Fruit Sugar Content Research Articles

Date-Palm Compost as Soilless Substrate Improves Plant Growth, Photosynthesis, Yield and Phytochemical Quality of Greenhouse Melon (Cucumis melo L.)

The selection of adequate substrate for soilless culture is based on technical and economic considerations. Therefore, the search for alternatives by the valorization of natural by-products is gaining importance. The main objective of this study was to compare the effects of local farm resources, date-palm waste, as culture substrate, to coconut fiber (CF) (commonly used in soilless culture) on melon (Cucumis melo L.) plant growth, water relations, photosynthesis, chlorophyll fluorescence as well as phytochemical analysis under hydroponics culture system. Two growing substrates were tested: the compost of date palm waste added to animal manure (7:3 w w−1) (DPAM) and the date palm trunk compost (DPT). Coconut fiber and soil were used as positive and negative controls, respectively, in randomized blocks. Results showed that the vegetative growth was improved under DPT and CF substrates while CF substrate enhanced fruit yield and phytochemical properties: Total soluble solids TSS (% Brix), total dissolved solutes (TDS); Titratable acidity (as citric acid); Sugar content and juice pH of melon fruit. Date-palm waste-based substrates enhanced the vegetative growth and the fruit yield of melon as compared to soil-based culture. It seems that date palm waste-based substrates, especially trunk compost, could be promising and cheaper alternatives compared to coconut fiber substrates commonly used in Tunisia in soilless cultures.

High Density Planting In Litchi Cv. Bombai For Plant Vigour, Fruit Yield And Quality Under New Alluvial Zone Of West Bengal

A field experiment was carried out at Horticultural Research Station, Mondouri, BCKV, West Bengal during the year 2014 to 2017 to study the effect of different planting system cum high density planting in litchi cv. Bombai for plant physico-chemical properties under new alluvial zone of West Bengal. The experiment was laid out in RBD consisting of five treatments viz. Square system, Cluster planting, Paired row, Single hedge row and Double hedge row system with four replications on 12 years old healthy plants. Different planting system cum high density planting significantly influenced the plant characters of litchi. Among the physical characters, maximum plant height (5.95 m) was recorded from double hedge row planting followed by single hedge row while the spread of plant and trunk girth was found maximum in square system. Chlorophyll content of leaf (10.43 mg g-1), number of fruit set per panicle and fruit retention per panicle was found maximum in square system of planting. The maximum yield (12.87 t/ha) was recorded in double hedge row system of planting while the minimum (9.01 t/ha) from square system. The total soluble solids (17.08 0brix), total sugar content, ascorbic acid and anthocyanin content (35.51 mg/100g) of fruits was found maximum in square system of planting while the minimum in double hedge row system. Finally, it can be concluded that double hedge row planting system was effective in obtaining maximum yield per hectare, while square system of planting was effective in improving the physico-chemical properties of fruits.

Analysis of physicochemical attributes, contamination level of trace metals and assessment of health risk in mango fruits from Southern region Ethiopia

Heavy metal pollution has become one of the most threats that can endanger human health due to accumulation and consumption of fruits. Our study was aimed to evaluate physicochemical quality parameters, level of heavy metals, and assessment of health risks of lead (Pb), Manganes (Mn), zinc (Zn), iron (Fe), copper (Cu), chromium (Cr), and cadmium (Cd) in mango fruits from Arba Minch, Wolaita Sodo, and Damote Gale study areas. Quality parameters such as, total soluble solid, moisture, ash, titratable acidity, pH, total sugar, reducing sugar and non-reducing sugar, fat and fiber content of mango fruit were ranged between 15.68° and 18.92°B, 81.080-84.320 %,g, 4.040-4.080, 11.56-12.95%, 10.07-12.54%, 1.60-3.83%,0.397-0.673%, and 1.338-2.375% 0.283-1.030 %, 0.311-0.366mg/100g, 4.040-4.080, 11.56-12.95 %, 10.07-12.54 %, 1.60-3.83 %,0.397-0.673 %, and 1.338-2.375 % respectively. The average levels of metals in mango fruits were in the range Fe (1.166-1.486mg/kg), Cu (0.019-0.198mg/kg), Mn (0.121-0.239mg/kg), Zn (0.134-0.321mg/k), Pb (0.035-0.097mg /kg) and Cd (0.193mg/kg). Chromium is not detected in our study, because its level is below the detection limit. On average within metals, the highest level was obtained in Fe in the range 1.166-1.486mg/kg, whereas the minimum level was determined in Pb from 0.035 to 0.097mg/kg. The EDI values of accumulated elements in mango fruits follows the increasing order as; Fe Zn > Mn > Cu > Cd > Pb. Except Damot Gale sample in moderate range, the values of total carcinogenic risks (TCR) in all metals were less than 1 × 10-6, which is considered to be safe. All THQ and HI values were 1, which indicates that the accumulated metals did not contribute risk for human health. The present study clearly indicated that the consumption of mango fruits in the studied areas does not pose any health hazard associated with any of the selected heavy metals.

Study on the production of various dried products from apricot varieties

This article is devoted to obtaining various methods of drying a zoned apricot cultivar in Uzbekistan. Before laying for drying, the sugar content of fresh fruits was 17-21.5%. The output of dried products was 15.3-19%, a relatively high yield is allocated when dried for dried apricots, kaisa (19-22%). A relatively good organoleptic assessment (4.4-4.5points) distinguishes the varieties from the apricot Yubileiny Navoi, Gulyungilyuchak, when dried for dried apricots.

Physicochemical substances and bioactive components of wild cornelian cherry (Cornus mas L.) fruits in Erzincan province of Eastern Turkey

Turkey has a very rich flora due to diverse climatic and topographic conditions within the country. Cornelian cherry (Cornus mas L.) is an important wild edible fruits and widely distributed in Turkey and well known for its fruit antioxidants and nutrients. In this study, phytochemical content in fruits of a number of Cornelian cherry genotypes in Erzincan region were determined. The biochemical analysis included organic acids, sugars, vitamin C, antioxidant and individual phenolic compounds. In the study, organic acid content was between 253.09 mg/100 g and 112.50 mg/100 g. Vitamin C content varied between 115.85 mg/100g and 43.77 mg/100 g. Likewise, the sugar content of Cornelian cherry fruits varied from 6.17 g/100 g to 4.06 g/100 g. When the antioxidant content was examined, the highest antioxidant was 980.91 ?mol TE/g fresh weight (FW) base and the lowest was 490.38 ?mol TE/g FW. In the genotypes examined, gallic acid was determined as the highest among the individual phenolic compounds, while the individual phenolic amounts ranged from 38.93 mg/100 g FW to 4.31 mg/100 g FW. As a result of the study, it was determined that Cornelian cherry fruits are very rich in vitamin C and other phytochemicals and as a result of this examination, 24ER04 and 24ER08 genotypes came to the fore.

Promising varieties of sour cherry Prunus cerasus L. with a complex of fruit quality traits for growing in the southern Russia

Southern assortment of cherries does not quite meet the modern requirements of production. Many varieties are low-productive, not resistant to cherry leaf spot ( Coccomyces hiemalis ) and moniliosis ( Monilia cinerea ), small-fruited, with low taste qualities. However, new varieties have been created that have not been studied by the complex of consumer and commodity qualities of fruits. Thus, evaluation of new varieties for these traits is relevant. The aim of the research was to evaluate cherry varieties of different origin for commodity, biochemical, and consumer qualities of fruits. The research was carried out in the Kuban horticultural zone of the Krasnodar territory. Objects of the research were 9 varieties of sour cherry trees. Field and laboratory studies were conducted according to Program and methodology of varietal study of fruit, berry and nut crops (1999), Methodological instructions on chemical and technological variety testing of vegetable, fruit and berry crops for canning industry (1993). Statistical analysis was carried out according to B.A. Dospekhov (2014) and G.F. Lakin (1990). It was found that the average fruit weight of cherry varieties varied not significantly - from 2.72 to 6.45 g, which was confirmed by the coefficient of variation (23.3 %). Indicators of maximum and minimum fruit weight varied significantly in varieties, coefficients of variation were 27.2 and 29.7 %, respectively. The following cherry varieties with large fruits were identified: Timati, Igrushka, Duk Ivanovna, Duk Khodosa, Prizvaniya and Svetlaya. were distinguished. Cherry varieties with high sugar content in fruits were as follows: Feyа, Dzhusi Frut and Igrushka. Feyа, Duk Khodosa, Prizvanie, Svetlaya and Dzhusi Frut had fruits with low acidity; Feyа, Dzhusi Frut and Igrushka fruits were characterized by high content of soluble solids in fruits. Feyа, Igrushka and Duk Khodosa fruits had the highest content of vitamin C; Igrushka, Duk Khodosa, Prizvanie, Svetlaya and Dzhusi Frut were rich in Vitamin P; Duk Khodosa, Prizvanie, Dzhusi Frut and Duk Ivanovna had the largest anthocyanin content. Therefore, Igrushka and Duk Khodosa cherry varieties are recommended for growing in the southern Russia and breeding for improvement of fruit quality.

The effects of arbuscular mycorrhizal fungi and deficit irrigation on the yield and sugar content of watermelons (Citrullus lanatus)

Many studies have demonstrated that arbuscular mycorrhizal fungi (AMF) and deficit irrigation (DI) have positive effects on the fruit yield or quality. This study aims to test whether the watermelon sugar content and yield can be improved by appropriate amounts of AMF and DI methods and to clarify the underlying physiological mechanism. Diploid and triploid watermelon cultivars and their pumpkin rootstock-grafted seedlings were treated with AMF, DI and DI + AMF in a randomised complete block design with five replications. The results showed that DI significantly reduced the relative water content (RWC), PN, alkaline α-galactosidase activity, but increased the insoluble acid invertase (IAI), sucrose synthase (SuSy) and sucrose phosphate synthase (SPS) activities compared with the well-watered (WW) treatment, which led to a decrease in the fruit yield and an increase in the fruit sugar content. Although the AMF improved the RWC, PN and alkaline α-galactosidase, IAI, SuSy and SPS activities in all the watermelon lines under both the DI and WW conditions, the improvement magnitude of these parameters was more pronounced in the pumpkin-root watermelon lines than the corresponding own-root watermelon lines, especially under the DI condition. The integrated application of AMF and DI increased the fruit yield to a level similar to the WW value in the pumpkin-root watermelon lines and sugar content to an optimal level in all the watermelon lines.

The influence of biostimulants on strawberries yield, nutritional and sensory fruit quality

The study was conducted as open field trial, with irrigation, with the Clery strawberry variety. The aim of the study was to investigate the effect of foliar application on berry and seaweed extract on the yield and quality of strawberry fruit (sugar, acid and anthocyanin content). The experiment was set up by random block system in 4 repetitions. The following treatments were applied to the strawberry crop: 1. control, 2. conventional NPK fertilization (10-52-10), 3. 30% reduced conventional NPK fertilization, 4. 30% reduced conventional fertilization + biostimulants. Due to arid growing conditions, NPK fertilizer was applied foliarly. Statistical analysis of the data showed significant differences between treatments in strawberry yield, and anthocyanins content. Compared to the control, the biostimulator had an effect on strawberry yield and total anthocyanin content, but not on the total soluble sugar and acid content of strawberry fruit.

Plasma Membrane-Localized Transporter MdSWEET12 Is Involved in Sucrose Unloading in Apple Fruit.

Sugar content is an important factor determining the flavor in apple fruit. Sugar unloading is a prerequisite step for sugar accumulation. However, little is known about sugar unloading mechanisms in apple. Transcriptomic sequencing of two apple varieties, "Envy" and "Pacific Rose," with significantly different sugar content was performed. MdSWEET12a from the SWEET transporter family was differentially expressed. Further study of the MdSWEET12a showed that this plasma membrane-localized transporter protein-encoding gene was mainly expressed in sieve element-companion cells (SE-CC) in the fruit, which was positively correlated with the sucrose accumulation during the development of "Envy" apple. Consistently manipulating the gene expression through either transient overexpression or silencing significantly increased or decreased the sugar content in apple fruit, respectively. Complementary growth experiments in mutant yeast cells indicated that MdSWEET12a transported sucrose. Heterologous expression of MdSWEET12a in tomato increased the expression of genes related to sugar metabolism and transport, leading to increased sugar content. These findings underpin the involvement of MdSWEET12a in sugar unloading in apple fruit.

Soilless cultivation of ‘Ruby Star’ passion fruit: Effects of NO3-N application, pH, and temperature on fruit quality

• Passion fruit water uptake increased up to 32 L plant –1 week –1 at harvest time. • NO 3 -N absorption ranged from 203 to 267 mg plant –1 day –1 during flowering and harvest. • NO 3 -N concentration of 170 ppm and pH 4–5 result in optimal fruit quality. • High temperature delayed fruit maturity and decreased fruit sugar content and acidity. • Optimal daily mean temperature for producing high-quality fruit was 27–29°C. This study aimed to develop a nutrient solution management protocol to produce a high quality passion fruit using soilless culture. In this study, a two-year experiment was conducted using three levels of electrical conductivity (EC) (1.6, 2.0, and 2.6 dS m –1 ) of the nutrient solution in the first year, and three levels of pH (4, 5, 6) of the nutrient solution in the second year. Although no significant differences were detected in the above-ground dry matter weight, yield, and total soluble solids (TSS) of fruit juice of plants cultivated under different EC and pH conditions, dry matter weight tended to increase under pH 4 condition. The total NO 3 -N absorption increased in plants cultivated in EC 2.6, whereas absorption after pruning back the fruit-bearing vines was not significantly different as affected by EC 2.0 or EC 2.6. A nutrient solution with EC 2.0 and pH 4–5 containing 170 ppm NO 3 -N was found to be optimal for fruit quality. Higher air temperatures delayed fruit maturity and decreased TSS and titratable acidity of the juice, indicating that the optimal daily mean temperatures after flowering were 27–29°C for reliably producing high-quality fruit with a high sugar/acid ratio (≥6.0).

Genetic Stability Assessment of Six Cryopreserved Strawberry (Fragaria × ananassa Duch.) Accessions by Phenotypic and Molecular Studies.

For the long-term preservation of genetic resources, cryopreservation techniques have been developed for strawberry germplasm, mainly using in vitro-grown shoot tips. In this study, genetic stability was tested under greenhouse conditions for six strawberry accessions (IT232511, PHS0132, IT245810, IT245830, IT245852, and IT245860) derived from the following procedures: (1) conventional propagation (GH: greenhouse maintained); (2) in vitro propagation (TC: tissue culture); (3) pretreatment before cryopreservation (-LN: non-liquid nitrogen exposure); and (4) cryopreservation (+LN: liquid nitrogen exposure). To test the performance of phenotypic traits, we measured six vegetative and five fruit traits. There were no distinct differences in most of the characteristics, but a few traits, such as sugar content and pH of fruits in three accessions, showed higher values in +LN compared to GH. However, the differences disappeared in the first runner generation. To test genetic variations, a total of 102 bands were generated by twelve inter simple sequence repeat (ISSR) primers. A few polymorphic bands were found only in plants derived from TC of IT245860, which was not cryopreserved. The sequencing analysis of four polymorphic bands produced by ISSR_15 showed that none of these sequences matched the characterized genes in NCBI. Phenotypic abnormality was not observed across all plants. This study indicates that cryopreserved plants of the six strawberry accessions are phenotypically and genetically stable. Therefore, the results of this study can help to implement cryobanking of strawberry germplasm.

Pan-genome and multi-parental framework for high-resolution trait dissection in melon (Cucumis melo).

Linking genotype with phenotype is a fundamental goal in biology and requires robust data for both. Recent advances in plant-genome sequencing have expedited comparisons among multiple-related individuals. The abundance of structural genomic within-species variation that has been discovered indicates that a single reference genome cannot represent the complete sequence diversity of a species, leading to the expansion of the pan-genome concept. For high-resolution forward genetics, this unprecedented access to genomic variation should be paralleled and integrated with phenotypic characterization of genetic diversity. We developed a multi-parental framework for trait dissection in melon (Cucumis melo), leveraging a novel pan-genome constructed for this highly variable cucurbit crop. A core subset of 25 diverse founders (MelonCore25), consisting of 24 accessions from the two widely cultivated subspecies of C. melo, encompassing 12 horticultural groups, and 1 feral accession was sequenced using a combination of short- and long-read technologies, and their genomes were assembled de novo. The construction of this melon pan-genome exposed substantial variation in genome size and structure, including detection of ~300 000 structural variants and ~9 million SNPs. A half-diallel derived set of 300 F2 populations, representing all possible MelonCore25 parental combinations, was constructed as a framework for trait dissection through integration with the pan-genome. We demonstrate the potential of this unified framework for genetic analysis of various melon traits, including rind color intensity and pattern, fruit sugar content, and resistance to fungal diseases. We anticipate that utilization of this integrated resource will enhance genetic dissection of important traits and accelerate melon breeding.

Efficient A·T to G·C base conversions in dicots using adenine base editors expressed under the tomato EF1α promoter.

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas systems have revolutionized plant breeding. Different Cas enzymes have been widely used to introduce deletions or insertions into plant genomes. However, many important agronomical traits in plants are associated with single nucleotide polymorphisms. For example, the Lin5 SNP causes an Asn366 to Asp change, resulting in a higher sugar content in tomato fruits (Tieman et al., 2017). Thus, it is important to develop tools to efficiently introduce precise base changes in crops.

FveARF2 negatively regulates fruit ripening and quality in strawberry.

Auxin response factors (ARFs) are transcription factors that play important roles in plants. ARF2 is a member of the ARF family and participates in many plant growth and developmental processes. However, the role of ARF2 in strawberry fruit quality remains unclear. In this study, FveARF2 was isolated from the woodland strawberry 'Ruegen' using reverse transcription-polymerase chain reaction (RT-PCR), which showed that FveARF2 expression levels were higher in the stem than in other organs of the 'Ruegen' strawberry. Moreover, FaARF2 was higher in the white fruit stage of cultivated strawberry fruit than in other stage. Subcellular localization analysis showed that FveARF2 is located in the nucleus, while transcriptional activation assays showed that FveARF2 inhibited transcription in yeast. Silencing FveARF2 in cultivated strawberry fruit revealed earlier coloration and higher soluble solid, sugar, and anthocyanin content in the transgenic fruit than in the control fruit, overexpression of FveARF2 in strawberry fruit delayed ripening and lower soluble solid, sugar, and anthocyanin content compared to the control fruit. Gene expression analysis indicated that the transcription levels of the fruit ripening genes FaSUT1, FaOMT, and FaCHS increased in FveARF2-RNAi fruit and decreased in FveARF2-OE fruit, when compared with the control. Furthermore, yeast one-hybrid (Y1H) and GUS activity experiments showed that FveARF2 can directly bind to the AuxRE (TGTCTC) element in the FaSUT1, FaOMT, and FaCHS promoters in vitro and in vivo. Potassium ion supplementation improved the quality of strawberry fruit, while silencing FveARF2 increased potassium ion content in transgenic fruit. The Y1H and GUS activity experiments also confirmed that FveARF2 could directly bind to the promoter of FveKT12, a potassium transporter gene, and inhibited its expression. Taken together, we found that FveARF2 can negatively regulate strawberry fruit ripening and quality, which provides new insight for further study of the molecular mechanism of strawberry fruit ripening.

An Intelligent Near-Infrared Diffuse Reflectance Spectroscopy Scheme for the Non-Destructive Testing of the Sugar Content in Cherry Tomato Fruit

As a new non-destructive testing technology, near-infrared spectroscopy has broad application prospects in agriculture, food, and other fields. In this paper, an intelligent near-infrared diffuse reflectance spectroscopy scheme (INIS) for the non-destructive testing of the sugar contents in vegetables and fruits was proposed. The cherry tomato were taken as the research object. The applicable objects and features of the three main methods of near-infrared detection were compared. According to the advantages and disadvantages of the three near infrared (NIR) detection methods, the experiment was carried out. This experiment involved the near-infrared diffuse reflection detection method, and the back propagation (BP) network model was established to research the sugar content of the cherry tomatoes. We used smoothing and a principal component analysis (PCA) to extract the final spectrum from the experimental spectrum. Taking the preprocessed spectral data as the input of the network and the measured sugar content of the cherry tomatoes as the output, the 80-12-1 network model structure was established. The cross-validation coefficient of determination was 0.8328 and the mean absolute deviation was 0.5711. The results indicate that the BP neural network can quickly and effectively detect the sugar content in cherry tomatoes. This intelligent near-infrared diffuse reflectance spectroscopy (INIS) scheme can be extended and optimized for almost all sugar-containing fruits and vegetables in the future.

Frugivorous bird foraging is related to pericarp color and ultraviolet reflectance in fruiting shrub species

ABSTRACT Seed dispersal by birds is critical for regeneration and maintenance of plant populations. Birds likely rely on both visible light of human’s eyes and ultraviolet (UV) reflectance when foraging for fruit. Fruit color is suggested to be an honest signal that allows birds to assess nutrient status. We assessed UV reflectance and pericarp color as honest indicators of fruit maturity in three fruiting shrubs in Osaka, Japan. We measured sugar content and light spectra in the fruits of Eurya japonica, Ligustrum obtusifolium and Ligustrum japonicum and observed birds foraging on target individuals. We found that a model including fruit color and UV reflection as explanatory variables best explained variation in fruit sugar content in E. japonica and L. obtusifolium, whereas UV reflection alone best explained variation in L. japonicum. Next, we assessed relationships between fruit color and bird foraging behavior and found strong temporal correlation between active foraging and peak sugar content. Bird foraging behavior differed among the three shrub species. This is probably because fruit consumption by birds is not entirely dependent on fruit color or sugar content of the fruits. It must depend on various factors such as the presence of fruiting neighbors of conspecific or heterospecific plants and seasonal variation of population-level or community-level fruit abundance.

Effects of Pollen Sources on Fruit Set and Fruit Characteristics of 'Fengtangli' Plum (Prunus salicina Lindl.) Based on Microscopic and Transcriptomic Analysis.

Adequate yield and fruit quality are required in commercial plum production. The pollen source has been shown to influence fruit set and fruit characteristics. In this study, 'Siyueli', 'Fenghuangli' and 'Yinhongli' were used as pollinizers of 'Fengtangli' plum. Additionally, self-pollination, mixed pollination, and open pollination were performed. We characterized the differences in pollen tube growth, fruit set and fruit quality among pollination combinations. 'Fengtangli' flowers pollinated by 'Fenghuangli' had more pistils with pollen tubes penetrating the ovary and the highest fruit set rate, while the lowest fruit set rate was obtained from self-pollination. In self-pollinated flowers, 33% of pistils had at least one pollen tube reaching the ovary, implying that 'Fengtangli' is partially self-compatible. Pollen sources affected 'Fengtangli' fruit size, weight, pulp thickness, soluble solids, and sugar content. Transcriptome analysis of 'Siyueli'-pollinated and 'Yinhongli'-pollinated fruits revealed 2762 and 1018 differentially expressed genes (DEGs) involved in the response to different pollen sources. DEGs were enriched in plant hormone signal transduction, starch and sucrose metabolism, and MAPK signaling pathways. Our findings provide a reference for the selection of suitable pollinizers for 'Fengtangli' plum and promote future research on the metaxenia effect at the molecular level.

Fungicidal activities and molecular docking of the marine alga Ulva lactuca and Punica granatum peel extracts on Alternaria tomato spot disease.

In this study, we utilized pomegranate peel and marine algae Ulva lactuca (U. lactuca) as rich and sustained sources of bioactive compounds to combat tomato-black spot disease. n-Hexane extracts from the peel of pomegranate (Punica granatum) (PPE) and the marine algal biomass U. lactuca (ULE) were used alone and in combinations to verify their impact against Alternaria alternata (A. alternata). The applied extracts exhibited severe destructive effects on both fungal growth and structure such as mycelia malformation, underdeveloped conidia, cell wall deformation, and shrinkage. Moreover, increased deformations and protrusions, and notch-like structures, were noticed in A. alternata mycelia treated with mixed extracts (PPE and ULE) compared to all other treatments. The protein and reduced sugar contents in tomato fruits were significantly increased in the infected fruits with A. alternata. The highest enzyme activities of pectinase, cellulase, catalase (CAT), and ascorbate peroxidase (APX) were recorded in infected tomatoes in comparison with the healthy ones. Molecular docking studies showed that each extract is rich with bioactive compounds that have a promising inhibition effect on A. alternata cellulases. Pomegranate and Ulva extract showed promising antifungal activity against A. alternata which revealed their feasibility and applicability as biocontrol agents in postharvest disease management and food preservation against fungal pathogens.

Determination of the main fruit chemical indicators of six apple cultivars in the agro-ecological zone of Deçan, Kosovo

Study was conducted during three consecutive years, 2018-2020, in Deçan of Kosovo. There was studied the expression of the main fruit indicators of six new planted apple cultivars. Mean fruit weight varied from 93.3 g (Gold Delicious clone B) to 184.2 g (Jonagored). Saturn apple cultivar produced the largest size fruit (80 x 84 mm), while Montear Gala produced the lowest size fruit (58 x 70 mm). Fruit dry matter content varies from 14.6% (Saturn and Montear Gala cultivars) to 16.5% (Royal Gala), and 16.7% (Gold Delicious clone B). Fruit sugar content varies from 11.33% (Royal Gala) to 12.7% (Saturn). Total fruit acidity varies from 0.250 mg/100 g fresh fruit (Saturn) to 0.395 mg/100 g fresh fruit (Royal Gala). There were found significative differencies between cultivars for the main tested fruit indicators. There was found a significative relationship between some fruit indicators, as well.

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.