Persica Var Research Articles

Synergistic Influence of Melatonin-Hydrocolloid Coating on Decay and Senescence of Nectarine (Prunus persica var. nucipersica) during Supermarket Storage Conditions

Nectarines have remarkable nutritional value, low caloric content, and are rich in antioxidants. However, despite substantial local and global demand, their susceptibility to rapid spoilage during peak summer harvest is limited. To address this issue, the current study investigated the potential benefits of using melatonin (MLT), an antioxidant biomolecule, in combination with edible hydrocolloid coatings like carboxymethylcellulose (CMC) and gum Arabic (G.A.) on ‘Snow Queen’ nectarine fruits. The nectarines were treated with various combinations of coatings, including 1% and 1.5% CMC, 8% and 10% G.A., and 0.1 mM melatonin. These coated and non-coated samples were stored under standard supermarket conditions (18 ± 1 °C, 85–90% R.H.) for 16 days. The outcomes demonstrated that the most effective treatment was the combination of 1% CMC with 0.1 mM melatonin. This treatment significantly (p ≤ 0.05) reduced the rate of respiration, curbed fruit decay by approximately 95%, minimized weight loss by around 42%, and maintained approximately 39% higher levels of total phenol content and roughly 30% greater antioxidant (AOX) activity. These positive effects were accompanied by preserved firmness and overall quality attributes. Moreover, the treatment extended the shelf life to 16 days through retarding senescence and suppressing the activities of lipoxygenase (LOX) and pectin methylesterase (PME), all without compromising the functional qualities of the nectarine.

Comprehensive study of the hormonal, enzymatic and osmoregulatory response to drought in Prunus species

Nowadays, climate change is creating new challenges all over the planet and altering the availability of water resources. Agriculture is one of the most affected sectors, as water is a fundamental requirement for the sustainability of agriculture and future demands. Recurrent drought periods have pushed breeding programs to develop and select genotypes tolerant to water stress. Understanding the mechanisms involved in drought response is essential in facilitating the selection of such genotypes. In this study, we have characterized the levels of enzymatic antioxidants, the soluble sugars content (osmotic response) and the hormone profile of four genotypes of the genus Prunus (P. webbi, P. elaeagnifolia, P. dulcis var. ‘Garrigues’, and P. persica var. ‘Montclar’) and one P. dulcis x P. persica hybrid (‘GF677’) subjected to three different water irrigation conditions (control, drought and recovery). Results show that P. webbi and P. elaeagnifolia, and, to a lesser extent, the cultivar ‘Garrigues’, seem to be the most tolerant to water stress. Drought and recovery treatments led to a differential response in terms of the levels of enzymatic antioxidants depending on the genotype. Elevated levels of the osmotic regulators glucose and fructose and a parallel decrease in sucrose were also observed. Finally, a fine-tuned regulation of abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), and cytokinins (trans-zeatin, tZ, and isopentenyl adenine, iP) took place in P. webbi, P. elaeagnifolia and ‘Garrigues’. In summary, deciphering the tolerance response to water stress of these almond genotypes together with proper breeding efforts could contribute to the development of new drought-tolerant almond cultivars and rootstocks. In this sense, we strongly suggest the use of more unexplored wild almond species in breeding programs to increase diversity and improve environmental stress tolerance-related traits.

Selective recovery of glycosylated phenolic compounds from nectarine tree branches (Prunus persica var. nucipersica)

Nectarine tree branches, by-products from the arboriculture, contain phenolic compounds. Six main components were revealed by LC-MS and divided into 3 aglycones (A) (catechin, chlorogenic acid, naringenin) and 3 glycosylated (G) (rutin, isoquercetin and prunin) molecules. To maximize their content in nectarine tree branches extract, the extraction process was optimized. The optimum conditions were found at 55 % ethanol and 90 °C, leading to 9.05 ± 0.80 mg/gDM of catechin, 3.17 ± 0.31 mg/gDM of chlorogenic acid, 1.15 ± 0.01 mg/gDM of naringenin, 1.56 ± 0.08 mg/gDM of rutin, 0.57 ± 0.02 mg/gDM of isoquercetin, and 1.73 ± 0.11 mg/gDM of prunin. The glycosylated-aglycone ratio is equal to 0.276 ± 0.006, meaning that aglycones are predominant. Purification of the extract was carried out by adsorption. A screening of several resins led to the choice of the XAD-7 resin that provides a recovery rate of 66–84 % of glycosylated compounds and 9–46 % of aglycones. The effect of the adsorption process on the evolution of the G/A ratio was studied. Under the studied conditions, this parameter increased by 123 %, mainly due to a good performance of the XAD-7 towards glycosylated components and a low recovery rate of chlorogenic acid.

Effect of nano-calcium on carotenoid and anthocyanin contents of nectarine fruit

Increasing the carotenoid content of nectarine (Prunus persica var. nucipersica) is of great significance for improving its quality and economic value. A two years study was carried out on ‘Shuguang’ nectarine to evaluate the effect of calcium chloride (Cl–Ca) and L-aspartic acid nano calcium [Ca (L-asp) - NPs] (nano-Ca) on carotenoid accumulation. The results show that both Cl–Ca and nano-Ca could increase the carotenoid content of nectarine fruit flesh, but the effect of nano-Ca was more significant. Nano-Ca is more easily absorbed by nectarine leaves and fruits, which improves the calmodulin activity of leaves, peel and flesh, and up-regulates the expression of carotenoid synthesis-related genes PpPSY, PpPDS, PpZDS, PpLCY-B, PpCHY-B and PpZEP. Nano-Ca also significantly up-regulated the expression of sucrose synthesis related genes PpSUS1 and PpSUS3 in leaves and sucrose transport related genes PpSUT2 and PpSUT4 in stem phloem, promoting the transport of more photosynthetic products to fruits, providing raw materials for carotenoid synthesis, and increasing the content of total sugars and ascorbic acid (Vc). In addition, nano-Ca can also up-regulate the expression levels of PpMYB10.1 and PpUFGT and promote total anthocyanins accumulation in peel. The results of our study will be useful for clarifying how nano-fertilizer improve the fruit quality of nectarine.

Usage of chitosan from Hermetia illucens as a preservative for fresh Prunus species fruits: a preliminary analysis

BackgroundFruit and vegetables are highly perishable. In an era where reducing food waste is absolutely essential, packaging is important for maintaining the postharvest quality of these fresh products. Research is working to reduce the use of synthetic materials, not safe for the environment and human health. In this perspective, chitosan emerges as a viable solution for this purpose, as it is biodegradable, biocompatible and also safe for food application. The growing interest in using insects as a source of chitin has allowed for increased exploitation of insect-based waste products to recover valuable materials, such as biopolymers. The black soldier fly (Hermetia illucens L.) is the most widely reared species in Europe for feed production and waste management.ResultsIn this work, fresh mature apricots (Prunus armeniaca L.), nectarines (Prunus persica vulgaris Mill.) and yellow peaches (Prunus persica var. laevis Gray) were coated with 0.5% and 1% chitosan from the pupal exuviae of Hermetia illucens, applied by spraying and stored at room temperature or 4 °C until they decay. Then, to validate the effectiveness of chitosan as a polymer for fruit preservation, several parameters including pH, TSS and weight loss were evaluated.ConclusionsThe results showed that chitosan derived from the black soldier fly is as effective as or better than the commercially available crustacean chitosan in maintaining more stable some storage parameters in fresh apricots, nectarines and peaches. Thus, insects, especially Hermetia illucens, are confirmed as a viable alternative source of the polymer.Graphical

Correction to: Coniolariella limonispora – a novel causal agent of fruit rot on Prunus persica var. platycarpa

Correction to: Coniolariella limonispora – a novel causal agent of fruit rot on Prunus persica var. platycarpa

Tranzschelia discolor as the Causal Agent of Rust on Nectarine, Peach, and Japanese Plum in Highland Areas of Northern Thailand.

A severe outbreak of rust disease was observed on Prunus species, P. persica (peach), P. persica var. nectarina (nectarine), and P. salicina (Japanese plum) cultivated in northern Thailand in the rainy season. Previous reports have identified the causal agents as Tranzschelia discolor and T. pruni-spinosae based on only morphological characteristics. Thus, the aim of this study was to identify rust fungi of Prunus spp. based on morphology and molecular analyses. Between May and July in 2020 and 2022, 18 isolates were collected from five areas in Chiang Mai and Chiang Rai provinces. Symptoms of rust consisted of cinnamon brown pustules of uredinia that were hypophyllous and visible as pale greenish to chlorotic yellowish angular spots on the upper leaf surfaces. Urediniospore shape, size, and color were similar to T. discolor. Molecular analysis of internal transcribed spacer (ITS) and partial 28S large subunit (LSU) region rRNA genes confirmed the isolates to be T. discolor. This is the first report of P. salicina as a host of T. discolor in Thailand.

Synergy between pre-harvest practices and storage conditions to achieve good quality nectarines and prevent brown rot losses during storage: A modeling framework

Pre- and post-harvest stages are rarely considered together in modeling studies of fruit quality and disease development, despite evident connections between these two fruit life stages in terms of underlying processes.In order to fill this gap, a new modeling framework has been introduced to simulate the effects of pre-harvest practices (irrigation regime and fruit thinning intensity) and storage conditions (temperature and relative humidity) on the development of fruit quality traits during the growing season and storage, fruit yield, and the appearance of brown rot infections during storage. The model was specifically built and calibrated for nectarine (Prunus persica var. nucipersica). A set of performance criteria was defined based on model outputs describing fruit quality (fruit size and sweetness), yield and fruit loss during storage (caused by excessive mass loss or brown rot infections). A sensitivity analysis was then carried out to study the relationships between performance criteria and pre-harvest practices and storage conditions. Finally, the model was used in combination with an optimization algorithm to retrieve the pre- and post-harvest scenarios that maximized fruit quality and quantity, aggregated into a unique performance score. This was done for different storage times and the relative importance assigned to fruit quality criteria. The results revealed that irrigation regime and thinning intensity were significant in defining fruit quality traits, while storage conditions influenced fruit loss during storage. The interactions between pre- and post-harvest conditions were also found to be important when considering the fruit loss related to brown rot infections and the fruit yield at the end of storage. The importance assigned to quality criteria largely affected the optimization outcomes. Thus, the best scenario had moderate water deficit and a low-to-medium thinning intensity when the importance of the fruit sweetness index was high, and well-irrigated regimes and very low thinning intensity when it was lower. The results also indicated a trade-off between quality criteria and, in particular, sweetness and fruit yield. The proposed modeling framework highlighted the fact that the pre- and post-harvest conditions should be considered together because they can influence both fruit quality and quantity, including fruit loss due to brown rot. The model could therefore be used as a tool to enhance dialogue between fruit supply chain actors and to identify solutions to meet their expectations.

Population dynamics of the mite, Tetranychus urticae Koch (acarina: tetranychidae) under acaricide treatment on two varieties of peach and one variety of nectarine in the province of El-Hajeb (Morocco)

The population dynamics of Tetranychus urticae Koch on two varieties of peach (Prunus persica var. Royal Majestic, and Prunus persica var. Kaweah) and one variety of nectarine (Prunus persica var. nucipersica var. Zephyr) were monitored for three years from 2019 to 2022. The results of this study showed that over the course of these three years, infestation peaks occurred in March and declined later in October. For all three varieties, the infestation profile varied from year to year. The Royal Majestic variety was the most infested by T. urticae, with average infestation percentages of 57.06%, 44.11%, and 50.97%, respectively during the three years. As for the two other varieties, the infestation was less pronounced during the three years with average infestation percentages of 31%, 15.42%, and 15.50% on Kaweah and 5.31%, 29.21%, and 26.06% on Zephyr. The results of intra-plant infestation showed that during that during this study periods, the lower stratum was the one with the highest average infestation percentages, with average infestation percentages of 57.29%, 26.08%, and 28.37% respectively on the Royal Majestic, Zephyr, and Kaweah varieties. Concerning the middle stratum, the percentages of infestation are 53.19%, 19.42%, and 19.96% respectively for the Royal Majestic, Zephyr, and Kaweah varieties. For the upper stratum the percentages of infestation are 47.87%, 11.56%, and 9.54% respectively for the Royal Majestic, Zephyr, and Kaweah varieties.

Cytospora paraplurivora sp. nov. isolated from orchards with fruit tree decline syndrome in Ontario, Canada.

A new species of Cytospora was isolated from cankered wood of Prunus spp. during a survey of orchards exhibiting symptoms of fruit tree decline syndrome in southern Ontario, Canada. We found isolates that are morphologically similar to species in the Cytosporaceae family, which is characterized by single or labyrinthine locules, filamentous conidiophores or clavate to elongate obovoid asci and allantoid, hyaline conidia. Multi-gene phylogenetic analysis of ITS, LSU, act and tef1- α showed that the isolates form a distinct clade, sister to Cytospora plurivora. Morphologically, our isolates showed differences in the length of conidia and culture characteristics compared to C. plurivora, suggesting the establishment of a new species. The species is described as Cytospora paraplurivora sp. nov. and placed in the family Cytosporaceae of Diaporthales. Additionally, we sequenced, assembled and characterized the genome of the representative isolate for this new species. The phylogenomic analysis confirms the species order and family level classification. C. paraplurivora sp. nov. has the potential to severely affect stone fruits production, causing cankers and dieback in stressed trees, and eventually leads to tree decline. Pathogenicity tests show that the species is pathogenic to Prunus persica var. persica.

A Ground-based Platform for Reliable Estimates of Fruit Number, Size, and Color in Stone Fruit Orchards

Automatic in-field fruit recognition techniques can be used to estimate fruit number, fruit size, fruit skin color, and yield in fruit crops. Fruit color and size represent two of the most important fruit quality parameters in stone fruit (Prunus sp.). This study aimed to evaluate the reliability of a commercial mobile platform, sensors, and artificial intelligence software system for fast estimates of fruit number, fruit size, and fruit skin color in peach (Prunus persica), nectarine (P. persica var. nucipersica), plum (Prunus salicina), and apricot (Prunus armeniaca), and to assess their spatial and temporal variability. An initial calibration was needed to obtain estimates of absolute fruit number per tree and a forecasted yield. However, the technology can also be used to produce fast relative density maps in stone fruit orchards. Fruit number prediction accuracy was ≥90% in all the crops and training systems under study. Overall, predictions of fruit number in two-dimensional training systems were slightly more accurate. Estimates of fruit diameter (FD) and color did not need an initial calibration. The FD predictions had percent standard errors <10% and root mean square error <5 mm under different training systems, row spacing, crops, and fruit position within the canopy. Hue angle, a color attribute previously associated with fruit maturity in peach and nectarine, was the color attribute that was best predicted by the mobile platform. A new color parameter—color development index (CDI), ranging from 0 to 1—was derived from hue angle. The adoption of CDI, which represents the color progression or distance from green, improved the interpretation of color measurements by end-users as opposed to hue angle and generated more robust color estimations in fruit that turn purple when ripe, such as dark plum. Spatial maps of fruit number, FD, and CDI obtained with the mobile platform can be used to inform orchard decisions such as thinning, pruning, spraying, and harvest timing. The importance and application of crop yield and fruit quality real-time assessments and forecasts are discussed.

PpMAPK6 regulates peach bud endodormancy release through interactions with PpDAM6

The MADS-box (DAM) gene PpDAM6, which is related to dormancy, plays a key role in bud endodormancy release, and the expression of PpDAM6 decreases during endodormancy release. However, the interaction network that governs its regulation of the endodormancy release of flower buds in peach remains unclear. In this study, we used yeast two-hybrid (Y2H) assays to identify a mitogen-activated protein kinase, PpMAPK6, that interacts with PpDAM6 in a peach dormancy-associated SSHcDNA library. PpMAPK6 is primarily located in the nucleus, and Y2H and bimolecular fluorescence complementation (BiFC) assays verified that PpMAPK6 interacts with PpDAM6 by binding to the MADS-box domain of PpDAM6. Quantitative real-time PCR (qRT-PCR) analysis showed that the expression of PpMAPK6 was opposite that of PpDAM6 in the endodormancy release of three cultivars with different chilling requirements (Prunus persica ‘Chunjie’, Prunus persica var. nectarina ‘Zhongyou 5’, Prunus persica ‘Qingzhou peach’). In addition, abscisic acid (ABA) inhibited the expression of PpMAPK6 and promoted the expression of PpDAM6 in flower buds. The results indicated that PpMAPK6 might phosphorylate PpDAM6 to accelerate its degradation by interacting with PpDAM6. The expression of PpMAPK6 increased with decreasing ABA content during endodormancy release in peach flower buds, which in turn decreased the expression of PpDAM6 and promoted endodormancy release.

Comparison of Waterlogging Tolerance of Three Peach Rootstock Seedlings Based on Physiological, Anatomical and Ultra-Structural Changes

Peach (Prunus persica (L.) Batsch) is a typical shallow-rooted fruit plant with a high respiratory intensity and oxygen demand, which makes it highly susceptible to oxygen-deficient soil conditions resulting from waterlogging. Rootstock waterlogging resistance is essential to the performance of cultivated peaches under waterlogging stress. In comparison to Prunus persica var. persica (‘Maotao’, M) and Prunus davidiana (Carr.) C. de Vos (‘Shantao’, S), Prunus persica f. Hossu (‘Hossu’, H) exhibited superior leaf photosynthetic electron transfer efficiency, a higher rate of mycorrhizal fungi infection in both fine roots and mesophyll palisade cells, as well as earlier air cavity formation in both leaf midvein and fine roots under waterlogging stress. Furthermore, under non-waterlogging conditions, Hossu had greater leaf superoxide dismutase (SOD) activity, higher proline content, and a greater content of starch granules in the pith and xylem ray cells of stems and roots than rootstocks M and S. As a result, Hossu’s tolerance to waterlogging may be due to its higher photosynthetic efficiency, improved tissue oxygen permeability, higher energy metabolism, and increased intracellular mycorrhizal fungus infection rates in both root parenchyma cells and mesophyll palisade cells.

Impact of the nicotinic acetylcholine receptor mutation R81T on the response of European Myzus persicae populations to imidacloprid and sulfoxaflor in laboratory and in the field

Sulfoxaflor (Isoclast™ active) is a sulfoximine insecticide that is active on a broad range of sap-feeding insects, including species that exhibit reduced susceptibility to currently available insecticides. Colonies of Myzus persicae (green peach aphid) were established from aphids collected in the field from peach (Prunus persica) and nectarine (Prunus persica var. nucipersica) orchards in France, Italy and Spain. The presence of the nicotinic acetylcholine receptor (nAChR) point mutation R81T was determined for all the colonies. Eight of the 35 colonies collected were susceptible relative to R81T (i.e., R81T absent), three of the colonies were found to be homozygous for R81T while 24 colonies had R81T present in some proportion (heterozygous). Sulfoxaflor and imidacloprid were tested in the laboratory against these M. persicae field colonies, which exhibited a wide range of susceptibilities (sulfoxaflor RR = 0.6 to 61, imidacloprid RR = 0.7 to 986) (resistance ratios, RR) to both insecticides. Although sulfoxaflor was consistently more active than imidacloprid against these field collected M. persicae, there was a statistically significant correlation across all colonies between the RRs for imidacloprid and sulfoxaflor (Pearson's r = 0.939, p < 0.0001). However, when a larger group of the colonies from Spain possessing R81T were analyzed, there was no correlation observed for the RRs between imidacloprid and sulfoxaflor (r = 0.2901, p = 0.3604). Thus, consistent with prior studies, the presence of R81T by itself is not well correlated with altered susceptibility to sulfoxaflor. In field trials, sulfoxaflor (24 and 36 gai/ha) was highly effective (~avg. 88–96% control) against M. persicae, demonstrating similar levels of efficacy as flonicamid (60–70 gai/ha) and spirotetramat (100–180 gai/ha) at 13–15 days after application, in contrast to imidacloprid (110–190 gai/ha) and acetamiprid (50–75 gai/ha) with lower levels of efficacy (~avg. 62–67% control). Consequently, sulfoxaflor is an effective tool for use in insect pest management programs for M. persicae. However, it is recommended that sulfoxaflor be used in the context of an insecticide resistance management program as advocated by the Insecticide Resistance Action Committee involving rotation with insecticides possessing other modes of action (i.e., avoiding rotation with other Group 4 insecticides) to minimize the chances for resistance development and to extend its future utility.

The effect of electrolyzed water on phytopathogenic fungi that infect Prunus persica var. nectarine at post-harvest / Efecto del agua electrolizada en fitopatógenos fungosos que afectan Prunus persica var. nectarine en postcosecha

Postharvest immersion of Prunus persica var. nectarine into electrolyzed water, EW (25.2 ppm of active ingredient), at different time periods of inoculation with pathogens previously isolated from rotted fruits (A, immediately before fruit immersion; B, three hours after fruit immersion and C, three hours before fruit immersion), significantly reduced fruit rotting caused by Botrytis cinerea (A: 40.2%, B: 43.1% and C: 39.1%), or by Monilinia laxa (A: 80.9%, B: 49.8% and C: 46.2%), or by Penicillium. expansum (A: 60.3%, B: 31.9% and C: 49.7%) or by Rhizopus stolonifer (A: 74.4%, B: 60.8% and C: 72.6%). Immersion of fruits into NaClO (100 ppm of active ingredient), showed significant differences with EW treatment: B. cinerea (B/NaClO: 34.5%), M. laxa (A/NaClO: 62.2%; B/NaClO: 36.2% and C/NaClO: 36.2%); P. expansum (C/NaClO: 60.9%) and R. stolonifer (A/NaClO: 81.3%; B/NaClO: 71,2% and C/NaClO: 83.9%) being in most cases, EW better than NaClO. Non inoculated fruits did not show any negative effect after treatment with EW or with NaClO. Also, IC50 values for EW and for NaClO obtained in in vitro tests for mycelia development and spore germination of the different pathogens, correlate well with the in vivo tests. All results suggest that EW can be used as an alternative method to NaClO to control postharvest fungi of Prunus persica var. nectarine fruits , considering that the exposure times and the concentration of EW may be different, depending on the pathogen to be controlled.

Seasonal Qualitative Variations of Phenolic Content in the Stem Bark of Prunus persica var. nucipersica ‐ Implication for the Use of the Bark as a Source of Bioactive Compounds

AbstractThe seasonal variations of the phenolic content in the stem bark of Prunus persica var. nucipersica were analyzed by using high pressure liquid chromatography/electrospray ionization mass spectrometry. Great differences were observed for flavanone 5‐O‐glycosides, rutin and acetylated p‐coumaroylsucrose conjugates containing 0–4 acetyl groups. It is a matter of discussion in which period of the year, May‐August or September‐April, the bark of Prunus persica is the most valuable source of bioactive constituent. If the presence of rutin is desirable, May‐August is the appropriate harvest period, whereas September‐April is appropriate if the presence of flavanone 5‐O‐glycosides is of interest.

Quantifying Evapotranspiration and Drainage Losses in a Semi-Arid Nectarine (Prunus persica var. nucipersica) Field with a Dynamic Crop Coefficient (Kc) Derived from Leaf Area Index Measurements

Quantifying evapotranspiration and drainage losses is essential for improving irrigation efficiency. The FAO-56 is the most popular method for computing crop evapotranspiration. There is, however, a need for locally derived crop coefficients (Kc) with a high temporal resolution to reduce errors in the water balance. The aim of this paper is to introduce a dynamic Kc approach, based on Leaf Area Index (LAI) observations, for improving water balance computations. Soil moisture and meteorological data were collected in a terraced nectarine (Prunus persica var. nucipersica) orchard in Cyprus, from 22 March 2019 to 18 November 2021. The Kc was derived as a function of the canopy cover fraction (c), from biweekly in situ LAI measurements. The use of a dynamic Kc resulted in Kc estimates with a bias of 17 mm and a mean absolute error of 0.8 mm. Evapotranspiration (ET) ranged from 41% of the rainfall (P) and irrigation (I) in the wet year (2019) to 57% of P + I in the dry year (2021). Drainage losses from irrigation (DR_I) were 44% of the total irrigation. The irrigation efficiency in the nectarine field could be improved by reducing irrigation amounts and increasing the irrigation frequency. Future studies should focus on improving the dynamic Kc approach by linking LAI field observations with remote sensing observations and by adding ground cover observations.

Early performance of several Prunus interspecific hybrid rootstocks for Redhaven peach in southern Ontario

A multi-year orchard experiment was established to measure the performance of Rootpac®-R, Rootpac®-20, Rootpac®-40, and Rootpac®-70 rootstocks using ‘Redhaven’ peach (Prunus persica var. persica) as the scion, compared with the ‘Bailey’ peach seedling rootstock, the current industry standard. Tree survival after five years was 79% on Rootpac-40, whereas the remaining rootstocks showed no tree mortality. Tree vigour and canopy height and width were influenced by rootstock genotype beginning the year of planting in 2016. For the first five years of production, Rootpac-70 consistently produced the largest trees based on truck cross-sectional area (TCSA) and by year five, all rootstocks produced trees with similar TCSAs, except for Rootpac-70, which was 38% larger than Bailey. By year five, cumulative yields were greatest on Rootpac-70, which were 10% higher than Bailey; cumulative yields of Rootpac-R, Rootpac-20, and Rootpac-30 were 98%, 89%, and 84% that of Bailey, respectively. Cumulative yield efficiency was significantly influenced by rootstock although the magnitude of the differences was small and likely of insignificant commercial importance. Rootpac-40 consistently produced the largest fruit. These results are only reflective of the orchard establishment years and additional data are required before peach producers can make fully informed decisions concerning the rootstocks evaluated in this study for their orchard systems. However, at this juncture, all the Rootpac rootstocks evaluated in this study are likely to impart excessive vigour to be used in a higher density system and offer little advantage over Bailey.

Transcriptional analysis of the response of nectarine fruit to low-temperature stress in cold storage

ABSTRACT Nectarine (Prunus persica var. nectarina) is a sub-tropical fruit tree with strong cold sensitivity. In this study, flesh of nectarine (Shuguang) was used to determine the difference in transcriptional data before and after chilling injury under storage. In addition, genes responses involved in nectarine acclimation to cold stress were also explored. Results of the current study showed that nectarine was found to be more susceptible to chilling injury during storage at 5°C than at 0°C, and differentially expressed genes (DEGs) were concentrated in the late stage of low-temperature storage where chilling injury symptoms appeared at the end of the experiment. The key genes related to low-temperature response were associated with post-harvest biological processes. DEGs were annotated on the metabolic pathways of cold regulation signal transduction, cold resistance physiological metabolism and cold resistance-related protein synthesis. Moreover, the expression of genes related to cold stress such as plant hormone signal transduction element such as Auxin-responsive protein, transcription factors responding to cold stress such as WRKY transcription factor and genes related to maintaining membrane stability and regulating physiological metabolism such as proline dehydrogenase was more pronounced when nectarine was stored at 5°C than at 0°C. Overall, these findings showed that alteration in chilling temperature has substantial impact on the transcription levels associated with cold resistance pathway during the low-temperature storage of nectarine and thus promotes chilling injury disorders in nectarine.

Influence of host plants on the development, survivorship, and fecundity of the summer fruit tortrix moth, Adoxophyes orana (Lepidoptera: Tortricidae)

AbstractThe summer fruit tortrix moth Adoxophyes orana is a seriously damaged leaf roller pest for fruit trees. In this study, we evaluated the effect of five host plants (apple, Malus domestica B.; peach, Prunus persica var. nectarina; apricot, Armeniaca vulgaris Lam.; mulberry, Morus alba L.; and jujube, Ziziphus jujuba M.) on the development, survival, and fecundity of A. orana under laboratory conditions. Results showed that the development times of A. orana on jujube were significantly longer than those on the other four plants. The preimaginal survival rate was influenced by the host plants, which were fed during the larval stage, and with the highest on peach, followed by apple, apricot, and mulberry, and with the lowest on jujube. Adult females from larvae reared on apricot laid the greatest numbers of eggs (318.11 eggs per female), while that on apple, jujube, and mulberry was smaller, and no significant difference was observed among them. The highest intrinsic rate of increase (rm) was observed on peach and apricot; these two fruit trees were considered to be the most suitable host plant for A. orana because of the shorter developmental duration, higher survival rate, and the highest fecundity.