Apple Fruit Quality Research Articles

The Mechanism of Ovule Abortion in Self-Pollinated 'Hanfu' Apple Fruits and Related Gene Screening.

Apples exhibit S-RNase-mediated self-incompatibility and typically require cross-pollination in nature. 'Hanfu' is a cultivar that produces abundant fruit after self-pollination, although it also shows a high rate of seed abortion afterwards, which greatly reduces fruit quality. In this study, we investigated the ovule development process and the mechanism of ovule abortion in apples after self-pollination. Using a DIC microscope and biomicroscope, we found that the abortion of apple ovules occurs before embryo formation and results from the failure of sperm-egg fusion. Further, we used laser-assisted microdissection (LAM) cutting and sperm and egg cell sequencing at different periods after pollination to obtain the genes related to ovule abortion. The top 40 differentially expressed genes (DEGs) were further verified, and the results were consistent with switching the mechanism at the 5' end of the RNA transcript (SMART-seq). Through this study, we can preliminarily clarify the mechanism of ovule abortion in self-pollinated apple fruits and provide a gene reserve for further study and improvement of 'Hanfu' apple fruit quality.

Epigenomic mechanism regulating the quality and ripeness of apple fruit with differing harvest maturity.

Harvest maturity significantly affects the quality of apple fruit in post-harvest storage process. Although the regulatory mechanisms underlying fruit ripening have been studied, the associated epigenetic modifications remain unclear. Thus, we compared the DNA methylation changes and the transcriptional responses of mature fruit (MF) and immature fruit (NF). There were significant correlations between DNA methylation and gene expression. Moreover, the sugar contents (sucrose, glucose, and fructose) were higher in MF than in NF, whereas the opposite pattern was detected for the starch content. The expression-level differences were due to DNA methylations and ultimately resulted in diverse fruit textures and ripeness. Furthermore, the higher ethylene, auxin, and abscisic acid levels in MF than in NF, which influenced the fruit texture and ripening, were associated with multiple differentially expressed genes in hormone synthesis, signaling, and response pathways (ACS, ACO, ZEP, NCED, and ABA2) that were regulated by DNA methylations. Multiple transcription factor genes involved in regulating fruit ripening and quality via changes in DNA methylation were identified, including MIKCC-type MADS-box genes and fruit ripening-related genes (NAP, SPL, WRKY, and NAC genes). These findings reflect the diversity in the epigenetic regulation of gene expression and may be relevant for elucidating the epigenetic regulatory mechanism underlying the ripening and quality of apple fruit with differing harvest maturity.

Effects of Organic Substitution on the Yield and Quality of Apples and Residual Nitrate-N Leaching in Soil

The substitution of chemical nitrogen (N) fertilizer with organic fertilizer (organic substitution, OS) is increasingly applied in crop production, due to its environmentally friendly characteristics, low price, and high crop and soil improvement efficacies. Here, we studied the effects of chemical N fertilizer with organic fertilizer treatment at different proportions (no organic substitution (NOS), 20% (OS-20), 40% (OS-40), 60% (OS-60), 100% (OS-100), and 200% (OS-200, double the organic fertilizer application amount of OS-100) on the yield and quality of apples in the Shanxi Province of China. The results revealed that, compared to the NOS, the total apple yields of OS treatments, especially the OS-60 and OS-100 treatments, decreased. However, all OS treatments, except OS-200, increased the yield of large-sized fruits (transverse diameter ≥ 85 mm) and the mean mass of apple fruits, and significantly decreased yield of small-sized fruits (transverse diameter < 75 mm). All OS treatments, especially OS-40, promoted the total sugar and vitamin C (Vc) contents and fruit hardness of apples, and OS-40, OS-60, and OS-200 resulted in significantly decreased titratable acid contents in apples. The influence of organic substitutions on soil quality was further investigated in a two-year field experiment. The results showed that the influence of organic substitution on soil chemical properties differed between the two years. Notably, 40% OS increased the soil organic carbon (SOC) content and the C/N ratio in the upper 20 cm of the soil in both years. Additionally, OS treatments reduced the residual nitrate (NO3−)-N (RN) content in deep soil layers, suggesting that OS has the potential to alleviate N leaching. Moreover, redundancy analysis (RDA) of the soil, fruit yield, and fruit quality parameters revealed that the SOC content in the 0–20 cm soil layer and the RN content in the 0–100 cm soil layer had the greatest impact on the fruit quality and yield variables, respectively. This study showed that the proper substitution (40%) of chemical N fertilizer with organic fertilizer could improve the yield of large-sized fruits, the mean mass and fruit quality of apples, and soil chemical properties. Our study will provide a basis for rational organic substitution in apple orchards.

The Effect of Nitrogen Reduction and Applying Bio-Organic Fertilisers on Soil Nutrients and Apple Fruit Quality and Yield

In this study, we investigated the effect of partially substituting inorganic nitrogen with bio-organic fertiliser on the ‘Tianhong2’ Fuji apple planting in Xinjiang. Bio-organic fertiliser was applied, and nitrogen was reduced by 20% (T2), 40% (T3), and 60% (T4) during the blooming and fruit expansion periods with conventionally fertilised fields used as control (T1); soil nutrient, soil enzyme activity, leaf nutrients, fruit quality, and yield were measured. The total nitrogen (TN), total phosphorus (TP), total potassium (TK), total calcium (TCa), available phosphorus (AP), available potassium (AK), and soil organic matter (SOM) contents, as well as the soil catalase (S-CAT), soil uretrase (S-UE), soil saccharase (S-SC), and soil nitrate reductase (S-NR) activities, significantly increased in the experimental soils compared with those in T1. In addition, TP, TCa, and total magnesium (TMg) content in apples significantly increased. Compared to T1, the T2 and T3 treatments significantly improved the fruit yield and quality, increasing the sugar–acid ratio, soluble protein, soluble sugar, peel carotenoid, and anthocyanin content and reducing peel chlorophyll content. The brightness (L*), red–green axis (a*), yellow–blue axis (b*), colour intensity (C), and tone (h°) values changed. The yield per hectare and nitrogen fertiliser partial productivity values were significantly increased. Overall, the T2 treatment resulted in the best outcome for the Yili area. In conclusion, partially substituting inorganic nitrogen with bio-organic fertiliser can effectively increase soil and leaf nutrient content and improve fruit yield and quality.

Effect of 1-MCP treatment on cellulase activity and its gene expression to improve postharvest quality of custard apple fruit

The custard apple fruit is a respiratory climacteric fruit. Cell wall polysaccharide metabolism causes it to soften and decay rapidly during postharvest storage, which lowers its quality and shortens its shelf life. The objective of this work was to investigate the effect of 24-hour treatment with 1-MCP (1.8 μL L−1) on the cellulase activity and its gene expression, evaluating the changes on postharvest quality of harvested custard apple fruit. The results showed that compared with the control group, 1-MCP treatment can depress the activity of cellulase and its gene expression level, by 11.37% and 25.25%, respectively. Furthermore, 1-MCP treatment could successfully preserve the firmness and prevent browning in appearance of the fruit, but had no discernible impact on the content of soluble solids (p < 0.05). Although the total amount of volatile compounds in treated custard apple fruits increased by 10 species compared with the control, 1-MCP treatment inhibited the production of esters and the degradation of aldehydes. After 1-MCP treatment, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) increased by 34.88%, 29.19%, and 16.97%, respectively. These results indicate that 1-MCP treatment is a potentially effective method to improve postharvest quality, and enhance storage efficiency of custard apple fruit.

Earthworm fermentation products enhance the apple replant soil environment and increase the yield and quality of apple fruit

The cultivation of apples in replanted orchards is essential given limitations in land resources. However, the presence of Fusarium and phenolic acids in the replanted soil harms the soil environment, which impedes the sustainable development of the apple industry. In this study, earthworm was used as the fermentation precursor protein to optimize the fermentation conditions, and the inhibition mechanism of the fermentation product on Fusarium and its potential to repair the apple replant soil environment were explored. Laboratory experiments showed that the optimum initial pH, temperature and time of earthworm fermentation were 7, 37 °C and 10 d, respectively. The inhibition rates of earthworm fermentation products against F. oxysporum, F. solani, F. proliferatum, and F. moniliforme were 79.8%, 75.1%, 78.7% and 79.2%, respectively. The inhibition rates of spore germination on F. oxysporum, F. solani, F. proliferatum, and F. moniliforme were 83.8%, 87.3%, 83.2% and 84.8%, respectively. In the field, use 300 mL of earthworm fermentation products for each planting pits before planting. The experimental results showed that, compared with the control, the content of soil pathogenic Fusarium and phenolic acid in Wantou (W3) were decreased by 75.1% and 59.8%, respectively, after treatment with earthworm fermentation products in 2019. Soil urease, phosphatase, sucrase and catalase activities increased by 383.2%, 78.2%, 130.3% and 43.5%, respectively. The fruit weight, anthocyanin content, soluble sugar, sugar-acid ratio, total ester ratio, total ester concentration and yield increased by 80.7%, 60.6%, 25.6%, 50.3%, 19.7%, 262.4% and 193.5%, respectively, while titratable acid content decreased by 16.9%. In conclusion, earthworm fermentation products can be used as a sustainable amendment to control apple replant disease.

Relationship of leaf nutrient concentrations on fruit yield and quality of apple

Relationship of leaf nutrient concentrations on fruit yield and quality of apple

COMPREHENSIVE ASSESSMENT OF THE QUALITY AND BIOLOGICAL VALUE OF APPLE FRUIT OF DIFFERENT VARIETIES GROWN IN THE CONDITIONS OF THE REPUBLIC OF ADYGEA

Background. Apple fruits are a valuable food product with a unique chemical composition that determines the taste and biological value. The chemical composition of fruits depends on the variety of apples, ripening terms, conditions and place of growth, which makes research relevant in the conditions of a certain region, including the Republic of Adygea, where horticulture not only has deep historical roots, but has been actively reviving and developing in recent decades. with the use of new technologies and the introduction of new varieties.&#x0D; Target. Carrying out a comprehensive assessment of the quality and biological value of apple fruits of different varieties grown in the conditions of the Republic of Adygea on the basis of a study of organoleptic, physicochemical and biochemical indicators.&#x0D; Materials and methods. The objects of the study were samples of apple fruits of the agricultural enterprise LLC “Yumiks” of 5 varieties: Braeburn, Granny Smith, Idared, Florina, Simirenko, grown in the conditions of the Republic of Adygea. In the samples under study, the determination of organoleptic, physicochemical and biochemical parameters was carried out: soluble solids (SS), titratable acids per malic acid, vitamin C, total sugars, iron, polyphenol oxidase activity, antioxidant activity (AOA). Statistical data processing was carried out in MS Excel 2016.&#x0D; Results. For the first time, on the basis of a complex of organoleptic, physicochemical and biochemical methods, studies of apple varieties grown in the Republic of Adygea were carried out: Florina, Idared, Granny Smith, Braeburn, Simirenko. It has been established that the highest index of sensory quality has apple varieties Braeburn and Simirenko, the Braeburn variety is distinguished by a high content of solids and sugars, more harmonious taste, i.e. the optimal ratio of sugar to acid is found in the Braeburn and Florina varieties. The highest content of vitamin C and bioavailable iron is characteristic of Braeburn and Simirenko apple varieties. Polyphenol oxidase activity in Simirenko, Idared and Florina varieties was higher than in samples of other varieties, while a higher AOA value was found in Granny Smith.&#x0D; Conclusion. The data obtained by us on the basis of a comprehensive study of apple varieties new to the Republic of Adygea, but already in a certain consumer demand, will allow us to give an objective assessment of their contribution to the biological value of the diets of various population groups, and also, subject to further monitoring studies, can be used gardeners of the Republic of Adygea when expanding the area under varieties with the highest taste and stable indicators of biological value.

Genomic analysis of fruit size and shape traits in apple: unveiling candidate genes through GWAS analysis.

Genomic tools facilitate the efficient selection of improved genetic materials within a breeding program. Here, we focus on two apple fruit quality traits: shape and size. We utilized data from 11 fruit morphology parameters gathered across three years of harvest from 355 genotypes of the apple REFPOP collection, which serves as a representative sample of the genetic variability present in European-cultivated apples. The data were then employed for genome-wide association studies (GWAS) using the FarmCPU and the BLINK models. The analysis identified 59 SNPs associated with fruit size and shape traits (35 with FarmCPU and 45 with BLINK) responsible for 71 QTNs. These QTNs were distributed across all chromosomes except for chromosomes 10 and 15. Thirty-four QTNs, identified by 27 SNPs, were related for size traits, and 37 QTNs, identified by 26 SNPs, were related to shape attributes. The definition of the haploblocks containing the most relevant SNPs served to propose candidate genes, among them the genes of the ovate family protein MdOFP17 and MdOFP4 that were in a 9.7kb haploblock on Chromosome 11. RNA-seq data revealed low or null expression of these genes in the oblong cultivar "Skovfoged" and higher expression in the flat "Grand'mere." The Gene Ontology enrichment analysis support a role of OFPs and hormones in shape regulation. In conclusion, this comprehensive GWAS analysis of the apple REFPOP collection has revealed promising genetic markers and candidate genes associated with apple fruit shape and size attributes, providing valuable insights that could enhance the efficiency of future breeding programs.

Unveiling the Hidden Potential: Exploring Floral Bud Types for Enhanced Fruit Quality in Apples

Unveiling the Hidden Potential: Exploring Floral Bud Types for Enhanced Fruit Quality in Apples

Optimization of apple fruit flavor by MdVHP1-2 via modulation of soluble sugar and organic acid accumulation

For fleshy fruits, the content and ratio of organic acids and soluble sugars are key factors for their flavor. Therefore, a better understanding of soluble sugar and organic acid accumulation in vacuoles is essential to the improvement of fruit quality. Vacuolar-type inorganic pyrophosphatase (V-PPase) has been found in various plants with crucial functions based on the hydrolysis of PPi. However, the effects of V-PPase on the soluble sugar and organic acid accumulation in apple fruit remain unclear. In this study, MdVHP1-2, a V-PPase protein in the vacuolar membrane, was identified. The results showed a positive correlation between the expression of MdVHP1-2 and the sugar/acid ratio during ripening of apple fruits. A series of transgenic analyses showed that overexpression of MdVHP1-2 significantly elevated the contents of soluble sugars and organic acids as well as the sugar/acid ratio in apple fruits and calli. Additionally, transient interference induced by MdVHP1-2 expression inhibited the accumulation of soluble sugars and organic acids in apple fruits. In summary, this study provides insight into the mechanisms by which MdVHP1-2 modulates fruit flavor through mediation of soluble sugar and organic acid accumulation, thereby facilitating improvement of the overall quality of apple and other fruits.

Chromosome-level phased genome assembly of "Antonovka" identified candidate apple scab-resistance genes highly homologous to HcrVf2 and HcrVf1 on linkage group 1.

Apple scab, a fungal disease caused by Venturia inaequalis, leads to losses in both yield and fruit quality of apples (Malus domestica Borkh.). Most commercial apple cultivars, including those containing the well-characterized Rvi6-scab-resistance locus on linkage group (LG) 1, are susceptible to scab. HcrVf2 and HcrVf1 are considered the main paralogs of the Rvi6 locus. The major apple scab-resistance loci Vhc1 in "Honeycrisp" and Rvi17 in "Antonovka," were identified in close proximity to HcrVf2. In this study, we used long-read sequencing and in silico gene sequence characterization to identify candidate resistance genes homologous to HcrVf2 and HcrVf1 in Honeycrisp and Antonovka. Previously published chromosome-scale phased assembly of Honeycrisp and a newly assembled phased genome of Antonovka 172670-B were used to identify HcrVf2 and HcrVf1 homologs spanning Vhc1 and Rvi17 loci. In combination with 8 available Malus assemblies, 43 and 46 DNA sequences highly homologous to HcrVf2 and HcrVf1, respectively, were identified on LG 1 and 6, with identity and coverage ranging between 87-95 and 81-95%, respectively. Among these homologs, 2 candidate genes in Antonovka and Honeycrisp haplome A are located in close physical proximity to the scab-resistance marker Ch-Vf1 on LG 1. They showed the highest identity and coverage (95%) of HcrVf2 and only minor changes in the protein motifs. They were identical by state between each other, but not with HcrVf2. This study offers novel genomic resources and insights into the Vhc1 and Rvi17 loci on LG 1 and identifies candidate genes for further resistance characterization.

Apple fruit quality characteristics during long-term storage as a function of cool-down regime

Apple fruit quality characteristics during long-term storage as a function of cool-down regime

Crop load management in high density apple plantation

Aim of study: To optimize the best thinning method and elucidate its effect on fruit size, quality, yield and return bloom in apple under high density plantation in sub-temperate zone of India. Area of study: Dr. Yashwant Singh Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh, India. Material and methods: The experiment consisted of 30 combinations of 10 thinning (chemical and manual) treatments (T1: 10 mg L-1 NAA; T2: 20 mg L-1 NAA; T3: 100 mg L-1 BA; T4: 200 mg L-1 BA; T5: 100 mg L-1 Metamitron; T6: 200 mg L-1 Metamitron; T7: crop load of 4 fruits cm-2 TCSA; T8: crop load of 6 fruits cm-2 TCSA; T9: crop load of 8 fruits cm-2 TCSA and T10: control - no thinning) and 3 cultivars treatments (‘Jeromine’, ‘Redlum Gala’ and ‘Super Chief’), replicated five times over three growing seasons (2020 to 2022). Main results: The highest return bloom, fruit size, red skin color (RSC), sugars content, and anthocyanin content were produced due to manual thinning while maintaining a crop load of 4-6 fruits cm-2 TCSA (trunk cross sectional area). ‘Jeromine’ cultivar produced fruits with better yields, productivity, and RSC. ‘Redlum Gala’ had fruits with a better extent of thinning, return bloom, and sugar content. The extent of thinning showed a significant positive correlation with return bloom, fruit quality and physicochemical parameters, and growth in apples under high-density plantations. Research highlights: A possible threshold for optimal fruit quality and consistent return bloom is around 4-6 fruits cm-2 TCSA in apple under high density plantation in India.

Impact of 24-epibrassinoliode and methyl jasmonate on quality of Red Delicious apples.

Changes in apple fruit quality indices in response to foliar spray with 24-epibrassinolide (EBL) at 0 and 1 μmol L-1 and methyl jasmonate (MeJA) at 0 and 0.5 μmol L-1 , as well as the combination of these phytohormones, were investigated at harvest and during cold storage. Both phytohormones synergistically enhanced the fruit firmness, specific weight, size, fresh weight, water content, total antioxidant activity, total phenolics, ascorbic acid, total anthocyanins, total soluble solids/titratable acidity ratio and precocity. In addition, the fruit abscission pattern was changed in response to different treatments. Treated fruit exhibited lower weight loss and internal breakdown symptoms and higher total soluble solids index, firmness and phytochemicals during cold storage. A negative correlation was seen between fruit mass, firmness, specific weight, antioxidant activity, total phenolics and vitamin C content with internal breakdown occurrence and weight loss. Foliar spray with EBL and MeJA during the growth season is a good environmental friendly and safe method for enhancing the apple fruit different quality parameters, marketability and postharvest life. © 2023 Society of Chemical Industry.

The Development of Apple MRI Dataset for Internal Quality Analysis

Internal quality assessment of agricultural products is challenging for exporting premium quality of Agri products like apple fruits. In this, we have analyzed the internal quality of apple fruits by a non-destructive method. We have developed our own dataset of MR images of apples by subjecting 21 apples into MRI scanning for the development of robotics detection of internal defects in apples. This MRI scanning led into 196 MR images Comparative study was carried out on the basis of MRI images with respective external photographic images of apple fruits. The apples were grouped into four categories depending on external and internal defects. By this study, we can easily identify the percentage and area of the defect without affecting the physical appearance of the apple.

Association of hydrothermal conditions one month before harvest and degree of maturity with the yield of sound apple fruit aft er storage

The quality and storability of apple fruits depend on the apple variety and degree of maturity, as well as weather conditions of the growing season. For each pomological variety, the picking maturity of the fruit is individual. It depends on geographical and climatic area of cultivation, weather conditions of a particular season – the hydrothermal conditions of the active growing season (the sum of active temperatures, precipitation and hydrothermal coefficient (HTC)). Fruits should be harvested at the optimal maturity stage to ensure maximum duration of storage and preservation of fruit quality. The paper presents a quantitative assessment of the impact of weather conditions one month before harvesting in different years (2014, 2016, 2018, 2019) on the yield of sound apple fruits of Priokskoye and Rozhdestvenskoe breeding varieties (the Russian Research Institute of Fruit Crop Breeding) after storage at +2 °С. A certain regularity was revealed in the yield of marketable fruits after storage, depending on hydrothermal conditions, 30 days before harvesting. Regression equations for Priokskoye and Rozhdestvenskoye varieties grown in central Russia were obtained on the basis of HTC indicators and the joint effect of the sum of active temperatures ≥ 10°C and HTC. The equations can be used to predict the yield of sound fruits after storage, by interpolating and extrapolating empirically obtained data.

Influence of hot water treatment on nutritional quality attributes of cold stored apple (Malus × domestica)

The present study was carried out at ICAR-Indian Agricultural Research Institute, New Delhi during 2021–2023 to study the effect of postharvest hot water treatment (HWT) on the nutritional quality attributes of apple [Malus × domestica Borkh.] cv. Royal Delicious. Apple fruits were exposed to hot water at 48, 50, 52 and 54°C for 2, 3, 4 and 5 min. Following the treatment, the fruits were cold stored (2±1°C, 90–95% relative humidity) for 90 days and evaluated for quality changes at every 15 days interval. Our results revealed that HWT of apple fruits at 48°C and 50°C were best for optimum retention of nutritional quality of apple fruits. Exposure of fruits to HWT at 48°C/5 min and 50°C/2 min resulted in least (0.73%, 0.75%) loss of ascorbic acid and anthocyanin content (0.10%, 0.21%), respectively as compared to other temperature-time combinations. At the end of a three month storage period, under control treatment, fruits exhibited 9.56% reduction of antioxidant (AOX) activity in comparison to 0.17–2.21% reduction in HWT apples. The maximum loss in quality attributes was noticed at highest temperature-time exposure (54°C/5 min). Thus, it was observed that the right combination of temperature and time for HWT is crucial to maintain fruit quality attributes without compromising nutritional value.

Soil acidifying treatments do not improve ‘Honeycrisp’ apple fruit quality

Soil acidifying treatments do not improve ‘Honeycrisp’ apple fruit quality

Application of living mulch in rows of the apple trees on several rootstocks – long-term evaluation

The long-term influence of several living mulches on apple tree growth, nutrient status, yield, and fruit quality concerning the year of cover crop sowing in tree rows was evaluated in the Lower Silesia region in the southwestern part of Poland. The estimation was conducted in six apple tree ‘Ligol’ populations differentiated by the rootstock: M.26, M.9, P 60, P 2, P 16, and P 22. In experiment no. 1, one-year-old nursery stock was planted, and perennial living mulches were sown: colonial bent grass (Agrostis vulgaris With.) and white clover (Trifolium repens L.) in the same year and blue fescue (Festuca ovina L.) in the following year. In experiment no. 2, which involved two-year-old stock, the sowing of blue fescue was delayed until the second, third, fourth, and fifth years following orchard planting. The presence of the cover crop significantly affected young tree growth when one-year-old trees were planted. The sowing of the living mulch in the first or the second year after tree planting led to a significant reduction in the cumulative yield obtained from the young trees. The living mulch improved the red coloration of the fruit skin in the young orchard, but it caused a reduction in the mean fruit weight and size. However, it also contributed to decreased nitrogen concentration in the leaves of the apple trees, and the tree tolerance to living mulch increased as the orchard aged. A choice of semidwarf rootstock, postponed sowing of cover crop, and high-quality nursery stock were recognized as the most important factors for fostering apple tree tolerance to living mulches in tree rows.