Nectarine Cultivars Research Articles

Effects of Chemical Thinning Agents on the Growth, Fruit Set, Yield and Quality of the Nectarine Cultivar 'Silver King'

The investigation was conducted at the Research Farm of the Division of Fruit Science, SKUAST-Kashmir, Shalimar campus, during 2016 and 2017 to evaluate the effects of chemical thinning agents on vegetative growth, fruit set, yield, and fruit quality of the nectarine cultivar 'Silver King.' The chemicals tested, were Naphthalene Acetic Acid (NAA), Urea, and Ethephon and were applied after petal fall. The findings revealed that NAA (30 ppm) significantly enhanced vegetative parameters such as plant height, shoot elongation, and leaf area. Both NAA and ethephon effectively reduced fruit set and overall yield while improving fruit quality traits, including fruit size, weight, and coloration. Additionally, ethephon (150 ppm) accelerated fruit maturation by 7–8 days. These results indicate that chemical thinning, particularly with NAA and ethephon, holds potential for optimizing fruit quality and marketability in the 'Silver King' nectarine cultivar.

Midwinter Flower Bud and Shoot Tissue Cold Hardiness in 33 Peach Cultivars Grown in New Hampshire, USA

Cold tolerance was measured midwinter in a New Hampshire, USA, orchard collection of 33 peach and nectarine cultivars over 3 years using natural and artificial freezing methods. Flower bud survival and xylem and cambium hardiness were based on the inflection point from nonlinear regression, as well as comparisons of injury at about −20 °C. Flower bud hardiness was greatest in ‘BuenOs’, ‘Contender’, ‘Cresthaven’, ‘Redhaven’, and ‘Scarlet Rose’. The lowest hardiness occurred in ‘Brigantine’, ‘Desiree’, ‘Emeraude’, ‘Evelynn’, ‘Galaxy’, ‘Glenglo’, ‘Jade’, ‘PF5D’, ‘PF23’, ‘Silverglo’, ‘Spring Snow’, and ‘Sugar May’. Other cultivars had either intermediate or inconsistent year-to-year bud hardiness. Bud hardiness in 2021 was weakly correlated with bud hardiness in 2023, but neither were correlated with bud mortality in 2022 after a severe freeze. Cambial hardiness in one year was not correlated with hardiness in other years. ‘August Rose’, ‘BuenOs’, ‘Cresthaven’, ‘Desiree’, and ‘Silverglo’ had the hardiest cambium which was consistent from year to year. Xylem hardiness was greatest in ‘BuenOs’, ‘Contender’, ‘Desiree’, ‘John Boy’, ‘PF17’, ‘Redhaven’, ‘Silvergem’, and ‘TangOs’. Xylem injury was significantly correlated across years indicating that this tissue responds more consistently to midwinter freezing temperatures than flower buds and cambium.

The MYB transcription factor PpMYB5 regulates Pp4CL1/Pp4CL2 expression to promote lignin biosynthesis of fruit russeting in the flat nectarine.

Transcription factor PpMYB5 promotes lignin synthesis by directly binding to the Pp4CL1/Pp4CL2 promoter and affecting their expression, which may be related to nectarine russeting formation. Nectarine russeting is usually considered to be a non-invasive physiological disease that usually occurs on late-maturing cultivars and seriously affects their appearance quality and commercial value. The cause of nectarine fruit rust is currently unknown. In this study, we compared two flat nectarine cultivars, 'zhongyoupanweidi' (HD; russeting-free cultivar) and 'zhongyoupanweihou' (TH; russeting-prone cultivar), with respect to nectarine russeting by means of microscopy, transcriptomics, and hormone analysis. Compared to HD fruits, TH fruits had a broken cuticle, missing wax layer, and heavy lignin deposition. RNA sequencing (RNA-seq) revealed significant alternations in the expression of genes related to lignin synthesis. Moreover, structure genes Pp4CL1 and Pp4CL2, MYB transcription factor (TF) gene PpMYB5 were identified through weighted gene co-expression network analysis (WGCNA). Molecular experiments and transgenic evidence suggested that PpMYB5 regulates Pp4CL1/Pp4CL2 expression to promote lignin synthesis. Overall, in addition to providing new insights into the formation of mechanisms for nectarine russeting, our study also establishes a foundation for nectarine russeting prevention.

Volatile Metabolites to Assess the Onset of Chilling Injury in Fresh-Cut Nectarines.

Fresh-cut processing is a good strategy to enhance the commercialization of peaches and nectarines, which easily deteriorate during low-temperature storage mostly due to the occurrence of chilling injury. Although several studies have been performed to improve the shelf-life of fresh-cut stone fruit, the achievement of high-quality fresh-cut peaches and nectarines still constitutes a challenge. The present study aimed to gain insights into the evolution of the postharvest quality of fresh-cut nectarines (Prunus persica L. Batsch) Big Bang, cold-stored at two different storage temperatures (4 and 8 °C) for up to 10 days. Several aspects influencing the quality traits (sensory and postharvest quality parameters; the profile of phenolic and volatile organic compounds (VOCs)) were explored to predict the marketable life of the fresh-cut nectarines. The respiration rate was higher in samples stored at 4 °C, while the browning process was more evident in fruit stored at 8 °C. Partial Least Squares Regression performed on VOCs showed that samples stored at 4 °C and 8 °C presented a different time evolution during the experiment and the trajectories depended on the interaction between time and temperature. Moreover, Multiple Linear Regression analysis discovered that the 17 VOCs affected by the storage conditions seemed to suggest that no chilling injury was detected for nectarines Big Bang. In conclusion, this approach could also be used with other nectarine cultivars and/or different stone fruits.

Physio-Biochemical Insights into the Cold Resistance Variations among Nectarine (Prunus persica (L.) Batsch var. nectarina) Cultivars.

Cold stress occurs in late winter and early spring threatens greatly the nectarine industry. In this study, the semi-lethal low temperature (LT50) and thirteen cold resistance related parameters of five nectarine cultivars, including 'Nonglehong little princess' (LP), 'Luyou No. 5' (LY), 'Nonglehong No. 6' (NL), 'Zhongyou No. 20' (ZY) and 'Qiuhongzhu' (QH), were determined. Based on these parameters, they were categorized into high-(HR, including NL and LP), moderate-(MR, including QH) and low-cold resistant (LR, including ZY and LY) groups. The relative water (RW), proline (PRO), soluble sucrose (SS) and soluble protein (SP) contents, and superoxide dismutase (SOD) and peroxidase (POD) activities of HR cultivars were higher while their relative electronic conductivity (RE), malondialdehyde (MDA) and gibberellin acid (GA3) contents and catalase (CAT) activity were lower than other cultivars during natural overwintering. Redundancy analysis revealed that the lowest temperature in a day (LT) and LT50 significantly explains 69.8% and 10.9% of these physiological variables, respectively. Moreover, GA3 and indoleacetic acid (IAA) contents and CAT activity were positively correlated, while PRO, SS, ABA and RW contents were negatively correlated with both LT and LT50. Our study will be helpful in understanding the cold resistance variations of nectarine germplasm resources.

Morfološka i kemijska analiza introduciranih sorti nektarine u Hercegovini

A 2-year study was done to compare fruit morphological and chemical composition of three nectarine cultivars grown in south Hercegovinia conditions. A high variability among and within cultivars was found and significant differences were observed among them in all properties analyzed. On the basis of evaluated data, the best fruit performance was registered in ‘Caldesi 2000’ and ‘Venus’ grown in the condition of this part of the Mediteran. This evaluation may help to select a set of nectarine cultivars with better fruit quality attributes, which in our growing conditions might be indicated in ‘Caldesi 2000’ and somewhat in ‘Venus’. The highest average of fruit width (61.18 mm) and fruit weight (148.24 g) was found in cultivar Caldesi 2000. As for friut thickness, also cultivar Caldesi 2000 had the highest value (55.39 mm). The results for the highest fruit length (60.48 mm) had Venus cultivar also fruit stone weight length, width and thickness. The contents sugars (glucose, fructose) total soluble dry matter, and total acids in fruits were found in cultivar Venus, but pH and sucrose were found in cultivar Sun Grand.

Metabolism and transcriptional regulation in chilling injury development of nectarine fruit during postharvest cold storage

Peach fruit is susceptible to chilling injury during postharvest long-term cold storage, but the understanding of metabolic and transcriptional reaction of nectarine cultivar fruit to cold storage remains incomplete. In this study, nectarine fruit was used for a low temperature treatment, which gradually leading to the deterioration of fruit quality. Comparative metabolome and transcriptome analyses were performed to comprehensively understand the metabolic and transcriptional changes occurring during cold storage in nectarine fruit. The result showed that numerous primary and secondary metabolites exhibited increased levels following the low-temperature treatment. And there were 3400 differentially expressed genes continuously regulated by cold storage, which were mostly enriched in metabolic and secondary metabolite biosynthesis pathways. The combined pathways enrichment of differential metabolites and genes were primarily centered on secondary metabolite biosynthesis. Correspondingly, a strong correlation was observed between changes in secondary metabolites and the expression of key enzymes including 4-coumarate CoA ligase (4CL), hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyl transferase (HCT), flavonol synthase (FLS), dihydroflavonol reductase (DFR), and UDP-glycose flavonoid glycosyltransferase (UFGT), which were involved in flavonoids biosynthesis. Additionally, several fruit quality characteristics (carotenoids, cell wall components, antioxidant enzymes) and stress related signaling genes were markedly affected by cold storage. These findings offer new insights into the networks governing metabolic and transcriptional regulation during nectarine fruit cold storage.

Cultivares e novas seleções IAC de pêssego para regiões de inverno ameno

Abstract Traditional peach production regions provide adequate chill for satisfactorily bud’s flower break dormancy, in cultivars there developed. However, considering the expansion of the orchards in mild winter areas and the expected global trends to warmer conditions, the local development of cultivars became relevant. Based on this background, this study proposed to evaluate the performance of 33 peach and nectarine cultivars and selections in mild winter climate. Features associated to the vegetative development, phenology, productivity and fruit characteristics were measured in nine seasons, and the data analyzed by multivariate analysis of variance. Significant correlations between features were remarked. The Pillai and F tests presented significant results, highlighting significant differences among cultivars for almost all features. Peach and nectarine genotypes showed genetic diversity that may be accessed for use as cultivars, or parental for crosses. ‘IAC Aurora 1’, ‘IAC Aurora 2’, ‘IAC Centenário’, ‘IAC Douradão’, ‘IAC Jóia4’, ‘IAC Ouromel 3’, ‘IAC Régis’, ‘Diamante’, ‘Eldorado’, ‘FlordaPrince’, ‘Premier’ and ‘Tropic Beauty’ were the cultivars with the best results. A large number of selections showed promising results, emphasizing, the ‘IAC 680-177’, ‘IAC 1085-27’, ‘IAC 785-9’, ‘IAC 2982-31’, ‘IAC 4682-45’and ‘IAC 6882-84’.

Growth, yield, and biochemical behaviors of important stone fruits affected by plant genotype and environmental conditions

Stone fruit breeders face a significant challenge in obtaining new and high-yielding cultivars, and utilizing unknown ones. Among stone fruit, peaches and nectarines are the most prominent fruits. To address this issue, three independent experiments were conducted on various peach and nectarine cultivars and genotypes at two locations in Iran during 2018–2019 and 2019–2020 using a randomized complete block design with three replications. The results showed significant variations in growth, yield, and biochemical behaviors among the different genotypes and cultivars. 'Henri' was found to have superior yield, tissue firmness, and total soluble solids. Additionally, certain peach cultivars, such as 'Fayette', 'Sorkho-Sefid-Mashhad', and 'Shandabad', had higher yield efficiency than the control cultivar 'J.H. Hale'. Furthermore, 'PMsh-5′ had higher levels of ascorbic acid, antioxidant capacity, and carotenoids. 'Haj-Kazemi' had the tallest average tree height, trunk diameter, and crown of the tree in Golmakan, while 'Anjiri-Zaferani' had the highest levels of total soluble solids, flavor index, and pH. Based on these findings, 'Flamino', 'Nectared', and 'Henri' are recommended as the best nectarine cultivars in Mashhad due to their high pomological and phenological traits. 'Shasta', 'Sorkho-Sefid Mashhad', and 'Suncrest', as well as 'Fayette' and 'Shandabad-Hasteh-Joda' peaches, are recommended as superior cultivars for Mashhad and Golmakan, respectively. This study highlights the importance of selecting appropriate cultivars for optimal growth and yield and emphasizes the need for further research in stone fruit breeding.

Evaluation of the Fruit Quality and Phytochemical Compounds in Peach and Nectarine Cultivars.

Qualitative traits and chemical properties of 32 peach cultivars (yellow flesh and white flesh fruits) and 52 nectarine cultivars (yellow flesh and white flesh fruits) of different pomological characteristics is performed, and the correlation between cultivars and chemical characteristics is analyzed. Yellow nectarines have a higher variability in soluble solids concentration (SSC) and titratable acidity (TA) values. Evaluation of color parameters (a*, b*, L*) shows a significant interaction between pulp color (white vs. yellow) and types (peaches vs. nectarines) of fruit. The difference between yellow and white fruits is stronger in nectarines than in peaches. Sucrose is the main sugar detected in peach fruits, with a percentage content of 78.37% and 76.70% of the total sugar content in yellow and white peaches, respectively, and 78.29% and 78.12% in yellow and white nectarines, respectively. Variability is found among cultivars for the chemical compounds analyzed. The yellow flesh has higher amounts of total carotenoids and TPC, while white-flesh fruits present an average antioxidant value higher than yellow-flesh fruits. No significant correlation is found for polyphenol content and DPPH, while an interaction (p < 0.005) between neochlorogenic acid content and peaches and nectarines is evidenced, with a neochlorogenic acid content higher in nectarines than in peaches.

Nano-calcium alleviates the cracking of nectarine fruit and improves fruit quality

To explore the use of L-aspartic acid nano-calcium (nano-Ca) to reduce nectarine fruit-cracking, we sprayed the crack-susceptible nectarine cultivar ‘Huaguang’ [Prunus persica (L.) Batsch var. nectarina (Ait.) Maxim.] with nano-Ca. The results showed that nano-Ca could reduce the fruit-cracking percentage of nectarine by more than 20%. Nano-Ca was effective because it increased the calcium pectinate content of the peel, reduced the activity of cell-wall metabolic enzymes, and changed the peel structure and enhanced its toughness. We also found that nano-Ca enhanced calmodulin activity in leaves, upregulated key genes of sucrose synthesis in leaves and sucrose transport in stem phloem, and significantly increased the soluble sugar content in the fruit by more than 2%. In addition, Nano-Ca also enhanced calmodulin activity in peel and up-regulated key genes related to anthocyanin-synthesis, promoting anthocyanin accumulation in the peel. The result will lay a theoretical foundation for the physiological and molecular mechanisms of nectarine-cracking and its prevention.

Impact of Chill and Heat Exposures under Diverse Climatic Conditions on Peach and Nectarine Flowering Phenology.

The present study aims to generalize cultivar-specific tree phenology responses to winter and spring temperatures and assess the effectiveness of the Tabuenca test and various chill and heat accumulation models in predicting bloom dates for a wide range of climatic conditions and years. To this end, we estimated the dates of rest completion and blooming and correlated them with observed bloom dates for 14 peach and nectarine cultivars that were evaluated in 11 locations across Europe (Greece, France, Italy, Romania and Spain), within the EUFRIN cultivar testing trial network. Chill accumulation varied considerably among the studied sites, ranging from 45 Chill Portions (CP) in Murcia-Torre Pacheco (Spain) to 97-98 CP in Cuneo (Italy) and Bucharest (Romania). Rest completion occurred latest or was not achieved at all for some cultivars in the southern sites in Murcia. Dormancy release happened earliest in Bucharest and Cuneo, sites where heat accumulation had a strong influence on the regulation of bloom time. Blooming occurred earliest in the moderately cold regions of Lleida (Spain) and Bellegarde (France), and 7-11 days later in the warmer locations of Rome (Italy) and Naoussa (Greece), suggesting that bloom timing is strongly influenced by delayed rest completion in these locations. The Dynamic Model resulted in both more homogeneous chill accumulation across years and better predictions of bloom dates, compared with the Utah, Positive Utah and Chilling Hours models. Prediction of bloom dates was less successful for low-chill cultivars than for medium- and high-chill cultivars. Further climatic and experimental data are needed to make estimates of the climatic needs of peach cultivars more robust and to generate reliable advice for enhancing the resilience of peach production under varying and changing climatic conditions.

Foliar Fertilization of Potassium Silicon Improved Postharvest Fruit Quality of Peach and Nectarine [Prunus persica (L.) Batsch] Cultivars

Peach fruit quality is dependent on preharvest treatments and orchard practices. The aim of this study is to evaluate the effects of preharvest potassium silicon fertilization on fruit postharvest quality. Two peach cultivars (“Early Bomba” and “Plagold 17”) were sprayed with three concentrations of potassium silicon (K-Si) at fruit set, stone hardening, and physiological maturity stages. The applied treatments corresponded to control (T0 = 0% K-Si) pulverized with distilled water and two K-Si treatments (T1 = 3% K-Si and T2 = 4.5% K-Si). The blooming and harvesting dates, vegetative growth and agronomical parameters were analyzed over two growing seasons (2021–2022). Peach fruits were stored at 5 °C and 95% RH during two cold storage periods (2 and 4 weeks) followed by 2 days at room temperatures. The fruit weights (FW), color, firmness, soluble solids content (SSC), titratable acidity (TA), pulp stone ratio (P/S) and fruit weight loss (FWL) were evaluated. The anthocyanins, flavonoids, total phenolics, carotenoids and antioxidant capacity (DPPH) were determined. Vitamin B5 and vitamin C were analyzed by HPLC. The ethylene rate and the chilling injury symptoms (CI) were analyzed after two cold storage periods (2 and 4 weeks). Results showed that the applied potassium silicon treatments (3% K-Si and 4.5% K-Si) enhanced the FW, SSC, TA, FWL, fruit composition and CI. Anthocyanins and total phenolics increased after cold storage period under K-Si treatments. The nectarine cultivar (cv) Early Bomba showed low sensibility to chilling injury symptoms as compared to the cv Plagold 17.

Relationship between crop load and fruit quality in low-chill peaches and nectarines

ABSTRACT Fruits from low-chill peach and nectarine cultivars have lower quality in comparison with traditional varieties. One of the factors that most affect both fruit quality and fruit yield is the crop load (CL). The objective of the present work was to evaluate the relationship between CL and the external and internal fruit quality of low-chill peaches in a temperate-subtropical transition zone of the central-east region of Santa Fe province (Argentina). Fruit diameter (mm), total soluble solids (°Brix), titratable acidity (%), juiciness (%), skin red over-colour (%) and the Commission Internationale de l'Elcairage (CIE) colour parameters, and fruit yield efficiency (kg cm−2 trunk cross-sectional area; TCSA) were evaluated in nine low-chill peach cultivars under three CL treatments: 1.0 (low), 1.5 (medium) and 2.0 (high) fruit cm−2 TCSA. Increasing from low to medium CL did not affect the internal or external fruit quality attributes of any of the nine low-chill cultivars studied but increased fruit yield from 20% to 44% according to the genotype. In some cultivars, such as ‘Don Agustín’ and ‘Lara’, it was possible to increase the CL to 2 fruit cm−2 TCSA without affecting fruit quality.

Earliness, Yield, and Fruit Quality Attributes of Low-Chilling Peach-Nectarine Cultivars with the Application of Low Biuret Urea and Calcium Nitrate

This study aimed to determine the effects of low biuret urea and calcium nitrate application on earliness, fruit set, yield, and fruit quality characteristics in ‘Astoria’, ‘Maya’ peaches, and ‘Garbaja’ nectarine cultivars. In the study, Bud Feed (low biuret urea 15%) and calcium nitrate (calcium oxide 12% and total nitrogen 7%) were applied 35 days before bud break. In this study, flowering and fruit set, harvest times, fruit yield, and quality characteristics were evaluated. The source of temperatures used to calculate chill accumulation (expressed as hours below 7°C and chill unit) and growing degree hours was investigated. Bud Feed application provided earliness of 2 days in ‘Astoria’ and ‘Garbaja’ cultivars and 3 days in ‘Maya’ cultivar. This application was showed positive effect on flowering and final fruit set in all cultivars compared to control plants. The application was more effective in increasing the yield per tree by 33.72% (‘Astoria’), 41.00% (‘Maya’), and 52.18% (‘Garbaja’). Bud Feed application was improved fruit size in ‘Garbaja’ and ‘Astoria’ cultivars, whereas provided more intense fruit skin color in ‘Maya’ and ‘Garbaja’ cultivars. These results showed that bud feed and calcium nitrate application can be used to prevent yield and fruit quality losses in peach-nectarines in warm winter under Mediterranean climate conditions.

Transcriptional profiling of the terpenoid biosynthesis pathway and in vitro tests reveal putative roles of linalool and farnesal in nectarine resistance against brown rot

The most devastating fungal disease of peaches and nectarines is brown rot, caused by Monilinia spp. Among the many plant responses against biotic stress, plant terpenoids play essential protective functions, including antioxidant activities and inhibition of pathogen growth. Herein, we aimed to characterize the expression of terpenoid biosynthetic genes in fruit tissues that presented different susceptibility to brown rot. For that, we performed artificial inoculations with Monilinia laxa at two developmental stages (immature and mature fruit) of two nectarine cultivars (‘Venus’ –mid-early season cultivar - and ‘Albared’ –late season cultivar-) and in vitro tests of the key compounds observed in the transcriptional results. All fruit were susceptible to M. laxa except for immature ‘Venus’ nectarines. In response to the pathogen, the mevalonic acid (MVA) pathway of the ‘Venus’ cultivar was highly induced in both stages rather than the methylerythritol phosphate (MEP) pathway, being the expression of some MEP-related biosynthetic genes [e.g., PROTEIN FARNESYLTRANSFERASE (PpPFT), and 3S-LINALOOL SYNTHASE (PpLIS)] different between stages. In ‘Albared’, both stages presented similar responses to M. laxa for both pathways. Comparisons between cultivars showed that HYDROXYMETHYLGLUTARYL-CoA REDUCTASE (PpHMGR1) expression levels were common in susceptible tissues. Within all the terpenoid biosynthetic pathway, linalool- and farnesal-related pathways stood out for being upregulated only in resistant tissues, which suggest their role in mediating the resistance to M. laxa. The in vitro antifungal activity of linalool and farnesol (precursor of farnesal) revealed fungicidal and fungistatic activities against M. laxa, respectively, depending on the concentration tested. Understanding the different responses between resistant and susceptible tissues could be further considered for breeding or developing new strategies to control brown rot in stone fruit.

Impact of Ozonated Water on Brown Rot Development and Storage Potential of Nectarine and Plum

ABSTRACT Postharvest fruit rot is one of the most serious diseases of fleshy stone fruits such as nectarine and plum. The efficacy of ozonated water sprayed in different doses in a packing line [low dose, 1.5 ppm ozone (Ο3) for 100 sec; medium dose, 3.0 ppm Ο3 for 100 sec; high dose, 1.5 ppm Ο3 for 400 sec] in controlling the brown rot (Monilinia fructicola) development was studied in the nectarine cultivar ‘Τasty Free’ and the plum cultivar ‘Angelino.’ Changes in flesh firmness, ripening index, ethylene and respiration rate, and peel color during storage (0℃ for 3 weeks) and shelf-life (20℃ for 4 days) were used as ‘indicator’ quality parameter responses in storage and shelf-life. The most efficient dose of O3 in controlling the Monilinia infection was the highest applied, followed by the middle O3 dose. The efficacy of O3 treatments was higher when a lower Monilinia spore concentration was applied. The O3 doses applied did not cause any visible symptoms of O3 toxicity, yet they caused an acceleration in the fruit ripening process, suggested mainly by an increase in the fruit respiration rate in both nectarine and plum, and an increase in the ripening index and darker peel coloration only in plums. In conclusion, spraying with ozonated water is an eco-friendly and efficient sanitizing agent, but in fleshy commodities such as nectarine and plum may diminish their postharvest performance.

Development of new nectarine cultivars with low chilling requirements, adapted to climate change

Development of new nectarine cultivars with low chilling requirements, adapted to climate change

‘Zhongyoupanweimei’: A Flat Nectarine Cultivar from the Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences

"‘Zhongyoupanweimei’: A Flat Nectarine Cultivar from the Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences" published on Dec 2022 by American Society for Horticultural Science.

Effect of mucilage edible coating on fresh-cut nectarine cultivar ‘Big Bang’

Effect of mucilage edible coating on fresh-cut nectarine cultivar ‘Big Bang’