Apple Cultivars Research Articles

Dormancy dynamics and cold hardiness of apple trees grown in a mild winter region

In temperate fruit plants, climate is the main factor correlating changes in plant physiology, mainly those related to entry and exit from dormancy and cold hardiness. Acclimation to cold and its relationship with dormancy are still unknown in areas with a subtropical climate. Therefore, this study aimed to investigate the dormancy dynamics and their interaction with the cold hardiness of different tissues of apple cultivars with different chilling requirements in two cultivation sites in a mild winter region in southern Brazil. The analyses were conducted from 2018 to 2022. The cultivars Gala, Fuji, and Eva were used in two environments with different altitudes. The dormancy dynamics were analyzed using the single-node cutting test, and the cold hardiness of the different tissues of each genotype was evaluated through electrolyte leakage in laboratory freezing tests. Cultivars Gala and Fuji had a greater depth of dormancy than Eva. Plants grown in orchards with higher chill accumulation had a greater depth of dormancy. Cold hardiness varied among cultivars, with the Eva cultivar having the lowest cold hardiness in mid-winter. The tissues (bud, bark, and wood) had different cold hardiness in early winter, with wood having the greatest cold hardiness, followed by bud and bark. As Eva did not go into deep dormancy, a superficial and short acclimation to cold was observed, in addition to rapid sprouting, even in winter. This condition predisposed it to cold damage to tissues in the pre-sprouting period. In this study, we found that maximum cold hardiness occurred after the end of the deep-endodormancy phase. Deacclimation of all cultivars occurred very quickly.

Irrigation Targeted to Provoke Ejection of Ascospores of Venturia inaequalis Shortens the Season for Ascospore Release and Results in Less Apple Scab.

Trials were carried out in apple orchards of Emilia-Romagna and Trentino-Alto Adige in northern Italy to investigate the effects of sprinkler irrigation on possible reduction in inoculum and subsequent disease pressure of Venturia inaequalis, the ascomycete causing apple scab. In spring, volumetric spore traps were placed above apple leaf litter containing pseudothecia with ascospores of the fungus. Pseudothecia matured more rapidly in irrigated plots, and 95% of the total number of spores trapped in a season was reached on average 164 degree days (base temperature 0°C) earlier in irrigated compared with nonirrigated plots. On average for seven location/year combinations, more than 50% of the ascospores were trapped following irrigations carried out for 2 h on sunny days before a forecasted rainfall. Subsequently, a much lower number of spores were trapped on rainy days following irrigation. Field trials with scab-susceptible apple cultivars were carried out in the two regions to evaluate the efficacy of sprinkler irrigation on disease. Irrigated and nonirrigated plots were either treated with different fungicide control strategies or not treated. Irrigation significantly reduced the incidence of apple scab at both sites, and the overall number of infected leaves and fruit was reduced by more than 50%. Midday sprinkler irrigation can significantly reduce the inoculum pressure of V. inaequalis in apple orchards. This may be a sustainable management strategy, especially in areas with extended dry periods.

The potential range of west Asian apple species Malus orientalis Uglitzk. under climate change

The wild relatives of cultivated apples would be an ideal source of diversity for breeding new varieties, which could potentially grow in diverse habitats shaped by climate change. However, there is still a lack of knowledge about the potential distribution of these species. The aim of the presented work was the understand the impacts of climate change on the potential distribution and habitat fragmentation of Caucasian crab apple (Malus orientalis Uglitzk.) and the designation of areas of high interest according to climatic conditions. We used the MaxEnt models and Morphological-Spatial Analysis (MSPA) to evaluate the potential distribution, suitability changes, habitat fragmentation, and connectivity throughout the species range in Turkey, Armenia, Georgia, Russia, and Iran. The results revealed that the potentially suitable range of M. orientalis encompasses 858,877 km², 635,279 km² and 456,795 km² under the present, RCP4.5 and RCP8.5 scenario, respectively. The range fragmentation analysis demonstrated a notable shift in the edge/core ratio, which increased from 50.95% in the current scenario to even 67.70% in the future. The northern part of the range (Armenia, northern Georgia, southern Russia), as well as the central and western parts of Hyrcania will be a core of the species range with suitable habitats and a high connectivity between M. orientalis populations and could work as major refugia for the studied species. However, in the Zagros and central Turkey, the potential range will shrink due to the lack of suitable climatic conditions, and the edge/core ratio will grow. In the southern part of the range, a decline of M. orientalis habitats is expected due to changing climatic conditions. The future outlook suggests that the Hyrcanian forest and the Caucasus region could serve as important refuges for M. orientalis. This study helps to understand spatial changes in species’ range in response to climate change and can help develop conservation strategies. This is all the more important given the species’ potential use in future breeding programs aimed at enriching the gene pool of cultivated apple varieties.

Ecological and economic evaluation of modern systems for apple tree protection from codling moth

This work substantiates the transition to biorational systems of plantation protection using low-toxic preparations to ensure high-quality yields. Regularities in the development of codling moth in Krasnodar Krai are revealed. During the period of 2021–2023, a 30% increase in the expenditures on protective measures in horticultural organizations of Krasnodar Krai was established. As a result, the production costs grew by an average of 17%, decreasing the entire efficiency of fruit production. This explains the need to develop modern protection systems for perennial plantations. Differentiated approaches to apple-tree protection from pests (on the example of codling moth), which are based on application of low-toxic chemical and biorational preparations according to phytophage development stages, are reviewed. An integrated system for protection of industrial fruit plantations in the Krasnodar Krai against coddling moth is proposed. The advantages of the proposed system over the existing approaches that apply highly toxic chemicals are described. These relate to the possibility of introducing flexible changes in protective measures in accordance with phytosanitary characteristics of orchards, including activation of local apple varieties and use of agrotechnical and biological methods based on toxicological monitoring. An ecological and economic evaluation of the integrated system of fruit plantation protection from codling moth is provided. This system enables a reduction in the background pesticide content in food chains (a 2-fold and 5-fold decrease in soils and fruits, respectively), a 1.3-fold reduction in pesticide load, the preservation of yield by more than 98% while complying with the regulations of ecological agrocenosis safety regulations, a 1.5-fold reduction in production costs, and a 10.5% increase in the product profitability.

Influence of pre-harvest calcium application on the concentration and distribution of ascorbic acid and mineral content in apple cultivars at harvest and during storage

This study investigated the effects of pre-harvest calcium (Ca) application on apple fruit ascorbic acid (AsA) concentration and mineral contents in the cultivars ‘Braeburn’, ‘Fräulein’, ‘Pinova’, ‘Topaz’ and ‘Elstar’, and core browning (CB) susceptibility in ‘Braeburn’ and ‘Fräulein’ during controlled atmosphere (CA) storage (1 °C, 1 kPa O2 plus ≤ 1 kPa CO2). Approximately eight pre-harvest Ca applications were applied during the growing season for ‘Braeburn’ and ‘Fräulein’ cultivars and one application in “spring” for ‘Pinova’, ‘Topaz’ and ‘Elstar’. In addition, data from five consecutive harvest seasons was used to assess the relationship among AsA, mineral content, and CB for ‘Braeburn’. Results showed that the impact of pre-harvest Ca was variable among cultivars; fruit Ca concentration was increased and the K/Ca ratio was reduced only in ‘Fräulein’ fruit, and AsA was increased only in ‘Braeburn’ fruit, especially in the inner cortex tissue where CB occurs. For ‘Pinova’, ‘Elstar’ and ‘Topaz’, Ca concentration was slightly higher in untreated fruit compared to Ca-treated fruit (p < 0.07). AsA increased after storage, remaining higher in ‘Braeburn’ fruit treated with Ca, especially in the outer cortex tissue. Pre-harvest Ca reduced CB in ‘Fräulein’, but CB incidences in ‘Braeburn’ were too severe (> 84%) and unaffected by Ca application. Analysis of the data from five consecutive harvest seasons showed that ‘Braeburn’ CB incidence related positively with Ca (r = 0.97, p < 0.05) and negatively with the AsA/Ca ratio (r = −0.71, p > 0.05). Our results suggest that the positive effect of pre-harvest Ca application in reducing CB incidence in ‘Braeburn’ apple, as reported by previous studies on ‘Braeburn’ apple, may be associated with increased AsA concentration, possibly due to higher synthesis and/or reduced degradation, rather than due to higher total fruit Ca concentration.

A non-invasive method for phenotyping scab-tolerant apple plants using volatile organic compounds.

One of the most devastating diseases of apples is scab, caused by the fungus Venturia inaequalis. Most commercial apple varieties are susceptible to this disease; only a few are resistant. Breeding approaches are being used to develop better apple varieties that are resistant to scab. Volatile organic compounds (VOCs) contribute greatly to a plant's phenotype, and their emission profile largely depends on the genotype. In the non-destructive phenotyping of plants, VOCs can be used as biomarkers. In this study, we assessed non-destructively the scab tolerance potential of resistant (cv. 'Prima') and susceptible (cv. 'Oregon Spur') apple cultivars by comparing their major leaf VOC compositions and relative proportions. A comparison of the leaf VOC profiles of the two cultivars revealed 16 different VOCs, with cis-3-hexenyl acetate (3HA) emerging as a biomarker of cultivar differences. V. inaequalis growth was significantly inhibited in vitro by 3HA treatment. 3HA was significantly effective in reducing scab symptoms on V. inaequalis-inoculated leaves of 'Oregon Spur.' The resistant cultivar 'Prima' also exhibited higher lipoxygenase (LOX) activity and α-linolenic acid (ALA) levels, suggesting that V. inaequalis resistance is linked to LOX activity and 3HA biosynthesis. This study proposes 3HA as a potential biomarker for rapid non-destructive screening of scab-resistant apple germplasm of 'Prima' based on leaf VOCs.

First report of Nectria dematiosa causing European canker of apple in India

AbstractNectria dematiosa exhibiting orange red colour perithecia on stems and branches of young and old apple trees were reported under field conditions during 2020 and 2021. Reddish discoloration followed by papery appearance of stem and branches were the characteristic symptoms observed. Ascomata were non‐papillate, surface irregular comprising numerous cylindrical to narrowly clavate asci. Ascospores were ellipsoidal to fusiform, straight or slightly curved, hyaline with 0 to 1‐septa. Richard and Royal Delicious variety of apple were more susceptible with moderate to high severity of the European canker. Based on nucleotide homology and phylogenetic analysis, the pathogen was confirmed as N. dematiosa (accession no. OQ152022). To the best of our knowledge, this is the first report of N. dematiosa causing European canker of apple in India.

An Apple a Day Keeps the Gray Mold Away

Most consumers dispose of rotten food without a second thought; however, they also throw away a dynamic group of plant pathogens that can be utilized for inquiry-driven investigations into host/pathogen interactions. Botrytis cinerea is a common necrotrophic fungus that can infect most plants but causes substantial losses to the grape and fresh berry industries. Because most store-bought strawberries eventually succumb to this pathogen (due to the presence of spores from the field or packing facility), they are a dependable source of fungal inoculum to test novel hypotheses about the nature of disease. Across the produce aisle, apples are a diverse, well-characterized, and susceptible host population that enables students to construct individualized experiments about the nature of disease with adequate replication for meaningful analysis. This experimental protocol will outline how to conduct an infection assay with B. cinerea and commercially available apple varieties for students to develop their own experiments, inoculate their own plants, and analyze their own data to answer important questions about how pathogens cause disease.

1-Methylcyclopropene Improves the Postharvest Physiological Characteristics and Fruit Quality of ‘Colorpple’ and ‘Manhong’ Apple Cultivars during Storage at Warm and Cold Temperatures

1-Methylcyclopropene Improves the Postharvest Physiological Characteristics and Fruit Quality of ‘Colorpple’ and ‘Manhong’ Apple Cultivars during Storage at Warm and Cold Temperatures

Comprehensive Analysis of Flowering Patterns in One-Year-Old Long Shoots of Apple Cultivars with Contrasted Bearing Habits

Before developing orchard management strategies, it is crucial to conduct architectural analysis at the shoot level for the specific type of fruit to be grown. The objective of this study was to analyze flowering patterns in 1-year-old long shoots of three apple cultivars ('Amasya,' 'Braeburn,' and 'Granny Smith') with different bearing behaviors. This analysis aimed to gain a better understanding of their growth dynamics and reproductive activities. The shoot was divided into three consecutive zones (proximal, median, and distal) based on node number. When comparing the number of floral and vegetative buds in the three zones along the shoot, less contrast was observed between alternate-bearing ('Amasya') and regular-bearing cultivars ('Braeburn' and 'Granny Smith'). However, a notable difference in floral bud quality variables was evident in shoot zones between biennial-bearing and regular-bearing cultivars. In 'Braeburn' and 'Granny Smith' with a regular bearing habit, floral bud quality variables remained stable along the shoot. In contrast, 'Amasya' shoots exhibited a gradual increase in floral bud quality from the proximal zone towards the distal zone. This study underscores the significance of floral bud quality, especially the properties of spur leaves along the shoot, in ensuring optimal and consistent productivity. Finally, with the exception of internode length, morphometric traits did not significantly differ between cultivars when considering the entire shoot. However, these differences became apparent when examining successive zones along the shoot.

A comparative study of distinguishing apple cultivars and a clone based on features of selected fruit parts and leaves using image processing and artificial intelligence

This study aimed to identify the most useful white-fleshed apple samples to distinguish apple cultivars and a clone. Whole apples, apple slices, seeds, and leaves belonging to ‘Free Redstar’, clone 118, ‘Ligolina’, ‘Pink Braeburn’, and ‘Pinokio’ were imaged using a digital camera. The texture parameters were extracted from images in color channels L, a, b, R, G, B, X, Y, Z, U, V, and S. The classification models were built using traditional machine learning algorithms. Models developed using selected image seed textures allowed the classification of apple cultivars and a clone with the highest average accuracy of up to 97.4%. The apple seeds ‘Free Redstar’ were distinguished with the highest accuracy, equal to 100%. Machine learning models built based on the textures of apple skin allowed for the clone and cultivar classification with slightly lower correctness, reaching 94%. Meanwhile, the average accuracies for models involving selected flesh and leave textures reached 86.4% and 88.8%, respectively. All the most efficient models for classifying individual apple fruit parts and leaves were developed using Multilayer Perceptron. However, models combining selected image textures of apple skin, slices (flesh), seeds, and leaves produced the highest average accuracy of up to 99.6% in the case of Bayes Net. Thus, it was found that including features of different parts of apple fruit and apple leaves in one model can allow for the correct distinguishing of apples in terms of cultivar and clone.

Nutrient Content and in Vitro Digestibility of Apple Pomace Derived from Three Different Apple Cultivars

This study focused on evaluating the nutritional characteristics and in vitro true digestibility of apple pomace derived from three apple cultivars: Golden Delicious, Starking, and Granny Smith (Malus domestica Borkh). These apple cultivars were sourced from the local market in Nigde, Turkiye. Statistical analyses, including one-way analysis of variance (ANOVA) and Duncan's test, were employed to assess variations among the apple pomace samples. Results indicated that, except for in vitro true digestibility, there were no significant variations in the chemical composition and total phenolic matter contents among the apple pomaces (P&gt;0.05). However, Granny Smith apple pomace exhibited distinct features, such as higher neutral detergent fiber content (29.80%), elevated crude protein levels (5.09%) and substantial acid detergent fiber (25.30%) values. In contrast, Starking apple pomace displayed superior air-dry matter (27.24%), while Golden Delicious showcased enhanced dry matter (95.3%) and ash content (2.00%). Regarding total phenolic matter contents, Granny Smith excelled with 112.4 mg GAE/100g, outperforming Starking (103 mg GAE/100g) and Golden Delicious (75.8 mg GAE/100g). Crucially, Starking demonstrated superior in vitro true digestibility, with values reaching 92.36% (as received) and 92.23% (dry matter). Granny Smith, in comparison to Golden Delicious and Starking, displayed significantly different neutral detergent fiber digestibility (P&lt;0.05). Starking apple pomace exhibit the highest overall digestibility among the apple pomaces analysed in this study, hence recommended for use in ruminant nutrition. These findings have implications for the potential utilization of apple pomace in diverse applications, given the diverse nutritional profiles of these cultivars.

Impacts of N-P-K-Mg Fertilizer Combinations on Tree Parameters and Fungal Disease Incidences in Apple Cultivars with Varying Disease Susceptibility.

Adequate mineral fertilization helps to ensure optimal tree growth, fruit development, and predictable yield of apple trees. This 7-year study (2016-2022) aims to investigate the effect of nitrogen (N), phosphorus (P), potassium (K), and magnesium (Mg) fertilizer combinations (NP, NPK, NPKMg, and control) on eight parameters (trunk cross-sectional area-TCSA; fruit yield-FY; number of fruit per tree-FNT; crop load-CL; fruit diameter-FD; fruit weight-FW; fruit scab incidence-FSI; and powdery mildew incidence on shoot-PMIS) on the cultivars (cvs) 'Golden Reinders' (disease susceptible) and 'Pinova' (scab and mildew tolerant). In the 7-year period, TCSA values continuously increased for both cultivars over the years. Fertilizer treatments showed significant differences on TCSA but the effect varied greatly annually among fertilizer treatments. Fertilizer treatments had increasing effects on FY and FNT in 2018 and 2022, on CL in 2018, on FD in 2018 and 2019, and on FW in 2016 and 2018 in both cultivars compared to the control treatment. FSI values were the lowest in the NPKMg treatment for cv. 'Golden Reinders' in 2016, 2017, and 2022; for cv. 'Pinova' in 2016; PMIS values for cv. 'Golden Reinders' in 2017, 2018, 2021, and 2022; and for cv. 'Pinova' in 2018. Correlation and regression analyses revealed strong and significant (p = 0.05) relationships between FNT versus (vs.) TCSA, FNT vs. FY, FW vs. TCSA, CL vs. FY, FW vs. FD, and FSI vs. FW. In conclusion, our study showed that multiyear application of fertilizer combinations can successfully increase TCSA and yield parameters as well as reduce fungal disease incidences, especially on the disease-susceptible cultivar in sandy soil with moderate fertility, under Central-European continental climate conditions.

Transposable elements in Rosaceae: insights into genome evolution, expression dynamics, and syntenic gene regulation.

Transposable elements (TEs) exert significant influence on plant genomic structure and gene expression. Here, we explored TE-related aspects across 14 Rosaceae genomes, investigating genomic distribution, transposition activity, expression patterns, and nearby differentially expressed genes (DEGs). Analyses unveiled distinct long terminal repeat retrotransposon (LTR-RT) evolutionary patterns, reflecting varied genome size changes among nine species over the past million years. In the past 2.5 million years, Rubus idaeus showed a transposition rate twice as fast as Fragaria vesca, while Pyrus bretschneideri displayed significantly faster transposition compared with Crataegus pinnatifida. Genes adjacent to recent TE insertions were linked to adversity resistance, while those near previous insertions were functionally enriched in morphogenesis, enzyme activity, and metabolic processes. Expression analysis revealed diverse responses of LTR-RTs to internal or external conditions. Furthermore, we identified 3695 pairs of syntenic DEGs proximal to TEs in Malus domestica cv. 'Gala' and M. domestica (GDDH13), suggesting TE insertions may contribute to varietal trait differences in these apple varieties. Our study across representative Rosaceae species underscores the pivotal role of TEs in plant genome evolution within this diverse family. It elucidates how these elements regulate syntenic DEGs on a genome-wide scale, offering insights into Rosaceae-specific genomic evolution.

Profiling and optimized extraction of bioactive polyphenolic compounds from young, red-fleshed apple using eco-friendly deep eutectic solvents

Red-fleshed apple cultivars with an enhanced content of polyphenolic compounds have attracted increasing interest due to their promising health benefits. Here, we have analysed the polyphenolic content of young, red-fleshed apples (RFA) and optimised extraction conditions of phenolics by utilising natural deep eutectic solvents (NDES). We also compare the antioxidant, neuroprotective and antimicrobial activities of NDES- and methanol-extracted phenolics from young RFA. High-performance liquid chromatography coupled to high-resolution mass spectrometry (HPLC-HRMS) was used for phenolics identification and quantification. Besides young RFA, ripe red-fleshed, young and ripe white-fleshed apples were analysed, revealing that young RFA possess the highest phenolic content (2078.4 ± 4.0 mg gallic acid equivalent/100 g), and that ripe white-fleshed apples contain the least amount of phenolics (545.0 ± 32.0 mg gallic acid equivalent/100 g). The NDES choline chloride-glycerol containing 40 % w/w H2O gave similar yields at 40 °C as methanol. In addition, the polyphenolics profile, and bioactivities of the NDES extract from young RFA were comparable that of methanol extracts. Altogether, our data show that NDES extracts of young RFA are a promising source of bioactive polyphenolics with potential applications in diverse sectors, e.g., for functional food production, smart material engineering and natural therapies.

Metabolomics on Apple (Malus domestica) Cuticle-Search for Authenticity Markers.

The profile of secondary metabolites present in the apple cuticular layer is not only characteristic of a particular apple cultivar; it also dynamically reflects various external factors in the growing environment. In this study, the possibility of authenticating apple samples by analyzing their cuticular layer extracts was investigated. Ultra-high-performance liquid chromatography coupled with high-resolution tandem mass spectrometry (UHPLC-HRMS/MS) was employed for obtaining metabolomic fingerprints. A total of 274 authentic apple samples from four cultivars harvested in the Czech Republic and Poland between 2020 and 2022 were analyzed. The complex data generated, processed using univariate and multivariate statistical methods, enabled the building of classification models to distinguish apple cultivars as well as their geographical origin. The models showed very good performance in discriminating Czech and Polish samples for three out of four cultivars: "Gala", "Golden Delicious" and "Idared". Moreover, the validity of the models was tested over several harvest seasons. In addition to metabolites of the triterpene biosynthetic pathway, the diagnostic markers were mainly wax esters. "Jonagold", which is known to be susceptible to mutations, was the only cultivar for which an unambiguous classification of geographical origin was not possible.

Comparing visible and near infrared ‘point’ spectroscopy and hyperspectral imaging techniques to visualize the variability of apple firmness

In this work, visible and near-infrared ‘point’ (Vis-NIR) spectroscopy and hyperspectral imaging (Vis-NIR-HSI) techniques were applied on three different apple cultivars to compare their firmness prediction performances based on a large intra-variability of individual fruit, and develop rapid and simple models to visualize the variability of apple firmness on three apple cultivars. Apples with high degree of intra-variability can strongly affect the prediction model performances. The apple firmness prediction accuracy can be improved based on the large intra-variability samples with the coefficient variation (CV) values over 10%. The least squares-support vector machine (LS-SVM) models based on Vis-NIR-HSI spectra had better performances for firmness prediction than that of Vis-NIR spectroscopy, with the with the Rc2 over 0.84. Finally, The Vis-NIR-HSI technique combined with least squares-support vector machine (LS-SVM) models were successfully applied to visualize the spatial the variability of apple firmness.

Mango headspace volatiles trigger differential responses of the mango fruit fly Ceratitis cosyra and its parasitoids

Before the introduction of Bactrocera dorsalis (Hendel) to sub-Saharan Africa, Ceratitis cosyra (Walker) was economically the most important pest in mango farming. Its native natural enemy, the solitary parasitoid Psyttalia cosyrae (Wilkinson), played a crucial role in C. cosyra bio-control, later complemented by the exotic parasitoids Diachasmimorpha longicaudata (Ashmead) and Fopius arisanus (Sonan) among Integrated Pest Management (IPM) systems. To understand the in situ mango-C. cosyra-parasitoid tritrophic interaction, we assessed the responses of the fruit fly and the three parasitoids to headspace volatiles from various mango conditions. These conditions included non-infested mature unripe mangoes, C. cosyra-infested mangoes, 7th- and 9th-day post-infestation mangoes, non-infested ripe mangoes of three varieties (Kent, Apple, and Haden), and clean air (blank). We also compared the fruit fly's performance in the mango varieties and identified the chemical profiles of mango headspace volatiles. Ceratitis cosyra was attracted to both infested and non-infested mangoes (66–84 % of responsive C. cosyra) and showed superior performance in Kent mango (72.1 % of the 287 puparia recovered) compared to Apple and Haden varieties. Fopius arisanus displayed a stronger attraction to the volatiles of C. cosyra-infested mangoes (68–70 %), while P. cosyrae and D. longicaudata were significantly attracted to the 9th-day post-infestation mangoes (68–78 %) compared to non-infested mango volatiles. Gas chromatography-mass spectroscopy showed substantial quantitative and qualitative differences in volatile profiles among mango treatments. Esters predominated in non-infested ripe, 7th- and 9th-day post-infestation mangoes, while monoterpenes and sesquiterpenes were most dominant in the other treatments. The in situ experiments underscored varying preferences of the species for mango headspace volatiles and their subsequent treatments. These results provide valuable insights for further exploration, specifically in identifying the key volatiles responsible for species responses, to facilitate the development of applicable selective semiochemicals for managing species of African fruit fly.

The Expression of Key Ethylene and Anthocyanin Biosynthetic Genes of 'Honeycrisp' Apples Subjected to the Combined Use of Reflective Groundcovers and Aminoethoxyvinylglycine in the Mid-Atlantic US.

The decreased profitability of important apple cultivars, such as 'Honeycrisp', results from the poor red skin coloration and high fruit drop in the mid-Atlantic US. Apple red skin coloration is determined by the anthocyanin concentration. Reflective groundcovers promote red skin coloration, whereas aminoethoxyvinylglycine (AVG) decreases the ethylene production and fruit drop, thus reducing the coloration. Although our previous study showed that combinations of these practices impact the fruit quality and color, research is lacking regarding their effects at the gene and metabolite levels. In this work, for two years, we compared the differences in the internal ethylene concentration (IEC), red skin coloration, fruit drop, transcript accumulation of key ethylene and anthocyanin biosynthetic pathway-related genes, and total anthocyanin concentration of 'Honeycrisp' apples. The fruit was treated with combinations of reflective groundcover (Extenday) and AVG (130 mg L-1) and was assessed throughout ripening. Extenday-only-treated fruit displayed the highest upregulation of ethylene and anthocyanin biosynthetic-related genes and of total anthocyanins, exceeding 50% blush, while boosting the IEC. In contrast, AVG significantly decreased the expression of key ethylene and anthocyanin biosynthetic-related genes and total anthocyanins, thus preventing apples from reaching 50% blush, while also decreasing the IEC and fruit drop. The combination of Extenday x AVG fine-tuned the transcript accumulation of ethylene and anthocyanin biosynthetic-related genes as well as the total anthocyanins, allowing the 'Honeycrisp' fruit to exceed 50% blush, while increasing the IEC moderately and reducing the fruit drop (as compared to Extenday-only and control), thus enhancing the fruit economic value.

Effects of Different Pre-Harvest Bagging Times on Fruit Quality of Apple.

Pre-harvest bagging can improve fruit color and protects against diseases. However, it was discovered that improper bagging times could lead to peel browning in production. Using the Ruixue apple variety as the research model, a study was conducted to compare the external and internal quality of fruits bagged at seven different timings between 50 and 115 days after full bloom (DAFB). Our findings indicate that delaying the bagging time can reduce the occurrence of peel browning in Ruixue apples. Compared to the control, the special bag reduced the browning index by 22.95%. However, the fruit point index of Ruixue fruits increased by 65.05% at 115 DAFB compared to 50 DAFB when bagging was delayed. The chlorophyll content of Ruixue fruits in special bags generally increased and then decreased, with the highest chlorophyll content of Ruixue fruits in special bags at 90 DAFB, which was 26.02 mg·kg-1. When the bagging process was delayed, the soluble solids, total phenols, and flavonoids content in the fruits increased, while the number of control volatiles decreased by 10. After two years of testing, results show that using special fruit bags at 90 DAFB bagging can significantly improve the fruit quality of Ruixue apple.