermelon seedlings transplanted in pots, while the two biostimulants were sprayed in the foliar in the beginning of the experiment. Relative water content was improved by Asc in the high salinity level. The plant area, leaf number, and shoot dry weight deteriorated in relation to the salinity level. However, the root system (total root length and surface area) was enhanced by 50 mM salt, as well as Asc in some cases. The OJIP transient of the photosynthetic apparatus was also evaluated. Some OJIP parameters diminished in the high salinity level after Asc application. It is concluded that after salt stress Asc provoked a positive phenotypic response, while Si did not alleviate the salinity stress of transplanted watermelon
Impact of Light on Horticultural Crops
No full textLight is an essential factor for the growth and quality of horticultural plants and its effects depend upon parameters such as duration, intensity and quality [...
Postharvest physiology and quality of fresh-cut rocket (Eruca sativa Mill.) and peach (Prunus persica L.)
No full textA new category of horticultural products, this of fresh-cut fruit and vegetables has arisen the last years. During their processing, many physiological and biochemical alterations are noticed such as: a) increased ethylene and CO2 production, b) increased transpiration, c) membrane deterioration and d) secondary metabolite production, which lead to browning of the cut surfaces, yellowing, softening etc. and induce faster quality loss of the fresh-cut fruit compared to the intact ones. The purpose of this thesis was to study the postharvest physiology of fresh-cut rocket and peach and also to investigate the various factors that affect their quality. In particular, the factors that were studied in rocket were: a) the leaf age, b) the degree of wounding that was determined by the different leaf size, c) the storage temperature, d) the presence of ethylene in the storage environment, e) treatment with 1-MCP, f) treatment with 6-BA and g) the heat treatment. On the other hand, the factors that were studied in the peach were: a) the cultivar, b) the degree of wounding that was determined by the cutting and/or peeling, c) treatment with 1-MCP, d) treatment with various chemical compounds (citric acid, ascorbic acid, calcium chloride and oxalic acid) and e) heat treatment. The results showed that chlorophyll degradation was the most important postharvest alteration observed in fresh-cut rocket that resulted in leaf yellowing. During harvest, in young leaves the highest ethylene and CO2 production were recorded. In addition, they had more soluble solids content (SSC) and total soluble phenols but less nitrates compared to the fully expanded and mature leaves. During storage, in young leaves a significantly higher ethylene production was noticed, but not greater chlorophyll losses were observed after 10 days of storage at 10oC compared to the fully expanded and mature leaves. The degree of wounding, that was determined by the different leaf size (1 particle of 14 cm or 2 particles of 7 cm each or 4 particles of 3.5 cm each) had no effect on the CO2 and ethylene production during storage. After 14 days at 8oC in MAP, no differences between treatments were observed regarding color, chlorophyll content and chemical composition. Chlorophyll degradation in rocket leaves was prevented significantly during storage in low temperatures. Specifically, the shelf-life of the leaves that were stored at 0oC was 16 days, but it was reduced (3 days) in the leaves that were stored at 5oC. The quality of the leaves that were stored at 10oC was deteriorated very quickly (intense yellow colour) and their shelf-life was only 8 days. The ethylene presence (1 μl l-1) in the storage environment accelerated significantly the rocket yellowing compared to the leaves that were stored in air and reduced the shelf-life (at 10oC) from 10 to 8 days. Exposure of the leaves before storage to 1-MCP (0.5 μL L-1 for 4 hours at 10oC), limited the yellowing effect of the ethylene. Dipping of rocket leaves to a 6-BA solution (10 μl l-1) for 30 sec reduced the CO2 production (by 33%) and limited the chlorophyll deterioration (by 53%) compared to the control. In contrast, it had no significant effect on their chemical composition (SSC, ascorbic acid, nitrates, phenols and the total antioxidants). Heat treatment of leaves (dipping in water temperature of 50oC for 30 sec) reduced significantly the chlorophyll loss from 36% to 7%, after being stored in MAP at 8oC for 10 days. In addition, the heat treatment reduced the weight loss compared to the control from 3.4% to 2.2%, without affecting the chemical composition (SSC, ascorbic acid, nitrates, phenols and the total antioxidants).Τα νωπά τεμαχισμένα φρούτα και λαχανικά αποτελούν μια νέα κατηγορία οπωροκηπευτικών προϊόντων, κατά την προετοιμασία των οποίων παρατηρούνται πολλές φυσιολογικές και βιοχημικές μεταβολές, με κυριότερες την αυξημένη παραγωγή αιθυλενίου και διοξειδίου του άνθρακα (CO2), την αυξημένη διαπνοή, τη καταστροφή των μεμβρανών και την παραγωγή δευτερογενών μεταβολιτών, που προκαλούν καφέτιασμα στις επιφάνειες τομής, κιτρίνισμα, μαλάκωμα κ.ά. Άμεση συνέπεια των παραπάνω είναι η ταχύτερη υποβάθμιση της ποιότητάς τους, σε σχέση με τα ακέραια προϊόντα. Σκοπός της διατριβής ήταν η μελέτη της μετασυλλεκτικής φυσιολογίας των νωπών τεμαχισμένων προϊόντων ρόκας και ροδάκινου και η διερεύνηση της επίδρασης διαφόρων παραγόντων στην ποιότητά τους. Ειδικότερα, οι παράγοντες που μελετήθηκαν στη ρόκα ήταν η ηλικία των φύλλων κατά τη συγκομιδή, ο βαθμός τραυματισμού που καθορίστηκε από το διαφορετικό μέγεθος των τεμαχίων των φύλλων, η θερμοκρασία συντήρησης, η παρουσία αιθυλενίου στο περιβάλλον συντήρησης, το 1-MCP, η 6-BA και η θερμική μεταχείριση, ενώ στο ροδάκινο μελετήθηκαν η ποικιλία, ο βαθμός τραυματισμού που καθορίστηκε από το τεμαχισμό ή/και την αποφλοίωση, το 1-MCP, διάφορες χημικές ουσίες (κιτρικό οξύ, ασκορβικό οξύ, χλωριούχο ασβέστιο και οξαλικό οξύ) και η θερμική μεταχείριση. Τα αποτελέσματα έδειξαν ότι η σημαντικότερη μεταβολή που παρατηρήθηκε μετασυλλεκτικά στη νωπή τεμαχισμένη ρόκα ήταν η διάσπαση της χλωροφύλλης, που είχε ως αποτέλεσμα το κιτρίνισμα των φύλλων. Κατά τη συγκομιδή, παρατηρήθηκε ότι τα νεαρά φύλλα είχαν την υψηλότερη παραγωγή CO2 και αιθυλενίου, ενώ περιείχαν περισσότερα διαλυτά στερεά συστατικά (ΔΣΣ) και ολικές διαλυτές φαινόλες και λιγότερα νιτρικά από τα πλήρως ανεπτυγμένα και τα ώριμα φύλλα. Στη διάρκεια της συντήρησης καταγράφηκε σημαντικά υψηλότερη παραγωγή αιθυλενίου στα νεαρά φύλλα, χωρίς ωστόσο να παρατηρηθούν μεγαλύτερες απώλειες σε χλωροφύλλη μετά από συντήρηση 10 ημερών στους 10oC, σε σχέση με τα πλήρως ανεπτυγμένα και ώριμα φύλλα. Ο βαθμός τραυματισμού που καθορίστηκε από το διαφορετικό μέγεθος των τεμαχίων των φύλλων (ολόκληρο φύλλο των 14 cm ή δύο τεμάχια των 7 cm ή 4 των 3,5 cm) δεν επηρέασε την παραγωγή CO2 και αιθυλενίου κατά τη διάρκεια της συντήρησης στους 8οC για 14 ημέρες, ούτε το χρώμα, την περιεκτικότητα σε χλωροφύλλη και τη σύσταση (ΔΣΣ, ασκορβικό οξύ, νιτρικά, ολικές διαλυτές φαινόλες και συνολική αντιοξειδωτική ικανότητα μετά από 14 ημέρες στους 8oC σε συνθήκες τροποποιημένης ατμόσφαιρας (ΤΑ). Η διάσπαση της χλωροφύλλης των φύλλων επιβραδύνθηκε σημαντικά κατά τη συντήρηση στις χαμηλότερες θερμοκρασίες, με αποτέλεσμα μέγιστη διάρκεια ζωής στο ράφι στους 0oC να ανέρχεται στις 16 ημέρες, ενώ στους 5oC και 10oC τα αντίστοιχα διαστήματα ήταν 13 και 8 ημέρες. Η παρουσία αιθυλενίου (1 μl l-1) στο περιβάλλον συντήρησης (10oC) επιτάχυνε σημαντικά το κιτρίνισμα των φύλλων, μειώνοντας τη μέγιστη διάρκεια διατήρησης αποδεκτού χρώματος από 10 σε 8 ημέρες. Η έκθεση των φύλλων για 4 ώρες στους 10oC σε 0,5 μl l-1 1-MCP πριν τη συντήρηση, απέτρεψε το κιτρίνισμα που προκλήθηκε από την παρουσία του αιθυλενίου στο περιβάλλον συντήρησης. Η εμβάπτιση φύλλων σε υδατικό διάλυμα 10 μl l-1 6-BA για 30 sec μείωσε την παραγωγή CO2 κατά 33% και περιόρισε τη διάσπαση της χλωροφύλλης κατά 53% σε σχέση με το μάρτυρα, ενώ δεν επηρέασε σημαντικά τη σύστασή τους (ΔΣΣ, ασκορβικό οξύ, νιτρικά, ολικές διαλυτές φαινόλες και συνολική αντιοξειδωτική ικανότητα). Η θερμική μεταχείριση (εμβάπτιση των φύλλων σε νερό θερμοκρασίας 50oC για 30 sec) περιόρισε σημαντικά την απώλεια χλωροφύλλης από 36 σε 7%, μετά από συντήρηση σε ΤΑ στους 8oC για 10 ημέρες. Επιπλέον, η θερμική μεταχείριση μείωσε την απώλεια βάρους των φύλλων σε σχέση με το μάρτυρα από 3,4 σε 2,2%, χωρίς να επηρεάσει τη σύσταση (ΔΣΣ, ασκορβικό οξύ, νιτρικά, ολικές διαλυτές φαινόλες και συνολική αντιοξειδωτική ικανότητα)
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