Apple Fruit Quality Research Articles

‘루비에스’ 사과의 저온저장 중 과실품질 유지를 위한 1-methylcyclopropene 처리 효과

This study was conducted to evaluate the effect of different 1-methylcyclopropene (1-MCP) concentrations on fruit quality of small-sized RubyS apples during cold storage. After harvesting, the fruits were treated with 1-MCP at 0.5 or 1 μL/L concentrations and, subsequently, stored at 0°C for 6 months. After 6 months, the flesh firmness of untreated fruits, which was 85.4 N at harvest, had gradually decreased to 46.5 N; however, that of 1-MCP-treated fruits was maintained at 59.1 and 59.5 N. Titratable acidity (TA) of untreated fruits had also decreased from 0.42 to 0.24%, whereas that of 1-MCP-treated fruits was maintained at 0.26 and 0.27%. Soluble solids content (SSC) did not differ in all fruits. However, the 1-MCP-treated fruits had lower levels of SSC/TA ratio than untreated fruits. Moreover, after 6 months, the ethylene production had increased to 47.0 μL/kg/h in the untreated fruits, whereas 1-MCP blocked the ethylene production at 1.4 and 1.7 μL/kg/h. The weight loss and peel color variables remained unaffected by 1-MCP treatments. Thus, these results indicated that, for RubyS apples, the storability was only 2 months at 0°C without treatment, which can be extended to 6 months with 1-MCP treatments. The application of 1-MCP at 0.5 μL/L concentration is effectively and economically sufficient to maintain the quality of RubyS apples.

Geopedological transects in karst landscapes in Campeche, Mexico

Objective: Apples cultivated in Mexico generally are smaller and softer than those produced in other geographical latitudes considered as optimal for apple production. The aim of this evaluation was determine the effect of applications with calcium, nitrogen, potassium, magnesium, sulfur and naphthaleneacetic acid (NAA), as well as the harvest date on the quality of apple fruits. Methodology ‘Golden Smoothie’ apple trees were treated foliarly with CaCl2 with and without NAA, and with a mixture of N, K, Mg and S or gypsum applied to soil for two years. Apples were harvested at 141 (regular harvest date), 161 (mid-late harvest) and 171 days (late harvest) after full bloom (DAFB) and evaluated for quality at harvest time and during their storage at 0°C for up to 179 days. Results: Foliar applications of CaCl2 significantly increased the calcium content in fruit and leaves, but fruit quality, including firmness, was not influenced. Fertilization of soil with the mixture of nutrients, including CaSO4, did not influence the fruit quality. Lately harvested fruit was 14.9% heavier but 17.1% softer than fruit picked at the commercial harvest date. Delaying of fruit harvest reduced about 43 d the storability of fruit. Based in these results, the relative softness of apples grown in Mexico is not related with its calcium content, hence unlikely to be overcome with the application of this mineral. Conclusions: Even in the control fruits, both seasons, the stored fruits do not show some physiological disorder as bitter pit

Effect of the harvest date, calcium and other chemicals on the quality and storability of ‘Golden Smoothie’ apples

Apples cultivated in Mexico generally are smaller and softer than those produced in other geographical latitudes considered as optimal for apple production. The aim of this evaluation was determine the effect of applications with calcium, nitrogen, potassium, magnesium, sulfur and naphthaleneacetic acid (NAA), as well as the harvest date on the quality of apple fruits. ‘Golden Smoothie’ apple trees were treated foliarly with CaCl2 with and without NAA, and with a mixture of N, K, Mg and S or gypsum applied to soil for two years. Apples were harvested at 141 (regular harvest date), 161 (mid-late harvest) and 171 days (late harvest) after full bloom (DAFB) and evaluated for quality at harvest time and during their storage at 0°C for up to 179 days. Foliar applications of CaCl2 significantly increased the calcium content in fruit and leaves, but fruit quality, including firmness, was not influenced. Fertilization of soil with the mixture of nutrients, including CaSO4, did not influence the fruit quality. Lately harvested fruit was 14.9% heavier but 17.1% softer than fruit picked at the commercial harvest date. Delaying of fruit harvest reduced about 43 d the storability of fruit. Based in these results, the relative softness of apples grown in Mexico is not related with its calcium content, hence unlikely to be overcome with the application of this mineral. Even in the control fruits, both seasons, the stored fruits do not show some physiological disorder as bitter pit.

Prediction of Apple Fruit Quality by Soil Nutrient Content and Artificial Neural Network

The effect of soil nutrient content on fruit yield and fruit quality is very important. To explore the effect of soil nutrients on apple quality we investigated 200 fruit samples from 40 orchards in Feng County, Jiangsu Province. Soil mineral elements and fruit quality were measured. The effect of soil nutrient content on fruit quality was analyzed by artificial neural network (ANN) model. The results showed that the prediction accuracy was highest (R2 = 0.851, 0.847, 0.885, 0.678 and 0.746) in mass per fruit (MPF), hardness (HB), soluble solids concentrations (SSC), titratable acid concentration (TA) and solid-acid ratio (SSC/TA), respectively. The sensitivity analysis of the prediction model showed that soil available P, K, Ca and Mg contents had the greatest impact on the quality of apple fruit. Response surface method (RSM) was performed to determine the optimum range of the available P, K, Ca, and Mg contents in orchards In Feng County, which were 10∼20 mg⋅kg−1, 170∼200 mg⋅kg−1, 1000∼1500 mg⋅kg−1, and 80∼200 mg⋅kg−1, respectively. The research also concluded that improving the content of available P and available Ca in orchard soil was crucial to improve apple fruit quality in Feng County, Jiangsu Province.

POLLEN QUALITY AND SELECTION OF POLLINATORS OF CULTIVARS OF COLUMNAR TYPE APPLE

The apple tree (Malus domestica Borkh.) is a flowering tree whose productivity depends on successful cross-pollination. The efficiency of the pollination process significantly affects the quantity and quality of apple fruits. In addition to the basic requirements for fruit set and tree productivity, the presence of different pollen sources (different cultivars of the orchard) has a positive effect on fruit quality parameters. It is possible to make a profit from an apple orchard several years after planting, so the choice of cultivar is very important, because the economic feasibility of growing plants depends on it. The purpose of this study was to determine the viability of pollen of columnar apple cultivars and the selection of pollinator cultivar. The research was carried out during 2019–2022 at the V. L. Symyrenko Department of Horticulture of the National University of Life and Environmental Sciences of Ukraine. According to the results of the research, it was established that in the conditions of the Western Forest Steppe of Ukraine, the investigated columnar varieties form pollen of medium viability, pollen tubes reach a medium length, insufficient cross-fertility is observed, and the best pollinators for them are universal pollinators, Golden Gem’ and Professor Springer’ cultivars. In general, columnar fruit set is good from free pollination. Several conditions are necessary for satisfactory cross-pollination, namely: flowering of the pollinator cultivar must be simultaneous with the main cultivar; the pollinator cultivar must have pollen of high viability; the location of the pollinator cultivar should be near the fruit-bearing tree; the garden requires the presence of bees and other insects during flowering.

Watercore and fruit quality of apple cultivars as influenced by harvesting time and calcium sprays

Watercore and fruit quality of apple cultivars as influenced by harvesting time and calcium sprays

Study of the effect of storage periods and temperatures on the quality of apple fruits, cultivar Golden Delicious

This study aims to know the extent to which the fruits of the “Golden Delicious” apple variety grown in Al-Wardiya farms can retain their quality during cold storage, by studying the change in some natural characteristics of the fruits that were stored in special refrigerators during the 2019 and 2020 planting seasons, and the treatments were storage for (0, 60, 120) days at a temperature of (0, 3 oC) and the results obtained showed that the longer the storage period, the lower the quality of the fruits The degree of coloration of the fruits, their starch content and their hardness decreased, and their weight loss increased with the progression of the storage period, Also, the fruits retained their quality when stored at zero degrees Celsius better than those stored at 3 degrees Celsius.

Impact of the B-Plus white pearl (Belyi Zhemchug) preparation on the spring frost tolerance, yield and quality of apple crops

In 2021–2022, experiments were conducted at the Laboratory of Fruit Crop Resistance Physiology, All-Russia Institute for Fruit Crops Breeding (VNIISPK), to investigate the action of the “White Pearl Antifreeze” (Belyi Zhemchug Antifriz) phytomodulator and the “White Pearl Drip Ca + Mg” (Belyi Zhemchug Drip Ca+Mg) phytocorrector produced by the AgroPlus Group of Companies, LLC. Experimental and control plots were characterized by dark-gray forest soils with a humus content of 3-4 % and a humus horizon thickness of 30–35 cm. Apple trees cv. Sinap Orlovsky (VNIISPK) grafted on semi-dwarf rootstock 54-118 were planted in 2013 according to a 6 x 3 m scheme. Natural grassing was used in row spacings; herbicides were applied around the seedlings. The experimental design included: 1) control (water treatment) and 2) foliar treatment with a 1 % solution of “White Pearl Antifreeze” + a 1 % solution of “White Pearl Drip Ca+Mg”. The experiment was conducted in three replications with five observed trees in each. Our aim was to assess the effect of the mentioned preparations on the spring frost tolerance, yield, and quality of apple fruit under the weather conditions of 2021. Foliar treatments with the studied preparations reduced the frost damage to Sinap Orlovsky apple buds by 6.3 % at -3.5 °С and by 10.4 % at -4 °С. The conducted summer foliar treatments with the organomineral mixture under study intensified the growth and ripening of apple fruit. The improved protein-carbohydrate metabolism, water regime, photosynthetic activity, and donor-acceptor leaf–fruit relations increased the fruit weight by 10 g and the yield by 1.8 times. The conclusion is made that the B-PLUS “White Pearl Antifreeze” preparation exhibits a complex effect in terms of increasing plant tolerance to low-temperature spring damage, thus improving the yield and quality of apple crops.

Transcriptional Effects of Rootstock on Scion after Drought: A Case Study of Using MdGH3 RNAi as the Rootstock

Drought stress is an important environmental factor limiting apple yield and fruit quality. Previously, we identified GRETCHEN HAGEN3.6 (GH3.6) as a negative regulator of drought stress in apple trees. Using transgenic MdGH3 RNAi (knocking down MdGH3.6 and its five homologs) plants as rootstock can increase drought tolerance, water use efficiency, flowering, and fruit quality of the Fuji scion after drought stress. However, the molecular mechanism behind this phenomenon is still unknown. Here, we performed transcriptome sequencing of the grafted plants (Fuji/GL-3 where Fuji was used as the scion and non-transgenic GL-3 was used as the rootstock, and Fuji/MdGH3 RNAi where MdGH3 RNAi was used as the rootstock) under control and drought conditions. Under control conditions, 667 up-regulated genes and 176 down-regulated genes were identified in the scion of Fuji/MdGH3 RNAi, as compared to the scion of Fuji/GL-3. Moreover, 941 up-regulated genes and 2226 down-regulated genes were identified in the rootstock of MdGH3 RNAi plants relative to GL-3. GO terms of these differentially expressed genes (DEGs) in scion and rootstock showed associations with plant growth, fruit development, and stress responses. After drought stress, 220 up-regulated and 452 down-regulated genes were identified in MdGH3 RNAi rootstock, as compared to GL-3. Significantly enriched GO terms included response to abiotic stimulus, cell division, microtubule-based process, metabolic and biosynthetic process of flavonoid, pigment, and lignin. The comparison between the scion of Fuji/MdGH3 RNAi and Fuji/GL-3 yielded a smaller number of DEGs; however, all of them were significantly enriched in stress-related GO terms. Furthermore, 365 and 300 mRNAs could potentially move from MdGH3 RNAi rootstock to scion under control and drought conditions, respectively, including FIDDLEHEAD (FDH), RESPONSIVE TO DESICCATION 26 (RD26), ARS-binding factor 2 (ABF2), WRKY75, and ferritin (FER). Overall, our work demonstrates the effects of rootstock on scion at the transcriptional level after drought stress and provides theoretical support for further understanding and utilization of MdGH3 RNAi plants.

Application of γ-aminobutyric acid (GABA) improves fruit quality and rootstock drought tolerance in apple

GABA (γ-aminobutyric acid) plays a multifaceted role in plant growth, fruit quality, and tolerance to abiotic stresses. However, its physiological roles and mechanisms in the fruit quality and response to long-term drought stress in apple remain unelucidated. To investigate the effect of GABA on apple fruit quality and drought tolerance, we sprayed exogenous GABA on apple cultivar “Cripps Pink” and irrigated rootstock M.9-T337 with GABA, respectively. Results showed that exogenous GABA could effectively improve the fruit quality of “Cripps Pink”, including increased sugar-to-acid ratio, flesh firmness, pericarp malleability, and GABA content, as well as reduced fruit acidity. In addition, pretreatment of M.9-T337 plants with GABA improved their tolerance to both long- and short-term drought stress. Specifically, 1 mM exogenous GABA increased the net photosynthetic rate, relative leaf water content, root-to-shoot ratio, and water use efficiency under long-term drought stress, and delayed the increased of the relative electrolyte leakage under short-term drought stress. RNA-seq analysis identified 1271 differentially expressed genes (DEGs) between nontreated and GABA-pretreated plants under short-term drought stress. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of these DEGs revealed that GABA may enhance plant drought resistance by upregulating the expression of genes related to “Biosynthesis of secondary metabolites”, “MAPK signaling pathway”, “Glutathione metabolism”, and “Carbon fixation in photosynthetic organisms”. In conclusion, these results revealed that exogenous GABA can improve fruit quality and enhance drought tolerance in apple.

Pruning effects on growth, yield and fruit quality of apple (Malus × domestica Borkh.) cv. Gale Gala

Pruning effects on growth, yield and fruit quality of apple (Malus × domestica Borkh.) cv. Gale Gala

Effect of Some Nano Fertilizers on Yield and Fruit Quality of Apple

Effect of Some Nano Fertilizers on Yield and Fruit Quality of Apple

Optimization of irrigation and nitrogen levels for a trade-off: Yield, quality, water use efficiency and environment effect in a drip-fertigated apple orchard based on TOPSIS method

Inappropriate water and nitrogen management has restricted apple production in the Loess Plateau of China. A 2-yr field experiment was conducted to investigate the effects of irrigation and nitrogen levels on apple yield, fruit quality, water and nitrogen use efficiency and soil nitrate-N residues under drip fertigation. Irrigation had two levels of upper irrigation limit, 85% (W1) and 100% (W2) of field capacity, and nitrogen rates included 0 (N1), 120 (N2), 240 (N3) and 360 (N4) kg ha−1. The results showed W1 significantly increased WUE in two years. Irrigation levels has not influenced yield attributes and fruit quality in 2020. In 2021, W1 increased fruit vitamin C, total soluble sugar and sugar-acid ratio by 10.02%∼46.54% with a slight yield reduction, and reduced nitrate-N leaching. Nitrogen rates over N3 reduced yield, WUE and fruit quality. Multi-objective evaluation revealed that W1N3 was the optimum irrigation and nitrogen rates for drip-fertigated apple production.

Efficient Identification of Apple Leaf Diseases in the Wild Using Convolutional Neural Networks

Efficient identification of apple leaf diseases (ALDs) can reduce the use of pesticides and increase the quality of apple fruit, which is of significance to smart agriculture. However, existing research into identifying ALDs lacks models/methods that satisfy efficient identification in the wild environment, hindering the application of smart agriculture in the apple industry. Therefore, this paper explores an ACCURATE, LIGHTWEIGHT, and ROBUST convolutional neural network (CNN) called EfficientNet-MG, improving the conventional EfficientNet network by the multistage feature fusion (MSFF) method and gaussian error linear unit (GELU) activation function. The shallow and deep convolutional layers usually contain detailed and semantic information, respectively, but conventional EfficientNets do not fully utilize the different stage convolutional layers. Thus, MSFF was adopted to improve the semantic representation capacity of the last layer of features, and GELU was used to adapt to complicated tasks. Further, a comprehensive ALD dataset called AppleLeaf9 was constructed for the wild environment. The experimental results show that EfficientNet-MG achieves a higher accuracy (99.11%) and fewer parameters (8.42 M) than the five classical CNN models, thus proving that EfficientNet-MG achieves more competitive results on ALD identification.

Supplementation of natural light duration promotes accumulation of sugar and anthocyanins in apple (Malus domestica Borkh.) fruit

Light is an environmental factor that is indispensable for plant growth and development. For fruit crops, prolonged light duration promotes fruit coloration and generally increases sugar accumulation, which improve the fruit appearance and flavor quality. Apple (Malus × domestica Borkh.) is a photophilic species for which the yield, fruit appearance, and flavor quality are strongly associated with the light environment. However, few studies have investigated the effect of modifying the light duration in a field environment on apple fruit quality. In this study, we used LED lighting to extend the light duration in an apple orchard after sunset and examined the effect on fruit quality. Strikingly, extending the light duration significantly promoted anthocyanins synthesis in the fruit skin and accumulation of soluble sugars in the fruit flesh. Based on RNA-sequencing results, we screened the MdWRKY40 transcription factor that regulates anthocyanins transport in the skin, and the MdMYB108 transcription factor that regulates sugar accumulation in the flesh. Functional analyses showed that MdWRKY40 could bind to the promoter of MdGSTF12 to promote the transport and accumulation of anthocyanins in the fruit skin. MdMYB108 couldbind to the promoter of MdPFK to promote the accumulation of soluble sugar in the fruit flesh. These findings provide valuable insight into the effect of regulation of the light environment on apple fruit quality, and will be crucial for determining the foremost apple-producing areas and the optimal growth environment.

Effect of Different Ratios of Cow Manure and Chemical Fertilizers on Fruit Quality of Gala Apples

Nutrient patterns can significantly influence the growth and development of fruit trees, especially fruit quality. In order to clarify the appropriate ratio of inorganic and organic fertilizers, six treatments with different ratios of cow manure and chemical fertilizers were set up in this study to evaluate the effects of different treatments on fruit yield, appearance quality, intrinsic quality and volatile substances. The results showed that, after replacing some chemical fertilizers with cow manure, the content of sugar, titratable acid, organic acid and aroma substance in the fruit increased, the fruit yield and colour did not change significantly, and the fruit weight per fruit decreased. Among the treatments of cow manure with chemical fertilizer, the fruits of 50% chemical fertilizer with 50% cow manure treatment had higher titratable acid (0.4%), malic acid (4.15 mg/g), sorbitol (0.51%), glucose (1.30%), fructose (5.81%) content and total aroma substance content (1047.82 μg/g) than chemical fertilizer alone. Compared to the fertilizer treatment alone, the application of cow manure instead of 50% of the chemical fertilizer had a positive effect on fruit quality.

MdZAT5 regulates drought tolerance via mediating accumulation of drought-responsive miRNAs and mRNAs in apple.

Drought limits apple yield and fruit quality. However, the molecular mechanism of apple in response to drought is not well known. Here, we report a Cys2/His2 (C2H2)-type zinc-finger protein, MdZAT5, that positively regulates apple drought tolerance by regulating drought-responsive RNAs and microRNAs (miRNAs). DNA affinity purification and sequencing and yeast-one hybrid analysis identified the binding motifs of MdZAT5, T/ACACT/AC/A/G. Chromatin immunoprecipitation quantitative polymerase chain reaction (ChIP-qPCR) and electrophoretic mobility shift assays (EMSAs) showed that MdZAT5 directly binds to the promoters of the drought-responsive genes including MdRHA2a, MdLEA14, MdTPX1, and MdCAT3, and activates their expression under drought stress. MdZAT5 interacts with and directly targets HYPONASTIC LEAVES1 (MdHYL1). MdZAT5 may facilitate the interaction of MdHYL1 with pri-miRNAs or MdDCL1 by activating MdHYL1 expression, thereby regulating the biogenesis of drought-responsive miRNAs. Genetic dissection showed that MdHYL1 is essential for MdZAT5-mediated drought tolerance and miRNA biogenesis. In addition, ChIP-qPCR and EMSA revealed that MdZAT5 binds directly to the promoters of some MIR genes including Mdm-miR171i and Mdm-miR172c, and modulates their transcription. Taken together, our findings improve our understanding of the molecular mechanisms of drought response in apple and provide a candidate gene for the breeding of drought-tolerant cultivars.

Greater Sunlight Exposure during Early Fruit Development Increases Polyphenol Concentration, Soluble Solid Concentration, and Fruit Mass of Cider Apples

The environmental factors that influence cider apple fruit quality, particularly bitter and astringent polyphenols, are not well understood. Five experiments were conducted to investigate how sunlight affects fruit and juice quality. In three studies, shade cloth was placed over entire trees or individual branches at different phenological stages, durations, and opacities. Influence of canopy microclimate was investigated by harvesting fruit from different sections of the tree canopy. In a final study, opaque paper bags were placed over fruit three weeks after full bloom (WAFB) until harvest. Polyphenol concentrations increased rapidly during the first five WAFB and were diluted as fruit grew larger. At harvest, fruit from unshaded trees had 32% greater total polyphenol concentrations and were 11% larger than trees shaded 1–5 WAFB. Shading branches later in the growing season reduced yield but had a modest and inconsistent reduction on polyphenol concentrations. Juice from fruit harvested from the top of the tree canopy had 33% greater polyphenol concentrations and 14% greater soluble solid concentrations than juice from the interior of the canopy. Bagging fruit had inconsistent impacts on polyphenol concentrations. We hypothesize that there is a source sink relationship between carbohydrate availability and polyphenol synthesis in apple fruit during the early stages of fruit development when most polyphenols are produced. Additionally, greater carbohydrate availability in canopies with greater sunlight exposure resulted in larger fruit and improved juice quality from a cider making perspective.

Integrative metabolomics and transcriptomics analyses reveal pivotal regulatory mechanisms of 1-methylcyclopropene in maintaining postharvest storage quality of ‘Fuji’ apples

Abstract In this study, integrative metabolomics and transcriptomics analyses were conducted to investigate the effects of 1-methylcyclopropene (1-MCP) on apple fruit quality during long-term cold storage. The results showed that 1-MCP (1 μL/L) treatment could maintain fruits apparent quality (i.e. external color and firmness), inhibit the increase of rot rate and soluble solids content/titratable acidity ratio, decrease ethylene release, and respiratory intensity during cold storage, and extend shelf life. Moreover, 1-MCP had long-term effects on the accumulation of many qualities related to metabolite and gene expression in fruits. 1-MCP affected genes related to metabolism at the early stage of storage, specifically those of the glycolysis and tricarboxylic acid cycle pathways. Genes related to the degradation of sucrose, starch, and cellulose were inhibited, and some starch and cellulose synthesis genes were up-regulated by 1-MCP. Apart from ethylene synthesis and signal transduction being inhibited by 1-MCP, several enzymes (pectinesterase, pectate lyase, polygalacturonase) were involved in pectin degradation, and degradation products of the cell wall (i.e. d-galacturonic acid and d-glucuronic acid) were also strongly inhibited, further maintaining fruit firmness. Cysteine, as precursor glutathione (GSH) related to plant resistance, up-regulated the synthase gene. However, the expression of genes related to cyanoalanine synthase and amino acid utilization pathways was suppressed by 1-MCP. Collectively, 1-MCP could maintain the postharvest quality of apple fruits.

Effects of Spraying Calcium Fertilizer on Photosynthesis, Mineral Content, Sugar–Acid Metabolism and Fruit Quality of Fuji Apples

This study was conducted at the Taidong Base of the Shandong Institute of Pomology, Tai’an City, Shandong Province, China, from May to October 2020. The effects of spraying calcium fertilizer on the photosynthetic characteristics, mineral element content, sugar and acid metabolism, and quality of apples were assessed. Fuji Apple Tianhong.2/SH/Malus robusta (M. robusta) was treated with the calcium fertilizers Niucui (Ca ≥ 100 g/L, B: 1–10 g/L) and Naipu 9 (Ca: 90 g/L, Mg: 21 g/L, N: 110 g/L) at the young fruit stage (25 May), the expansion stage (5 July), and the coloring stage (25 September). Water was sprayed as the control application. The results revealed that spraying calcium fertilizer increased the chloroplast pigment content and photosynthetic capacity of the apple leaves. Compared with the control, the net photosynthetic rate of apple leaves sprayed with Niucui increased by 4.3–34.6%, and that of leaves sprayed with Naipu 9 increased by 15.0–57.4%. Spraying calcium fertilizer promoted the accumulation of Ca, Mg, and B mineral elements in leaves and fruits while inhibiting the accumulation of Cu. Spraying calcium fertilizer improved the quality of apple fruit. Compared to the control fruit, the single fruit weight, fruit hardness, soluble solid content, and Vitamin C content of fruit sprayed with Niucui and Naipu 9 increased by 6.5 and 12.1%, 3.6 and 16.1%, 6.3 and 12.0%, and 30.5 and 29.4%, respectively. Spraying calcium fertilizer increased the sugar content and decreased the acid content of the apples. Naipu 9 was more effective at increasing fruit sugar content, especially sucrose and sorbitol, while Niucui was more effective at reducing the acid content, especially malic acid. This was observed because Naipu 9 increased the sugar metabolism enzyme activity, while Niucui increased the acid decomposition-related enzyme activity. In conclusion, according to the nutrition quality and flavor of the fruit, Naipu 9 application was determined to be the best fertilizer for the Fuji apple.