Papers by Antonios Petridis
Acta horticulturae, May 1, 2012
The effects of NaCl salinity on growth, leaf water potential (Ψ w ), CO 2 assimilation rate (P n ... more The effects of NaCl salinity on growth, leaf water potential (Ψ w ), CO 2 assimilation rate (P n ), chlorophyll (a+b) concentration and fluorescence, total carbohydrates, proline concentration and Na + and Cl -concentration as indices of salt tolerance of four olive cultivars ('Zard', 'Ascolana', 'Koroneiki' and 'Arbequina') were studied. The plants were grown in black, plastic bags containing sand-perlite mixture (1:1) for five months and were irrigated with half strength Hoagland's nutrient solution containing 0, 25, 50, 75, 100 and 125 mM NaCl. The results indicated significant differences in salt tolerance among the four olive cultivars. 'Zard' was the least tolerant, showing symptoms of chlorosis and necrosis the fourth month of the experiment in the two higher NaCl concentrations. 'Koroneiki' showed toxicity symptoms one month later and the other two cultivars did not show any symptoms during the five months duration of the experiment with the 'Ascolana' being slightly superior to 'Arbequina'. After five months from the beginning of the treatments 'Zard' showed a 40-45% decrease in shoot length growth compared with the control, 'Koroneiki' 23,3-40%, 'Arbequina' 21,4-35% and 'Ascolana' 22,3-29,6%. At the concentration of 125 mM NaCl, 'Zard' showed a decrease in photosynthesis, transpiration, leaf water potential and chlorophyll content of 59, 75, 138 and 58% respectively. The carbohydrate content remained at the same level as the control, while proline content increased by 58%. In 'Ascolana' photosynthesis and leaf water potential decreased by 35 and 166%, respectively, while all the other physiological parameters increased. The corresponding parameters in the two other cultivars had intermediate values. An elevated accumulation of Na + and Cl -in leaves was recorded by increasing the NaCl concentration in solution in all cultivars with 'Zard' showing the higher one.
BioTech
Grey mould, caused by Botrytis cinerea and other Botrytis spp., is a major cause of fruit rot in ... more Grey mould, caused by Botrytis cinerea and other Botrytis spp., is a major cause of fruit rot in strawberries and other fruit crops worldwide. Repeated fungicide applications are essential in order to secure harvests. However, resistance to all currently registered single-site fungicides is widespread. The rising importance of strains with multiple resistance to most or all fungicides is of particular concern. These strains may be introduced into fields via contaminated nursery plants and/or by immigration from adjacent plots. On the basis of research conducted in northern German and Danish strawberry production, a concept to manage fungicide resistance under northern European conditions has been developed and put into regional strawberry production practice. This principally includes the testing of nursery plants for fungicide-resistant Botrytis strains prior to planting; the restricted and specific use of fungicides at flowering in the production fields, taking account of the resi...
In the present dissertation, the effect of various factors on oleuropein concentration in differe... more In the present dissertation, the effect of various factors on oleuropein concentration in different tissues or organs of the olive tree (Olea europaea L.) was studied. These factors were two abiotic stress conditions (salinity and water stress), fruit growth and ripening, two training systems, leaf canopy position and the genotype (cultivar). The aim of the first experiment was to determine the phenolic status (total phenol content, oleuropein and hydroxytyrosol) and antioxidant activity of four olive cultivars under saline conditions in two different plant parts (leaves and root). We also tested the possible relationship between oleuropein and glucose, since the latter compound is a part of the former molecule and accumulates under saline conditions. The data indicate that salinity stimulated the biosynthesis of phenols and oleuropein, especially in leaves, whereas the hydroxytyrosol concentration was either negatively or not affected by the salt stress. Oleuropein was the main phe...
Journal of the Science of Food and Agriculture, 2020
BACKGROUNDIn maritime growing environments, blueberry yield often exhibits excessive season‐to‐se... more BACKGROUNDIn maritime growing environments, blueberry yield often exhibits excessive season‐to‐season variation, associated with poorly adapted photosynthetic responses to low light conditions. It is therefore necessary to develop methods that stabilise yield while maintaining or improving fruit quality. Here, we placed reflective mulch alongside plants at the early green fruit stage, to test the hypothesis that increasing the available seasonal light integral could enhance blueberry yield. We further determined several quality characteristics to ensure fruit marketability.RESULTSPlacement of mulch alongside plants reflected up to five times more light compared with bare ground, enhancing the amount of light reaching the canopy. This led to an adaptive increase of light saturated maximal photosynthetic rate of mulch‐treated plants, resulting in a twofold increase in yield compared with control plants. Analysis of fruit quality characteristics showed that total soluble solids, sugars...
International Journal of Agriculture Innovations and Research, 2014
Cherry cracking due to rain is the major problem for cherry cultivation. Several methods have bee... more Cherry cracking due to rain is the major problem for cherry cultivation. Several methods have been proposed for alleviating this problem, including the use of rain protective coverings. The aim of this research was to study the effect of rain protective covering on fruit cracking, fruit quality and photosynthetic parameters of four sweet cherry cultivars. The experiments were conducted during three successive years. Half of a commercial cherry orchard was covered by high density polyethylene plastics, whereas the other half remained uncovered (control). The results showed that the covering had no affect on the productivity and mean fruit weight in all cultivars, except for ‘Early Lory’ which had higher values in 2009. The cracking percentage of all cultivars was significantly lower in covered trees than the controls, resulting in a positive tendency on marketable yield. In 2010, total antioxidant activity was higher in the covered fruits of ‘Ferrovia’, ‘Early Star’ and ‘Van’ compare...
Agronomy, 2021
Producing food via vertical farming (VF) is an efficient method since it requires less space with... more Producing food via vertical farming (VF) is an efficient method since it requires less space with increased yield per unit area. Such a system can assist in solving major food-shortage problems since it presents a higher crop yield per unit area compared to conventional farming. Thus, VF can be seen as a production method that can cope with the challenge of the constantly growing population, making it also possible to cultivate crops in regions with adverse climate conditions. However, the public might be concerned about the sustainability of VF systems since plants are produced in an unconventional setting. Therefore, there is a need to consider and evaluate the consumers’ acceptance of VF. The particular study attempts to both analyse consumer acceptance of VF in the Nordic areas and offer insights into VF acceptance among young customers in a comparative analysis. The results indicated that VF is not widely accepted by young Nordic consumers. The concept of sustainability is one ...
Environmental and Experimental Botany, 2020
In some growing environments blueberry (Vaccimium corymbosum L.) yields exhibit excessive annual ... more In some growing environments blueberry (Vaccimium corymbosum L.) yields exhibit excessive annual variation associated with poor photosynthetic performance. The purpose of this study was to determine how photosynthesis may be affected by demand and to define the mechanisms underpinning photosynthetic plasticity. Manipulation of source-sink ratios revealed that yields were maintained following 50 % defoliation. This was associated with an adaptive increase in photosynthetic capacity mediated via changes in stomatal physiology, photosynthetic electron transport and CO 2 assimilation. Transcripts encoding enzymes of the Calvin-Benson cycle including the Rubisco large subunit, Rubisco activase, phosphoribulokinase and plastid-localised glyceraldehyde phosphate dehydrogenase 3 were more abundant in leaves from partially defoliated plants relative to control plants. Short-term 13 CO 2 labelling experiments suggested that partial defoliation did not incur an assimilation penalty although the accumulation of sugars and starch in some organs was reduced. Metabolite profiles of leaves from partially defoliated plants exhibited some differences from those of control leaves, however, no changes in the diurnal content of leaf sugar and starch were observed between treatments. The data highlights the mechanisms by which blueberry leaves adapt to increased demand and demonstrate that photosynthetic plasticity can compensate for significant loss of the photosynthetic area.
Journal of Experimental Botany, 2018
Published evidence indicates that nearly 60% of blueberry-producing countries experience yield in... more Published evidence indicates that nearly 60% of blueberry-producing countries experience yield instability. Yield is a complex trait determined by genetic and environmental factors. Here, using physiological and biochemical approaches, we tested the hypothesis that yield instability results from year-to-year environmental variation that limits carbon assimilation, storage and partitioning. The data indicate that fruit development depends primarily on the daily production of non-structural carbohydrates by leaves, and there is no accumulation of a starch buffer to allow continuous ripening under conditions limiting for photosynthesis. Photosynthesis was saturated at moderate light irradiance and this was mainly due to stomatal and biochemical limitations. In a dynamic light environment, photosynthesis was further limited by slow stomatal response to increasing light. Finally, labelling with 13 CO 2 at specific stages of fruit development revealed a relatively even distribution of newly assimilated carbon between stems, roots and fruits, suggesting that the fruit is not a strong sink. We conclude that a significant component of yield variability results from limitations in photosynthetic efficiency that are compounded by an inability to accumulate starch reserves in blueberry storage tissues in a typical northern European environment. This work informs techniques for improving agronomic management and indicates key traits required for yield stability in such environments.
HortScience, 2009
In Greece, the dominant kiwifruit cv. since 1973 has been Hayward with a total annual fruit produ... more In Greece, the dominant kiwifruit cv. since 1973 has been Hayward with a total annual fruit production of 40,000 t and an acreage of 4400 ha (FAO, 2004). However, selection among 15,000 seedlings originated from open-pollinated 'Hayward' plants in northern Greece in 1989 by the farmer Christos Tsechelidis, resulting in the cv. Tsechelidis. Based on molecular analysis using small satellite DNA markers, the two genotypes ('Hayward', 'Tsechelidis') were considered to be different because they presented polymorphism in at least eight alleles. For example, the following primers/alleles, 97-411, 96-037b, 96-034, and 96-092, were present in 'Tsechelidis' and absent in 'Hayward'. Also, 96-037a and 97-406 were present in 'Hayward' and absent in 'Tsechelidis' (Ilanidis et al., 2006). Kiwifruit [Actinidia deliciosa (A. chev.) C.F. Liang et A.R. Ferguson var. deliciosa] is a deciduous vine indigenous to the mountainous regions of central and southwestern China. Approximately 70% of kiwi's world production is from China, Italy, Chile, and New Zealand (FAO, 2004). Kiwifruit consumption is increasing each year in central Europe, indicating an expanding market. The majority of the commercial plantings worldwide are of the cv. Hayward selected in New Zealand %70 years ago (Ferguson and Lay Yee, 1983).
HortScience, 2010
The effect of various commercial calcium (Ca) -containing products applied as preharvest foliar s... more The effect of various commercial calcium (Ca) -containing products applied as preharvest foliar sprays on several fruit quality attributes and nutritional status of the kiwifruit cultivar Tsechelidis for a 2-year period is reported. Foliar application of all Ca products plus boron did not affect mean fruit weight compared with the control. During the first year, the highest flesh firmness was measured after application of the Ca-containing products Acid CaLMg and Calfruit plus Qualyfruit. During the second year, the highest flesh firmness was measured after application of the product Acid CaLMg. The highest ascorbic acid content and total antioxidant power were recorded after application of the product Chelan CaP. Foliar application of Power-Ca resulted in an increase of Ca concentration of leaves compared with the control for the first year. During the second year, all Ca-containing products increased Ca concentration of leaves compared with the control. Foliar application of Calfr...
HortScience, 2010
The antioxidant activities (μmol ascorbic acid equivalent/g fresh weight) of the edible part of f... more The antioxidant activities (μmol ascorbic acid equivalent/g fresh weight) of the edible part of fruits grown in northern Greece were determined using the ferric-reducing antioxidant power (FRAP) assay. Differences were observed among species as well as cultivars of the same species. Cornelian cherry had the highest FRAP value followed by jujube. Cherries, black grapes, and blackberry showed high activity followed by pears, persimmons, plums, peaches, white grapes, pomegranates, apples, nectarines, kiwifruits, quinces, figs, and apricots.
HortScience, 2009
Additional index words. cultivar description, fruit breeding, Pyrus communis 'Kalliopi' is a mid-... more Additional index words. cultivar description, fruit breeding, Pyrus communis 'Kalliopi' is a mid-to late July maturing pear cultivar originating from a cross between the local Greek pear cultivars Kristali and Kontoula. Fruit are obtuse-pyriform to nearly turbinate with equatorial diameter %50 mm, fruit length %45 mm, and fruit weight %121 g. Productivity of 'Kalliopi' was lower than 'Coscia'; however, yield efficiency of the two cultivars was not different. Total soluble solids and firmness of 'Kalliopi' were higher than 'Coscia', whereas total titratable acidity was not different among the cultivars. The flesh is yellow-white, juicy, sweet-flavorful, and fine-grained with very few stone cells (scleroids). The skin is green, blushed red with sun exposure, smooth, free of russeting, and has no tendency to become waxy in storage. Fruit ripens on the tree in mid-to late July, and a selective harvest of three picks is required. The fruit flavor is sweet. After harvest, fruits can be kept at room temperature for %1 week or they can be refrigerated (1°C) for 1 month after which time internal breakdown tends to occur.
HortScience, 2012
The chemical and biochemical composition of olives relies on some agronomical factors, one of whi... more The chemical and biochemical composition of olives relies on some agronomical factors, one of which is the cultivar. In this study, fruits and leaves of 11 Greek olive cultivars were examined concerning their phenol and oleuropein concentrations. Fruit antioxidant activity was determined as well. The obtained results showed that significant differences existed among cultivars regardless of the tissue or the measured parameter. In general, leaves had higher total phenol and oleuropein concentrations than fruits. Finally, the highest oleuropein concentration in fruits was recorded in ‘Pikrolia Kerkiras’ followed by ‘Romeiki’, ‘Megaritiki’, ‘Kothreiki’, and ‘Kalamon’. These cultivars may constitute the raw material in the industrial production of oleuropein.
HortScience, 2011
Cornelian cherry is a minor fruit species that deserves some attention mainly as a result of its ... more Cornelian cherry is a minor fruit species that deserves some attention mainly as a result of its economic potential and environmental importance of its cultivation. 'Ntoulia 1' and 'Ntoulia 2' are two new Greek cornelian cherry cultivars, whereas 'Electra' and 'Naoussa' are new selected clones. The experiment was conducted in northern Greece for 2 consecutive years.
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Papers by Antonios Petridis