Stone Fruit Cultivars Research Articles

Mediterranean fruit fly population phenological patterns are strongly affected by elevation and host presence

The Mediterranean fruit fly (medfly) (Ceratitis capitata, Diptera: Tephritidae), is an extremely polyphagous pest that threatens the fruit production and trading industry worldwide. Monitoring C. capitata populations and analysing its dynamics and phenology is considered of outmost importance for designing and implementing sound management approaches. The aim of this study was to investigate the factors regulating the population dynamics of the C. capitata in a coastal and semi-mountainous area. We focused on effects of topography (e.g. elevation), host presence and seasonal patterns of ripening on the phenological patterns considering data collected in 2008. The experimental area is characterized by mixed fruit orchards, and Mediterranean climate with mild winters. Two trap types were used for population monitoring. The female targeted McPhail type and the male targeted Jackson type. Traps were placed in farms located at different elevations and landscape morphology (coastal and semi-mountainous areas). The main crops included citrus, apples, peaches, plums, pears, figs, quinces and apricots. Adult captures were first recorded in May, peaked in mid-summer and mid-autumn and almost ceased at the end of the season (January 2008). Captures in the coastal areas preceded that of highlands by 15 days. Most of the adults detected during the fruit ripening of late stone fruit cultivars (first peak) and citrus (second peak). The probability of capturing the first adults preceded almost three weeks the peak of adult captures either considering the elevation or host focus analyses. The results provide valuable information on the seasonal population trend of C. capitata in mixed fruit Mediterranean orchards and can support the set-up of IPM systems in areas with various landscapes and different hosts throughout the fruit growing season.

Harvesting & Postharvest Handling of Stonefruit in Florida

Stonefruit grown commercially in Florida include peaches, nectarines, and plums. This publication is directed to current and potential stonefruit growers, handlers, and marketers, as well as researchers, extension agents, students, and consumers. It provides information about the Florida stonefruit industry, stonefruit cultivars that are suitable for Florida, stonefruit postharvest physiology and pathology, fruit quality, and recommended postharvest handling and marketing practices.

Relationships between Soluble Solids and Dry Matter in the Flesh of Stone Fruit at Harvest

Soluble solids concentration (SSC) is a reference index that is typically used to quantify soluble sugars, the most abundant constituents of stone fruit flesh dry matter when approaching maturity. Dry matter concentration (DMC) is another parameter that has been often associated with fruit quality. This study investigated the relationship of SSC and DMC in fourteen stone fruit cultivars at harvest. SSC and DMC were measured at physiological maturity in peach, nectarine, plum and apricot. SSC and DMC data had similar symmetrical patterns (range, means and variability) for most of the cultivars. Mean SSC ranged between 11.6 and 19.7 °Brix, and DMC between 11.6% and 19.4% w/w across all fruit studied. High variability in SSC was observed in apricot, with an interquartile range = 5.7 °Brix. A generic linear regression model that included peach, nectarine and plum cultivars revealed a robust association between DMC and SSC (p < 0.001, R2 = 0.914, n = 2800) with a DMC prediction error (RMSE) equal to 0.874% w/w. However, when a simplified DMC = SSC was used for DMC estimation, the RMSE only slightly increased and was still lower than 1.00% w/w. Similar results were observed when linear regression models were assessed in each cultivar independently, with R2 > 0.75 and RMSE generated by the simplified DMC = SSC model lower than 1.00% w/w in thirteen out of fourteen stone fruit cultivars, with the exception of the apricot cultivar. These results provide empirical evidence that SSC and DMC are highly correlated fruit quality indicators in plum, peach and nectarine at harvest.

The role of Prunus cerasifera Ehrh. in the origin, evolution and improvement of stone fruit cultivars

At Krymsk Experiment Breeding Station of VIR, as a result of collecting, studying, and selective use of myrobalan plum genetic diversity, the intraspecific taxonomy of the species Prunus cerasifera Ehrh. was clarified. Donors of traits significant for breeding were identified and, with their use, adaptable cultivars of myrobalan plum, Russian plum and clonal rootstocks of stone fruit plants were developed.Intraspecific classification of P. cerasifera is proposed, with the identified subspecies:subsp. cerasifera (typical myrobalan plum);subsp. orientalis (M. Pop.) Erem. et Garcov. (Oriental myrobalan plum);and subsp. macrocarpa Erem. et Garcov. (large-fruited myrobalan plum).Within subsp. P. cerasifera subsp. macrocarpa, varieties were identified:var. macrocarpa (typical, or Krymsk);var. georgica Erem. et Garcov. (Georgian);var. iranica (Koval.) Erem. et Garcov. (Iranian);var. nairica (Koval.) Erem. et Garcov. (Armenian);var. pissardii Carr. (Pissard);and var. taurica (Kost.) Erem. et Garcov. (Taurida).The participation of myrobalan plum in the origin of spp. P. brigantiaca Vill., P. cocomilia Tem., and P. spinosa L. was traced. Involvement of large-fruited myrobalan plum in hybridization with blackthorn contributed to the manifestation of an exceptional polymorphism among the varieties of the hybridogenic species P. domestica L. (P. cerasifera × P. spinosa). As a result of hybridization between myrobalan plum and Chinese plum varieties, a new cultigen species emerged – Russian plum (× P. rossica Erem.). By now, 127 cultivars of this species and 7 clonal rootstocks for stone fruit crops have been developed. These cultivars and clonal rootstocks are zoned for Russia and a number of other countries.

Pollen performance modelling with an artificial neural network on commercial stone fruit cultivars

Pollen tube growth and pollen germination percentage are key factors for successful fruit set. Pollen performance is critical for the production and breeding of flowering plants and in agricultural systems in terms of fruit development. This study was carried out to predict pollen tube growth and pollen germination percentage in four stone fruits species (cherry (Prunus avium), apricot (Prunus armeniaca), plum (Prunus domestica), and peach (Prunus persica)) using a neural network. For this purpose, we measured pollen tube length and pollen germination rates under in vitro conditions. For the in vitro test, pollen grains of four stone fruit cultivars were sown in three different media and incubated at seven different temperatures for four incubation periods. A layered neural network was used for estimating the pollen germination rate and pollen tube length related to the in vitro condition. This study suggests a method for estimating the pollen germination rate and pollen tube length using artificial neural networks. The performed artificial neural networks produced an efficient prediction from in vitro data. The determination coefficients obtained between the observed and predicted data sets are 0.86 (for germination rate) and 0.81 (for tube length), indicating an accurate estimation of the in vitro data. In our case, the network that produced the best result had a 4:9:2 architecture.

RE-DESCRIPTION OF THE LAST INSTAR LARVAE OF CAPNODIS TENEBRIONIS (LINNAEUS, 1760) (COLEOPTERA, BUPRESTIDAE) DEPENDING ON SCANNING ELECTRON MICROSCOPE

The flat-headed borer, Capnodis tenebrionis (Linnaeus, 1760) , dispersed extensively in various geographical regions; it is extremely harmful and a dire threat to most stone fruit cultivars, and once the larva enters under the host tree crown, the infested host tree will gradually dry and eventually die. In this study, specimens were collected from several sites in Erbil province, Kurdistan Region- Iraq; then the fully grown larvae were selected for morphological study. In addition, clarification of morphological consequential and implication for most diagnostic characters were studied in all dissected parts. Scanning electron microscope (SEM) was used to further analyze the hidden features of the selected characteristics; those were not shown in the primary mounting. The results impressively presented new conclusive evidence for the descriptive illustration of C. tenebrionis, and it confirmed a precise identification of this species in the larval stage.

Ethyl formate fumigation: Its effect on stone and pome fruit quality, and grain chinch bug (Macchiademus diplopterus) mortality

The grain chinch bug, Macchiademus diplopterus (Distant) (Hemiptera: Lygaeidae), is a key phytosanitary pest requiring postharvest mitigation control for successful export of South African deciduous fruit. The main aims of the present investigation was to examine, firstly, the potential of ethyl formate as a fumigant to control the grain chinch bug and secondly, the effect of ethyl formate on the fruit quality of selected stone and pome fruit cultivars. The preliminary trial indicated a minimum concentration of 50 g/m3 (or 50 mg/L) ethyl formate for 1 h was required to obtain 100% mortality of the grain chinch bug. Building on those findings, phytotoxic trials assessed the effect of applying a dose range of 50–150 g/m3 ethyl formate for 1 h in desiccators at ambient temperature on various pome and stone fruit cultivars. No internal or external phytotoxic damage was observed on the various cultivars. An informal tasting panel could not distinguish between treated and untreated fruit. The effect of packaging (cartons with perforated bags or liners as per commercial use for each product) on the ability of ethyl formate to control the grain chinch bug was assessed after the phytotoxic susceptibility trials. The introduction of packaging confirmed that a higher concentration of ethyl formate (85 g/m3) was required for packaged fruit compared to the 50 g/m3 required for open crates or lugs. Higher ethyl formate concentrations enabled the fumigant to diffuse and penetrate the different packaging types without a dilution effect, effectively controlling the grain chinch bug embedded inside the cartons while maintaining fruit quality.

Health effects of sour cherries with unique polyphenolic composition in their fruits

Health effects of fruit consumption are confirmed by many studies. Such effects are attributed to the polyphenolic compounds accumulating in fruit skin and mesocarp tissues. They contribute to the regulation on transcriptional, post-transcriptional and epigenetic levels. Since people consume much less fruits than the recommended quantities, a new approach includes the promotion of super fruits that are extremely rich sources of specific health compounds. A comparative analysis of Hungarian stone fruit cultivars detected a huge variability in fruit in vitro antioxidant capacity and total polyphenolic content. Two outstanding sour cherry cultivars ('Pipacs 1' and 'Fanal') were identified to accumulate elevated levels of polyphenolic compounds in their fruits. Sour cherries with different polyphenolic compositions were tested against alimentary induced hyperlipidemia using male Wistar rat model. Consumption of cherry fruit had different consequences for different cultivars: consumption of 'Pipacs 1' and 'Fanal' fruits resulted in 30% lower total cholesterol levels in the sera of hyperlipidemic animals after only 10 days of treatment. However, the consumption of 'Újfehértói fürtös' fruit has not induced significant alterations in the same parameter. Other lipid parameters also reflected the short-term beneficial effects of 'Pipacs 1' and 'Fanal' fruits. We suggest that not only some tropical and berry fruits might be considered as super fruits but certain genotypes of stone fruits as well. These have indeed marked physiological effects. Since 'Pipacs 1' and 'Fanal' are rich sources of colourless polyphenolics (e.g., phenolic acids and isoflavonoids) and anthocyanins, respectively, the protective effects associated with their consumption can be attributed to different polyphenolic compounds. Orv Hetil. 2018; 159(18): 720-725.

Discovery of non-climacteric and suppressed climacteric bud sport mutations originating from a climacteric Japanese plum cultivar (Prunus salicina Lindl.).

Japanese plums are classified as climacteric; however, some economically important cultivars selected in California produce very little ethylene and require long ripening both “on” and “off” the tree to reach eating-ripe firmness. To unravel the ripening behavior of different Japanese plum cultivars, ripening was examined in the absence (air) or in the presence of ethylene or propylene (an ethylene analog) following a treatment or not with 1-methylcyclopropene (1-MCP, an ethylene action inhibitor). Detailed physiological studies revealed for the first time three distinct ripening types in plum fruit: climacteric, suppressed-climacteric, and non-climacteric. Responding to exogenous ethylene or propylene, the slow-softening supressed-climacteric cultivars produced detectable amounts of ethylene, in contrast to the novel non-climacteric cultivar that produced no ethylene and softened extremely slowly. Genetic analysis using microsatellite markers produced identical DNA profiles for the climacteric cultivars “Santa Rosa” and “July Santa Rosa,” the suppressed-climacteric cultivars “Late Santa Rosa,” “Casselman,” and “Roysum” and the novel non-climacteric “Sweet Miriam,” as expected since historic records present most of these cultivars as bud-sport mutations derived initially from “Santa Rosa.” This present study provides a novel fruit system to address the molecular basis of ripening and to develop markers that assist breeders in providing high-quality stone fruit cultivars that can remain “on-tree,” increasing fruit flavor, saving harvesting costs, and potentially reducing the need for low-temperature storage during postharvest handling.

Genetic diversity in peach [Prunus persica (L.) Batsch] at the University of Florida: past, present and future

The University of Florida (UF) stone fruit breeding and genetics program was created in 1952 to develop early ripening stone fruit cultivars with high quality, adaptation to summer rainfall, low chilling requirements, and the ability to withstand high disease pressure. Diverse germplasm sources were used to introduce desirable traits in UF breeding pool. The main objective of this research was to determine the genetic diversity and population structure of the breeding germplasm, and to search for loci under selection. A total of 195 peach genotypes were used: UF cultivars and advanced selections (n = 168), cultivars and selections from the UF-UGA-USDA joint breeding effort (n = 13), landrace cultivars (n = 4), high-chilling cultivars released by NCSU (n = 5), and related Prunus (n = 5) species. A total of 36 SSR markers distributed across the peach genome amplified 423 alleles. An average of 18 genotypes were detected per marker: A (number of observed alleles) of 11.43, Ae (effective number of alleles) of 2.58, Ho (observed heterozygosity) of 0.4, He (expected heterozygosity) of 0.52, F (Wright’s fixation index) of 0.25, and PIC (polymorphism information content) of 0.48. UPGMA cluster analysis based on Nei’s genetic distance represented best the known pedigree information for the germplasm pools. Two major groups were observed across the germplasm corresponding to melting and non-melting flesh cultivars/selections. Population structure results supported these two major groups. Several loci closely located to genome regions where different phenotypic traits have been previously mapped were detected to be under selection.

S-locus genotyping on stone fruits in Hungary: a review of the most recent achievements

Central Europe can be taken as a geographical and historical connection zone between the western growing countries and Asian gene centres of Prunus tree fruits. The determination of the S-genotype of stone fruit (mainly almond, plum, cherries and apricot) cultivars and landraces has both practical and theoretical significance. Our group has allocated complete S-genotypes for more than 200 cultivars and selections of almond, Japanese plum, sweet cherry and apricot. Among Eastern European almond cultivars, two novel cross-incompatibility groups (CIGs) were identified. S-alleles of a related species were also shown in P. dulcis accessions; a fact seems to be indicative of introgressive hybridization. Our results with Japanese plum clarified and harmonized two different allele nomenclatures and formed a basis for intensive international studies. In apricot, a total of 13 new S-alleles were identified from Eastern European and Asian accessions. Many Turkish and North African cultivars were classified into new CIGs, III–XVII. Results suggest that the mutation rendering apricot self-compatible might have occurred somewhere in south-east of Turkey and we were successful to confirm the presumed Irano-Caucasian origin of North African apricots based on the geographical distribution of S-alleles. In sweet cherry, new alleles have been identified and characterized from Turkish cultivars and selections. In addition, wild sweet cherry and sour cherry S-alleles were also shown indicating a a broader gene pool in Turkey as compared with international cultivars. We also used S-genotype information of Ukrainian sweet cherry cultivars to design crosses in a functional breeding program. Our results exhibit an increased number of S-alleles in tree fruit accessions native to the regions from Eastern Europe to Central Asia, which can be used to develop S-genotyping methods, to assist cultivation and draw inferences for crop evolution.

NEW ROOTSTOCKS WITH RESISTANCE TO PLUM POX VIRUS FOR PRUNUS DOMESTICA AND OTHER STONE FRUIT SPECIES: THE 'DOCERA' AND 'DOSPINA' ROOTSTOCK SERIES

ISHS X International Symposium on Plum and Prune Genetics, Breeding and Pomology NEW ROOTSTOCKS WITH RESISTANCE TO PLUM POX VIRUS FOR PRUNUS DOMESTICA AND OTHER STONE FRUIT SPECIES: THE 'DOCERA' AND 'DOSPINA' ROOTSTOCK SERIES

Comparative transcript profiling of a peach and its nectarine mutant at harvest reveals differences in gene expression related to storability

Gene expression at harvest was compared for two stone fruit cultivars, a peach and its near-isogenic nectarine mutant, using two microarray platforms, μPEACH1.0 and ChillPeach. Together, both platforms covered over 6,000 genes out of which 417 were differ- entially expressed between the fruits of the two cultivars at a p value of 0.05. A total of 47 genes in nectarine and 60 genes in peach were at least twofold higher relative to each other. Nectarine had much better storage character- istics than peach and could be stored for over 5 weeks at 5 °C without storage disorders. In an attempt to determine whether gene expression at harvest could give an indica- tion of storage potential, the expression analysis of the two cultivars was compared to that of two genotypes with different sensitivities to chilling injury. Principal compo- nent analysis of gene expression results across four fruit types differing in chilling sensitivity resulted in 41 genes whose expression levels separated the fruits according to sensitivity to storage disorders, suggesting that the genes have a role in cold response adaptation.

Incidence of virus fungal diseases on three stone fruits cultivars in Hungary

In this two-year study, incidence of Polystigma rubrum on plum, and Apiognomonia erytrostoma on apricot were evaluated on several stone fruit cultivars in Hungary. Results showed that most apricot cultivars expressed symptoms caused by A. erytrostoma, graded between 2 and 3 (10-50%) by the end of the summer in 2005 and 2006. The most tolerant apricot cultivars were Budapest and Mandulakajszi while the most susceptible ones were ’Magyar kajszi’ and ’Piroska’.Assessments made on plum showed that most of the plum cultivars were tolerant or lowly susceptible to P. rubrum such as ’Ageni’, ’Althann ringló’, ’Bluefre’, ’Cacanska najbolja’, ’Silvia’, ’Ruth Gerstetter’, ’Tuleu gras’ and ’Utility’. The most susceptible plum cultivars to P. rubrum were ’Besztercei clones’ and ’Debreceni Muskotály’.

Preliminary results of in vivo thermotherapy of plum, apricot and peach cultivars artificially infected with PPV-M and PPV-D strains of Plum pox virus

The elimination of <I>Plum pox virus</I> (PPV) in different stone fruit cultivars was verified by the method of thermotherapy <I>in vivo</I>. Trees of two plum cultivars Čačanská lepotica and Švestka domácí, apricot cultivars Leskora and Velkopavlovická, and peach cultivars Redhaven and Earliglo were used. They were infected artificially with two strains of the virus (PPV-D, PPV-M). Two cycles of thermotherapy <I>in vivo</I> were performed. During the first cycle, 16 trees of plum, apricot and peach were treated for 15 days at 37°C. In the second thermotherapy cycle, 10 trees of individual cultivars of plum, apricot and peach were treated for 22 days at 37°C. In the first thermotherapy (T1), 8 trees out of 16 died; PPV was eliminated in 2 trees of cv. Čačanská lepotica, 1 tree of cv. Švestka domácí and 2 trees of cv. Velkopavlovická. In the second thermotherapy (T2), 1 of 10 treated trees died. The virus was eliminated in 2 trees of cv. Čačanská lepotica, 1 tree of cv. Leskora, 2 trees of cv. Velkopavlovická, and 1 tree of cv. Redhaven. Nine (T1) and seven (T2) months after the thermotherapy, the presence of PPV was detected in 6 out of 11 originally recovered trees using ELISA. Out of 26 trees, 4 trees remained recovered: 2 plum trees and 2 apricot trees. One of these trees, apricot cv. Leskora was originally infected with PPV-M strain, whereas the other three with PPV-D strain. None of the 10 peach trees was treated successfully.

Incidence of fungal diseases on leaves of apricot and plum cultivars in Hungary

In this two-year study, incidence of Polystigma rubrum on plum, and Apiognomonia erytrostoma on apricot were evaluated on several stone fruit cultivars in Hungary. Results showed that most apricot cultivars expressed symptoms caused by A. erytrostoma, graded between 2 and 3 (10-50%) by the end of the summer in 2005 and 2006. The most tolerant apricot cultivars were Budapest and Mandulakaj­szi while the most susceptible ones were 'Magyar kajszi' and 'Piroska'. Assessments made on plum showed that most of the plum cultivars were tolerant or lowly susceptible to P. rubrum such as 'Ageni', 'Althann ringló', 'Bluefre', 'Cacanska najbolja', 'Silvia', 'Ruth Gerstetter', 'Tuleu gras' and 'Utility'. The most susceptible plum cultivars to P. rubrum were 'Besztercei clones' and 'Debreceni Muskotály'.

Pseudomonas syringae Diseases of Fruit Trees: Progress Toward Understanding and Control.

Pseudomonas syringae Diseases of Fruit Trees: Progress Toward Understanding and Control.

Diversity of Plum pox virus isolates in Bosnia and Herzegovina

Sixteen Plum pox virus (PPV) isolates from several stone fruit cultivars, host species, orchards and geographical areas of Bosnia and Herzegovina were selected for typing, using serotype‐specific monoclonal antibodies (MAbs) and PCR–RFLP, targeting the 3′ terminal region of the coat protein (CP) and P3‐6K1 with restriction enzymes RsaI and DdeI. Four PPV isolates were identified as PPV‐M by serology and PCR; eight isolates were identified as PPV‐D based on PCR–RFLP on both genomic regions, but were not recognized by the D‐specific MAb4DG5. Four isolates from plum were identified as natural D/M recombinants (PPV‐Rec), based on conflicting results of CP and P3‐6K1 typing. To investigate the genetic diversity of Bosnian PPV isolates in more detail, five isolates (three PPV‐Rec, one PPV‐M and one PPV‐D) were partially sequenced in the region spanning the 3′ terminal part of the NIb gene and the 5′‐terminal part of the CP gene, corresponding to nucleotides 8056–8884. Nucleotide sequence alignment of recombinant isolates showed that they were closely related at the molecular level to previously characterized recombinants from other European countries, and shared the same recombination break point in the 3′ terminal part of the NIb gene. This is the first report of naturally infected Prunus trees with PPV‐M, PPV‐D and PPV‐Rec in Bosnia and Herzegovina. The high variability of the Bosnian PPV isolates fits with the presence of this virus in the country over a long period.

EFFECT OF THE RATE AND DURATION OF FORCED AIR COOLING ON THE QUALITY OF ´IMPERIAL´ APRICOTS AND ´PIONEER´ AND ´SONGOLD´ PLUMS

Gel breakdown (GB) and overripeness (OR) remain the biggest internal problems with Prunus armeniaca L. 'Imperial', which makes the biggest contribution to the total volume of apricots exported from South Africa per annum. Prunus salicina L. 'Pioneer', an early season South African plum cultivar, ripens quickly on and off the tree which results in rejections for soft fruit at packing and on arrival overseas. 'Songold', a yellow, midseason plum cultivar tends to develop GB and OR during cold-storage in some seasons, which renders the fruit inedible and results in high rejection rates. Prompt cooling and good temperature management are essential to lower the rate of physiological deterioration of stone fruit. In some commercial depots in South Africa, forced air cooling (FAC) of stone fruit can take as long as 48 to 72 h, depending on the type of packaging. Consequently, the objective of this study was to determine the effect of the rate and duration of FAC on the fruit quality of different stone fruit cultivars. Fruit was subjected to the following FAC rates at a delivery air temperature of -1.0°C to a pulp temperature of 0°C for 6 h, 12 h, 24 h stepwise cooling and 48 h stepwise cooling for the apricot, and 12 h, 24 h, 48 h stepwise cooling, and 72 h stepwise cooling for the two plum cultivars. The fruit was evaluated after cold-storage and a simulated shelf-life period. The trial was conducted in two consecutive seasons. 'Imperial' apricots had the best internal quality after 6 h of FAC, 'Pioneer' plums were not affected by FAC rate or duration, and 'Songold' plums had the best internal quality when FAC was applied for 12 h and longer. These results on plums demonstrate that cultivar differences must be considered when drawing up handling protocols for stone fruit, as a blanket recommendation may lead to the induction of quality defects.

Trends in Stone Fruit Cultivar Development

Despite the hundreds of existing stone fruit (Prunus spp.) cultivars used for fresh market, there is a continuing need to develop new stone fruit cultivars as the requirements of the industry change. Over the last 20 years there has been a shift toward private breeding as the public sector decreases its support of these long-range programs. As a result there are fewer public breeding programs and many of those still operating protect their releases and partially fund their programs with royalty payments. Other trends that are shaping the development of new stone fruit cultivars are a need for smaller or more easily managed tree architecture, a trend toward the use of fewer agricultural chemicals, the expansion of production zones into the milder winter zones to allow year-round availability of stone fruit, a general diversification of fruit types being marketed, the increased awareness of the health benefits of fruit consumption, the need for better and more consistent quality, and given the global marketing of these fruit the increased need for enhanced postharvest qualities. The breeding programs of the world are responding to these trends and working toward developing the cultivars for the world markets of the future.