Foliar calcium effects on quality and primary and secondary metabolites of white-fleshed ‘Lemonato’ peaches

‘Lemonato’ is a Greek peach melting-flesh white-flesh cultivar with high nutritional value highly appreciated by the consumers. This study aimed to evaluate the effect of pre-harvest foliar calcium application on fruit quality, primary metabolite profile, antioxidant activity, total phenolic content, and phenolic profile of the ‘Lemonato’ peach, clone ‘Stamatis’. The experiment was conducted for two years, 2019 and 2020, in two commercial orchards at Kato Lehonia and Agios Vlasios regions, central Greece, where the ‘Lemonato’ clone ‘Stamatis’ is traditionally cultivated. The treatments were organic calcium (Ca), calcium–silicate in nanoparticles (Ca–Si), and calcium chloride (CaCl2). Foliar application of the different Ca formulations, commonly used as a horticultural practice, were not effective at improving the fruit quality characteristics in this clone, which is characterized by fruit softening during ripening. The study revealed the sugars and organic acid composition and phenolic profile of the ‘Lemonato’ peach, clone ‘Stamatis’. Peach fruit quality, primary metabolites, and phenolic compounds of the two orchards showed a different response to organic Ca and Ca–Si, indicating that genetic or environmental factors may also be involved. A higher concentration of organic Ca and CaCl2 increased the peach fruit phenolic compounds content and the total antioxidant activity, improving the fruit nutritional qualit

Kaolin particle film on peach leaf physiology

Hot summers, typical of the Mediterranean region, negatively affect temperate zone tree productivity. Kaolin particle films are used to alleviate heat stress under these conditions. We investigated the effect of kaolin particle film on peach leaf physiological characteristics and functions in central Greece. Kaolin particle film was applied periodically from early June to early August 2011 on 'Royal Glory' peach trees. Leaf temperature and available radiation as well as various leaf parameters and functions were measured from June until late September. The presence of kaolin on leaf surfaces reduced incident radiation and leaf temperature, and increased reflected radiation compared to control leaves. At the beginning of kaolin application in June, leaves treated with kaolin had similar leaf functions to control leaves. From July until late September, even after rains removed most of kaolin in September, peach leaves treated with kaolin had higher stomatal conductance, transpiration and photosynthetic rates than control leaves. In addition, from mid-July until late September leaves treated with kaolin had decreased chlorophyll (a, b and total) concentration per m2 leaf surface compared to control leaves, while specific leaf area remained unchanged due to kaolin presence. It appears that the reduction of incident radiation and leaf temperature in the presence of kaolin reduced heat stress, which, in turn, increased leaf productivity in this early to mid-season ripening peach cultivar. © 2015 ISHS

Effects of particulate matter contamination on peach leaf physiological functions

During the summer, precipitation events occur rarely in the Mediterranean region. This results in cement kiln dust deposition on crops grown around cement factories or soil dust deposition on crops grown next to unpaved farm roads. The purpose of this study was to investigate the effects of particulate matter contamination from cement kiln and soil dust on peach leaf physiological characteristics and functions. Cement kiln dust and soil dust were applied periodically during the summer 2009 in 'Royal Glory' peach trees (fruit harvested early July) located away from contamination sources. Dust accumulation on treated peach leaves and various leaf physiological parameters were measured periodically over the summer period until late September. Specific leaf mass increased and chlorophyll content decreased after harvest and remained unchanged over the summer due to summer heat stress or, most probably, due to low 'sink' demand. Leaf gas exchange functions significantly decreased in June due probably to soil drying and transition of the functioning root system from the whole soil profile to the drip irrigated areas only. Contaminated leaves progressively accumulated soil and cement dust over the summer. This contamination resulted in increased specific leaf mass and decreased leaf chlorophyll content compared to leaves from control plants (uncontaminated). Peach leaves dusted with soil and cement had lower stomatal conductance and transpiration and photosynthetic rates than control leaves throughout the summer period. In May, at the beginning of particulate matter application, and in late September, when rains had removed substantial part of the deposited dust, leaf functions were similar in all treatments. The presence of cement or soil dust contamination did not cause any macroscopic toxicity to peach leaves. But the reduction in leaf productivity may have negative consequences on yield and, possibly, fruit quality, especially for the midseason and late ripening peach cultivars

Nutrient inputs and outputs in commercial clingstone peach orchards in Greece based on conventional or sustainable fertilization practices

Clingstone peach production is important in Greece as large amounts of processed peaches are being exported throughout the world. Fertilization of peach farms is still conducted empirically with substantial amounts of N, P and K applied in late winter with basic composite fertilizers rarely followed by additional N and K or Ca applications in spring and summer. A more sustainable fertilization program was followed using <50% N, minor quantities of P, and similar or higher quantities of K than that applied with the local regime and with a different schedule compared to local practices in a number of farms and commonly grown cultivars. Inorganic nutrients were measured in fruits and prunings after two years of sustainable fertilization practices. Fruit yield and prunings volume were measured. The macronutrient inputs in the sustainable program were (in kg/ha): in 2019 <70 N, <30 P2O5, <100 K2O, and in 2020 <85 N, <40 P2O5, <155 K2O. Outputs with fruit normalized for 40 Mg ha-1 (most farms during the two years had lower yield) in 2020 were (in kg ha-1): <50 N, <11 P2O5, <4.3 CaO, <4.4 MgO, <80 K2O. Outputs with prunings in 2020 were (in kg ha-1): <25 N, <4 P2O5, <30 CaO, <3 MgO, <11 K2O. The balance between inputs and outputs was improved using the sustainable fertilization program, while fertilizer cost was variably affected and the possible environmental and economic burden due to nutrient losses decreased. © 2022 International Society for Horticultural Science. All rights reserved

The effect of postharvest application of O3 and 1-MCP on 'Red Chief' apple quality during prolonged air cold storage

The effects of postharvest application of 1-MCP and air storage in the presence of low O3 concentration on 'Red Chief' apple fruit quality were studied during prolonged storage. Apple fruit were harvested from two commercial orchards from 300 and 700 m elevation in the Zagora region, central Greece, during September 2012. The next day, the fruit were treated or not with 600 nl L-1 1-MCP and stored at two commercial rooms at 0°C (90-95% RH) with or without 50-60 nl L-1 O3. Apple quality was evaluated at harvest and after 2.5, 5 and 7.5 months immediately after storage and after 7 days shelf-life (20-22°C, 50-60% RH). Quality evaluation included skin color, flesh firmness, juice soluble solids content (SSC) and titratable acidity, and superficial scald incidence. Apples from the orchard at high elevation had darker redder skin color were firmer, and had lower SSC, acidity and scald incidence at harvest and during storage, than the apples from the orchard at low elevation. Fruit treated with 1-MCP kept their high quality with minor scald incidence and firmness loss even after 7.5 months cold storage in the presence or not of O3. Fruit stored with low O3 without 1-MCP treatment at harvest were of similar quality to control fruit, but had higher scald incidence. It is concluded that 1-MCP treatment at harvest, satisfactorily maintained apple fruit quality without the addition of O3 in air cold storage, while fruit not treated with 1-MCP should not be stored in the presence of low O3 concentration

Effects of Alternative Fertilization and Irrigation Practices on the Energy Use and Carbon Footprint of Canning Peach Orchards

Throughout peach orchards in Greece, plant protection, fertilization and irrigation are often conducted empirically, negatively affecting energy use efficiency and greenhouse gas emissions (GHG emissions). The aim of this study was to apply alternative fertilization and irrigation practices in canning peach orchards to improve nutrient and irrigation water management and to assess yield, energy input–output and the carbon footprint of the alternative cultivation practices for three important clingstone cultivars of different ripening periods. Energy use analysis revealed that the cultivation practice with the highest energy use was almost always irrigation, followed by fertilization, plant protection, weed control and pruning. Electricity, fuels, fertilizers and machinery presented the highest energy requirements. Alternative fertilization, in combination with deficit irrigation (DI), was more energy efficient compared to farmers’ practices in all cultivars based on energy use efficiency, energy productivity and specific energy. Irrigation was the cultivation practice with the highest impact on GHG emissions due to electricity and, secondly, to fuel consumption. Alternative fertilization and DI decreased the intensity (kg CO2eq kg−1) of the emitted GHG compared to farmers’ practices. In conclusion, alternative fertilization and irrigation practices improved energy use efficiency and decreased the carbon footprint of the canning peach orchards by improving yield and decreasing fertilizer and irrigation water input. © 2022 by the authors

The effect of postharvest application of O<inf>3</inf> and 1-MCP on 'Red Chief' apple quality during prolonged air cold storage

The effects of postharvest application of 1-MCP and air storage in the presence of low O3 concentration on 'Red Chief' apple fruit quality were studied during prolonged storage. Apple fruit were harvested from two commercial orchards from 300 and 700 m elevation in the Zagora region, central Greece, during September 2012. The next day, the fruit were treated or not with 600 nl L-1 1-MCP and stored at two commercial rooms at 0°C (90-95% RH) with or without 50-60 nl L-1 O3. Apple quality was evaluated at harvest and after 2.5, 5 and 7.5 months immediately after storage and after 7 days shelf-life (20-22°C, 50-60% RH). Quality evaluation included skin color, flesh firmness, juice soluble solids content (SSC) and titratable acidity, and superficial scald incidence. Apples from the orchard at high elevation had darker redder skin color were firmer, and had lower SSC, acidity and scald incidence at harvest and during storage, than the apples from the orchard at low elevation. Fruit treated with 1-MCP kept their high quality with minor scald incidence and firmness loss even after 7.5 months cold storage in the presence or not of O3. Fruit stored with low O3 without 1-MCP treatment at harvest were of similar quality to control fruit, but had higher scald incidence. It is concluded that 1-MCP treatment at harvest, satisfactorily maintained apple fruit quality without the addition of O3 in air cold storage, while fruit not treated with 1-MCP should not be stored in the presence of low O3 concentration

Alternative practices to improve ‘Firiki’ apple cultivation

‘Firiki’ is a local to central Greece apple cultivar approved as protected designation of origin based on its history and high quality. Its cultivation is not expanding due to its major drawbacks: alternate bearing, strong vegetative growth and bruising susceptibility. Trials were performed in two commercial orchards to manage vegetative growth and increase bruising resistance. Fruiting trees were sprayed 12 days after full bloom with Prohexadione-Ca (Pro-Ca) or repeatedly with a commercial product containing calcium silicate (CaSi) in nanoparticles in combination with summer pruning. Branch girdling was performed around 15 days after full bloom. Leaf, and shoot characteristics were measured in June and September, and fruit quality was evaluated at commercial maturity early October. Pro-Ca resulted in reduced shoot growth and nodal length, negatively affected leaf characteristics (specific leaf mass, chlorophyll content), shoot dry matter, and fruit mass, with minor effects on fruit quality at commercial harvest. Girdling also resulted in reduced shoot growth and leaf chlorophyll content, but increased shoot dry matter, fruit mass and fruit quality (except of decreased flesh firmness). CaSi did not result in a similar pattern on all characteristics measured in the two orchards evaluated, but even more, it was found to accelerate flesh bruising appearance compared to control. Girdling seems a promising method to manage vegetative growth and fruit quality in ‘Firiki’ apple, but alternative methods should be tested to improve fruit bruising resistance. © 2021 International Society for Horticultural Science. All rights reserved

Effects of foliar calcium applications and maturity stage on ‘Lemonato’ peach fruit quality and bruising severity

‘Lemonato’ peach is a traditional Greek series of clones particularly valued by the consumers because of its high fruit quality, flavor and aroma. The main problem of ‘Lemonato’ peach is flesh softening during ripening and the susceptibility of ripe fruit to bruising. Our hypothesis was that harvesting the fruit earlier than its commercial maturity could reduce fruit quality losses during postharvest handling. Secondly, innovative Ca formulations could reduce bruising incidence by strengthening cell walls and reducing flesh softening. In this work, two clones of ‘Lemonato’ peach (a mid-season ‘Andrea’ and a late-season ‘Mytera’) were used in order to study the effects of maturity stage, such as early harvest (EH) and commercial maturity (CM) on fruit quality. Moreover, the influence of foliar Ca applications on fruit quality with two formulations containing calcium-silicate in nanoparticles (CaSi) and organic Ca (OrCa) were also tested. Estimated fruit quality parameters included total phenols content (TPC), total antioxidant activity (TAA), and bruising severity. Compared to ‘Andrea’ clone, ‘Mytera’ fruit had better quality traits, higher TPC and TAA in both maturity stages, whereas at EH it had fruit mass similar to ‘Andrea’ and higher browning index (BI) fruit because of differences in tree fruit load. In all treatments and clones, CM fruit improved organoleptic characteristics compared to EH fruit. ‘Andreas’ fruit harvested at CM had higher fruit mass and significantly softer flesh than EH fruit without any effect from Ca applications. ‘Mytera’ fruit at CM had higher TPC and TAA than EH fruit in all treatments. Flesh browning caused by mechanical bruising increased with time mainly during the first 10 min after bruising in all treatments and maturity stages of both clones. Ca-treated fruit had slightly increased TPC and TAA, except of CM OrCa ‘Mytera’ fruit, which had lower quality parameters compared to control. Hovewer, this was not associated with BI. In both ‘Lemonato’ clones, Ca applications did not improve flesh firmness and BI at any maturity stage. © 2021 International Society for Horticultural Science. All rights reserved

Kaolin effect on fresh and canned clingstone peach fruit quality and inorganic element composition

Recently, kaolin sprayable materials are studied and used with many crops to control insects and diseases, alleviate heat stress and reduce sunburn damage. Furthermore, kaolin has been found to positively affect fruit external and internal quality with various fruit species. We investigated the effect of kaolin particle film application on fresh and canned clingstone peach fruit quality and inorganic element composition. Kaolin was applied periodically from early July to early August 2010 on 'Andross' peach trees. Fresh peach fruit treated with kaolin and harvested at commercial maturity (middle of August) had increased flesh firmness (FF), soluble solids content (SSC) and acidity and lower water content (WC) compared to control fruit. Kaolin presence on fresh peach fruit skin did not affect L∗, but decreased a∗ compared to control fruit even after kaolin removal with water. In addition, kaolintreated fresh peach fruit had similar P, K, Ca, Mg, Fe, Mn, Zn, Cu, Na, Cd, and Ni and slightly lower Pb contents compared to control peach fruit, while Co and Cr were not detected. Canned peach fruit had modified quality compared to fresh fruit, but most of the differences in quality attributes between kaolin-treated and control fruit remained after canning. Peach fruit color was similar in the two treatments after peeling and canning. Finally, the processed peach fruit treated with kaolin had decreased P, K, Mg, Fe, Mn, Zn, Cu, Ni and similar Ca, Na, Cd, Pb contents compared to processed control fruit, while Co and Cr were not detected. It seemed that certain nutrients leaked from the kaolin-treated processed peach fruit to the syrup resulting in decreased SSC and inorganic element content in the processed peach halves compared to the fresh kaolintreated fruit. © 2015 ISHS