Affect Fruit Quality Research Articles

Integrated transcriptomic and proteomic analysis reveals the complex molecular mechanisms underlying stone cell formation in Korla pear

Korla pear (Pyrus sinkiangensis Yü) is a landrace selected from a hybrid pear species in the Xinjiang Autonomous Region in China. In recent years, pericarp roughening has been one of the major factors that adversely affects fruit quality. Compared with regular fruits, rough-skin fruits have a greater stone cell content. Stone cells compose sclerenchyma tissue that is formed by secondary thickening of parenchyma cell walls. In this work, we determined the main components of stone cells by isolating them from the pulp of rough-skin fruits at the ripening stage. Stone cell staining and apoptosis detection were then performed on fruit samples that were collected at three different developmental stages (20, 50 and 80 days after flowering (DAF)) representing the prime, late and stationary stages of stone cell differentiation, respectively. The same batches of samples were used for parallel transcriptomic and proteomic analysis to identify candidate genes and proteins that are related to SCW biogenesis in Korla pear fruits. The results showed that stone cells are mainly composed of cellulose (52%), hemicellulose (23%), lignin (20%) and a small amount of polysaccharides (3%). The periods of stone cell differentiation and cell apoptosis were synchronous and primarily occurred from 0 to 50 DAF. The stone cell components increased abundantly at 20 DAF but then decreased gradually. A total of 24,268 differentially expressed genes (DEGs) and 1011 differentially accumulated proteins (DAPs) were identified from the transcriptomic and proteomic data, respectively. We screened the DEGs and DAPs that were enriched in SCW-related pathways, including those associated with lignin biosynthesis (94 DEGs and 31 DAPs), cellulose and xylan biosynthesis (46 DEGs and 18 DAPs), S-adenosylmethionine (SAM) metabolic processes (10 DEGs and 3 DAPs), apoplastic ROS production (16 DEGs and 2 DAPs), and cell death (14 DEGs and 6 DAPs). Among the identified DEGs and DAPs, 63 significantly changed at both the transcript and protein levels during the experimental periods. In addition, the majority of these identified genes and proteins were expressed the most at the prime stage of stone cell differentiation, but their levels gradually decreased at the later stages.

Advances in Mineral Nutrition Transport and Signal Transduction in Rosaceae Fruit Quality and Postharvest Storage.

Mineral nutrition, taken up from the soil or foliar sprayed, plays fundamental roles in plant growth and development. Among of at least 14 mineral elements, the macronutrients nitrogen (N), potassium (K), phosphorus (P), and calcium (Ca) and the micronutrient iron (Fe) are essential to Rosaceae fruit yield and quality. Deficiencies in minerals strongly affect metabolism with subsequent impacts on the growth and development of fruit trees. This ultimately affects the yield, nutritional value, and quality of fruit. Especially, the main reason of the postharvest storage loss caused by physiological disorders is the improper proportion of mineral nutrient elements. In recent years, many important mineral transport proteins and their regulatory components are increasingly revealed, which make drastic progress in understanding the molecular mechanisms for mineral nutrition (N, P, K, Ca, and Fe) in various aspects including plant growth, fruit development, quality, nutrition, and postharvest storage. Importantly, many studies have found that mineral nutrition, such as N, P, and Fe, not only affects fruit quality directly but also influences the absorption and the content of other nutrient elements. In this review, we provide insights of the mineral nutrients into their function, transport, signal transduction associated with Rosaceae fruit quality, and postharvest storage at physiological and molecular levels. These studies will contribute to provide theoretical basis to improve fertilizer efficient utilization and fruit industry sustainable development.

Preharvest sprays with sodium nitroprusside induce resistance in harvested muskmelon against the pink rot disease

Pink rot caused by Trichothecium roseum is an important postharvest disease of muskmelon, and caused very serious postharvest losses. In this study, sodium nitroprusside (SNP), an exogenous nitric oxide donor, was applied four times during fruit development to muskmelon. The effect of SNP sprays on pink rot in harvested fruit and the influence on the mechanism of antioxidant enzymes and the phenylpropanoid pathway were investigated. The results showed that SNP sprays significantly reduced decay incidence and lesion area of muskmelon inoculated with T. roseum. SNP sprays induced the production of H2O2 in fruit at harvest, maintained cell membrane integrity, and increased the activity of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase during storage. In addition, SNP sprays also increased the activity of phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, and 4-coumaroyl-CoA ligase, and promoted the accumulation of total phenolic, flavonoid, and lignin content in harvested muskmelon at harvest and during storage. These results suggesting a new possible way of prevention of postharvest pathogens. Practical applications Muskmelon is an important cash crop in the world, due to its unique appearance and intrinsic quality. However, postharvest losses of the muskmelon fruit are serious. Pink rot caused by Trichothecium roseum is one of the main reasons for the postharvest losses of harvested muskmelon. SNP preharvest sprays effectively induced the resistance and reduced decay incidence and lesion area of muskmelon inoculated with T. roseum. Compared with the postharvest treatment, which involves complete exposure, preharvest sprays not only affects the fruit, but also other portions of the plants, which could indirectly affect fruit quality. In addition, the preharvest treatment operation is simple and convenient, and the control effect is better than the postharvest treatment. Therefore, this work may provide a new approach for the control of postharvest diseases of muskmelon.

Quantitative proteomic analysis of pear (Pyrus pyrifolia cv. "Hosui") flesh provides novel insights about development and quality characteristics of fruit.

A total of 6763 proteins were identified in the developing pear flesh, which were further screened for differentially expressed proteins related to fruit quality and ATP-binding cassette transporters. To obtain further details on changes in protein levels during fruit ripening and to identify and evaluate changes in various metabolic pathways that affect fruit quality, a proteomic method using tandem mass tags was implemented at three developmental stages in Pyrus pyrifolia cv. "Hosui" that identified 6763 proteins. Subcellular localization and Gene Ontology enrichment analysis revealed major functions of all identified proteins. Kyoto Encyclopedia of Genes and Genomes pathway analysis suggested that all metabolic processes are reflected in the up- and downregulation of differentially expressed proteins during fruit development, which play predominant roles in cell division, cell expansion, and fruit ripening. Among the examined differentially expressed proteins, 160 related to fruit quality, and 14 ATP-binding cassette transporters related to fruit development were identified and analyzed. The quantitative data were validated by parallel reaction monitoring, which confirmed the reliability of the experimental results.

Effects of vermicompost fertilization on soil, tomato yield and quality in greenhouse.

The excessive use of chemical fertilizer on vegetables in protected facilities resulted in soil degradation, serious soil-borne diseases, and lower vegetable yield and quality. We examined the effects of vermicompost on soil nutrient, enzyme activities, microbial quantity, tomato growth, yield and quality in greenhouse. The results showed that both broadcast and furrow application of vermicompost improved soil environment, and significantly increased contents of soil organic matter and soil nutrients (nitrogen, phosphorus and potassium). Vermicompost application significantly increased sucrase and catalase activities, abundance of bacteria and actinomycetes, and decreased the abundance of fungi in the soil. Furrow application but not the broadcast application promoted the growth of tomato plants. The vermicompost promoted root activities and leaf photosynthesis, increased chlorophyll, nitrogen and potassium contents in leaves. Broadcast and furrow application of vermicompost significantly increased tomato yield by 22.7% and 32.6%, respectively. Furrow application increased the contents of soluble protein, soluble sugar, vitamin C and titratable acid by 66.1%, 11.0%, 122.6% and 29.9%, respectively, and decreased nitrate content in tomato fruits by 65.7%. However, broadcast application did not affect fruit quality.

Using artificial neural network in predicting the key fruit quality of loquat.

The formation and regulation of loquat fruit quality have always been an important research field to improve fruit quality, commodities, and market value. Fruit size, soluble solids content, and titratable acid content represent the most important quality factors in loquat. Mineral nutrients in abundance or deficiency are among the most important key factor that affect fruit quality. In the present study, we use artificial neural network (ANN) to explore the effects of mineral nutrients in soil and leaves on the key fruit quality of loquat. The results show that the ANN model with the structure of 12–12–1 can predict the single fruit weight with the highest accuracy (R 2 = .91), the ANN model with the structure of 10–11–1 can predict the soluble solid content with the highest accuracy (R 2 = .91), and the ANN model with the structure of 9–10–1 can predict the titratable acid content with the highest accuracy (R 2 = .95). Meanwhile, we also conduct sensitivity analysis to analyze the relative contribution of mineral nutrients in soils and leaves to determine of the key fruit quality. In terms of relative contribution, Ca, Fe, and Mg content in soils and Zn, K, and Ca content in leaves contribute relatively largely to a single fruit weight, Mn, Fe, and Mg content in soils and the N content in leaves contribute relatively largely to the soluble solid content, and the P, Ca, N, Mg, and Fe in leaves contribute relatively largely to the titratable acid content of loquat. The established artificial neural network prediction models can improve the quality of loquat fruit by optimizing the content of mineral elements in soils and leaves.

Dose effect of exogenous abscisic acid on controlling lignification of postharvest kiwifruit (Actinidia chinensis cv. hongyang)

Postharvest ‘Hongyang’ fruit is susceptible to low temperature in storage, which results in black patches on the peel and lignification in the pulp. Abscisic acid (ABA) has been shown to enhance the cold tolerance of many other postharvest fruits. This study investigated whether applying ABA can control chilling injury (CI) of ‘Hongyang’ during storage at 0 °C. Fruit were pretreated with 0–50 mg/L ABA, and then the CI symptoms and lignin accumulation processes were analyzed and microscope observations were performed during low temperature storage. The results showed that there is dose effect on controlling lignification. For example, 50 mg/L ABA treatment increased phenylalanine ammonialyase (PAL), cinnamyl alcohol dehydrogenase (CAD) and peroxidase (POD) activity, which are crucial for lignin synthesis, and sharply upregulated expression of the AcPAL, AcCAD and AcPOD genes. However, 20 mg/L ABA alleviated black patch symptoms, increased lignin content in the peel, and did not negatively affect fruit quality. The higher total antioxidant capacity (ORAC) of edible part was maintained by 20 mg/L ABA treatment. Furthermore, microscope observations showed that 20 mg/L ABA decreased the number of lignin cells with a diameter of 40–80 μm, thus reducing the chance of lignification in the pulp.

Fruit Thinning and Physiological Disorders in Citrus Variety ‘Harumi’

Citrus ‘Harumi’ is a mandarin-type cultivar and shows a wide range of fruit size, which affects fruit quality such as sugar and acid contents. In citrus, fruit size also affects the degree of physiological disorder which become a big problem during storage. Thus, making fruit with equal and appropriate size is very important. Fruit thinning is one of the most important techniques to adjust fruit size by controlling the fruit number. Basically, fruit thinning has been conducted using a criterion based on leaf and fruit ratio (L/F) or fruit number per canopy volume. In this review, several thinning criteria for ‘Harumi’ and other citrus varieties are compared, and the pros and cons are discussed. In some citrus varieties, storage is necessary to adjust shipping time. During the storage, some physiological disorders occurred in peel, flesh and whole fruit. The occurrence of physiological disorders was influenced by citrus variety, fruit size and environmental conditions during storage. In ‘Harumi’ which is classified to easy-peeling variety, small fruit showed serious weight loss and peel wrinkle, while rind puffing and dehydration of flesh were big problems in large fruit during storage. Polyethylene (PE) bag wrapping has been used to decrease the fruit weight loss and to prevent the occurrence of some physiological disorders in tight-skin citrus varieties. However, the influences of PE wrapping on easy-peeling citrus is unclear. In this study, the researches on storage conditions, feature, and cause of physiological disorders during storage are also reviewed, and the effects of PE wrapping are discussed to improve storage condition in ‘Harumi’.

Effect of Postharvest Methyl Jasmonate Treatment on Early-Matured “Hass” Avocado Fruit Exocarp Colour Development during Ripening

Poor exocarp colour development is a common postharvest problem for early harvested “Hass” avocado fruit during ripening, which affects fruit quality and consumer preference. Therefore, measures to improve “Hass” avocado fruit colour developments are of great importance in the industry. This study investigated the effectiveness of postharvest methyl jasmonate treatment to improve early matured “Hass” avocado fruit exocarp colour during ripening. The results showed that T1 (10 μmol∙L−1) and T2 (100 μmol∙L−1) MeJA treatment increased visual colour, and decreased objective colour parameters (L*, C* and h˚) during ripening when compared with control fruit. Moreover, MeJA treated “Hass” avocado fruits had lower total chlorophyll content and higher total anthocyanin and cyanidin-3-O-glucoside concentration during ripening. In conclusion, “Hass” avocado fruit post-harvest treated with either T1 (10 μmol∙L−1) or T2 (100 μmol∙L−1) MeJA concentration improved exocarp quality attributes such as colour parameters (L*, C* h˚ and visual colour) and pigments (total anthocyanin and cyanidin-3-O-glucoside) during ripening, therefore, can be recommended for avocado fruit.

Fertilization and precise irrigation scheduling for mature avocado

Irrigation scheduling (IS) and fertilization are among the most important practices in the production of horticultural crops because they affect fruit quality and quantity directly. Thus, a 15-year-old avocado orchard (cv. ‘Simmonds’) was used to determine precise IS, based on monitoring soil moisture content (SMC), remote sensing technologies [Unmanned Aerial Vehicle (UAV)] under two fertilization levels using granular formulation 15-3-19. In October 2015, all trees were pruned (topped and hedged) to 3.05 m height and 2.44 m diameter. In December 2015, soil moisture (SM) sensors were installed at five (10, 30, 50, 70 and 90 cm) soil depths in six locations. Trees received two fertilizer treatments: F1-9.06 kg and F2-12.07 kg of 15-3-19/tree/year every three months. Precipitation and SM data were recorded daily for 21 months; SM data was corrected with a quadratic equation (y = -4.1881x2 + 3.6886x - 0.3083) generated specifically for the Coto soil series (Typic Hapludox). The SM values recorded were always greater than 41%, indicating that the avocado orchard was growing under water saturation conditions; thus, micro-irrigation was not needed. The UAV data at 5, 13 and 20 months after pruning (MAP) showed quick closure of the avocado canopy; acquiring a denser and more cylindrical shape (from 17.6 ± 2.65 m2 to 52.7 ± 6.10 m2), regardless of fertilizer level. Based on correlation of UAV and manual results, F2-treated trees indicated stronger correlation at 13 and 20 MAP (R2 >0.75) than F1-trees. Yield production (110 avocados per tree = 13,200 per hectare) and leaf nutrient content did not differ significantly with fertilizer level. For commercial avocado farmers the use of SMC sensors and UAV technology could be an advantage, albeit an expensive one. Soil moisture content sensors have been shown to be very effective in irrigation water conservation. In terms of fertilization, the results suggest not using more than 9.06 kg of 15-3-19/tree/year as this amount seems enough to satisfy avocado requirements, under the experiment’s conditions. Future evaluations will determine if it is possible to use less fertilizer and still maintain an optimal avocado production.

Industrial applications of selected JFS articles

Industrial applications of selected <i>JFS</i> articles

Evaluation of postharvest properties in different passion fruit species during ripening

During ripening, many transformations occur in passion fruits. The ripening stage affects fruit quality and post-harvest properties. Fruits with 65% yellow epidermis present chemical characteristics that meet industrial standards, facilitating harvest estimations and loss avoidance. Thus, this study aimed to evaluate the post-harvest properties of passion fruit species (genotypes of the yellow passion fruit and sweet passion fruit, and yellow passion fruit cultivar FB 200) during ripening. The fruits were evaluated by the color of the epidermis and the chemical characteristics of the pulp (titratable acidity, vitamin C, carotenoids, soluble solids content, and ratio). This experiment was conducted with a completely randomized design and a split-plot arrangement, where the plots were the species and the subplots were the evaluation periods (50, 58, 66, 74 and 82 days after anthesis), with four replications and 10 fruits per plot. The yellow passion fruit genotype and cultivar, harvested at 82 days after anthesis, presented desirable characteristics for the juice industry and for fresh consumption. The sweet passion fruit had a higher soluble solids content and titratable acidity ratio because of its high content of soluble solids and low acidity, which translate to a better fruit flavor.

Analysis and Optimization of the Effects of Meteorological Factors on ‘Fuji’ Fruit Quality in Two Dominant Production Regions of China

This study aimed to understand the effects of meteorological factors on the ‘Fuji’ apple quality in the Circum-Bohai and Loess Plateau apple production regions of China and to guide apple production based on local climate. Fruit samples of the ‘Fuji’ apple and meteorological data were investigated from 132 commercial ‘Fuji’ apple orchards covering 44 counties in the two aforementioned production regions (22 counties per region). The partial least-squares regression (PLSR) method was first used to screen major meteorological factors that greatly affected fruit quality; these were subsequently used to establish the regression equation of fruit quality attributes and major meteorological factors. Linear programming was used to estimate optimum meteorological factors for good apple quality. The results showed that in the Circum-Bohai production region, many meteorological factors (total annual precipitation, total precipitation from April to October, lowest temperature from April to October, sunshine percentage from April to October) were significantly higher than those in the Loess Plateau production region; however, the temperature difference between day and night from April to October was significantly smaller than that in the Loess Plateau production region. The soluble solids content and skin color area of apples from the Loess Plateau production region were significantly greater than those from the Circum-Bohai production region. The same fruit quality factor of ‘Fuji’ apple was affected by different meteorological factors in the two production regions. The monthly mean temperature and monthly highest temperature from April to October of the Circum-Bohai production region had relatively larger positive effect weights on fruit quality, whereas the total annual precipitation, monthly mean relative humidity from April to October, and total precipitation from April to October of the Loess Plateau production region had relatively larger positive effect weights on fruit quality. The major influencing meteorological factors of the fruit soluble solids content were total precipitation from April to October (X7), mean annual temperature (X1), and the monthly highest temperature from April to October (X5) in the Circum-Bohai production region; however, it included the monthly mean temperature difference between day and night from April to October (X6), total annual precipitation (X2), and total precipitation from April to October (X7) in the Loess Plateau production region. In the Circum-Bohai production region, the optimum meteorological factors for ‘Fuji’ fruit quality of vigorous apple orchards were the mean annual temperature (13.4 °C), total annual precipitation (981 mm), monthly mean temperature (16.8 to 22.4 °C), lowest temperature (11.9 °C), highest temperature (19.5 to 26.8 °C), temperature difference between day and night (12.3 °C), total precipitation (336–793 mm), relative humidity (55.7% to 70.7%), and sunshine percentage (42.3% to 46.1%) during the growing period (April–October). In the Loess Plateau production region, the optimum meteorological factors for ‘Fuji’ fruit quality of vigorous apple orchards were the mean annual temperature (5.5 to 11.6 °C), total annual precipitation (714 mm), monthly mean temperature (13.3 to 19.9 °C), lowest temperature (7.9 to 9.3 °C), highest temperature (19.6 to 27.3 °C), temperature difference between day and night (7.1 to 12.4 °C), total precipitation (338–511 mm), relative humidity (56.1% to 82.4%), and sunshine percentage (37.3% to 55.9%) during the growing period (April–October). The restrictive factors for high-quality ‘Fuji’ apples of the Circum-Bohai production region were the smaller monthly mean temperature difference between day and night, higher monthly mean lowest temperature, and larger monthly mean relative humidity during the growing period; however, those of the Loess Plateau production region were drought or less precipitation from November to March, lower monthly mean temperature, and higher monthly mean highest temperature during the growing period.

Irrigation water of different sources affects fruit quality attributes and heavy metals contents of un-grafted and commercial mango cultivars

In peri-urban areas, waste water is used to irrigate orchards due to scarcity of fresh water which increases heavy metals contents in soils, leaves and fruits. Due to excessive waste water irrigations, heavy metals enter into the food chain, which eventually causes metabolic disorders in humans. The present study was envisaged to investigate the effects of canal, tubewell and sewage water on the quality of mango fruits and heavy metals accumulation in soils, leaves and fruits. Leaf and fruit samples from an un-grafted (Desi mango) and six commercial cultivars of mango (Anwar Rataul, Aman Dusehri, Sufaid Chaunsa, Samar Bahisht Chaunsa, Kala Chaunsa and Anwar Rataul Late) grafted on Desi mango were collected from different mango orchards located in peri-urban areas of Multan (Pakistan) and analyzed for some physico-chemical attributes and heavy metals contents. Soil samples were also taken from these orchards irrigated with different water sources to assess the soils' heavy metals status. A significant variation was observed among the mango cultivars for their physico-chemical attributes. Sewage water irrigation improved total soluble solids (TSS), titratable acidity, ascorbic acid content, total phenolics, total carotenoids, total flavonoids and antioxidant activity of mango fruits. However, it did not affect fruit weight and shelf life. Among the heavy metals, copper and nickel contents were found in greater amounts in soils, leaves and fruits of sewage water irrigated orchards than canal and tubewell water irrigated ones. However, zinc and cadmium were not detected in any soil, water, leaf or fruit sample. The interaction among the sources of irrigation and the mango cultivars was significant for copper accumulation in different soil layers, copper and nickel accumulation in leaves of different mango cultivars, and fruit weight, titratable acidity, ascorbic acid content, total flavonoids and shelf life of mango fruits.

Metabolite alteration in response to low phosphorus stress in developing tomato fruits

Alteration of fruit quality caused by environmental stress is a common but largely unresolved issue for plant cultivation and breeding practices. Phosphorus (P) deficiency may interfere with a variety of metabolic processes whose intermediate products are correlated with important fruit quality traits. However, how low P stress affects fruit quality has not been investigated in detail. In this study, we assessed the contents of major metabolites associated with tomato fruit quality under two low P treatments that started at the seedling or flowering stage. The major pigments and the key organic acids related to fruit sourness were differentially over-accumulated as fruit ripened under two low P treatments compared to those under the control treatment, while the total content of soluble sugars contributing to fruit sweetness was substantially reduced under both treatments. These changes were largely attributed to the alteration of enzyme activities in the relevant metabolic pathways. In particular, we found that low P stress from different developmental stages had differential effects on the activation of γ-aminobutyric acid shunt that were likely responsible for the preferential accumulation of different organic acids in tomato fruits. Our study suggested that low P stress strongly affected tomato fruit quality and the effects appeared to be variable under different regimes of low P conditions.

Photoselective Protective Netting Improves "Honeycrisp" Fruit Quality.

High temperatures, wind, and excessive sunlight can negatively impact yield and fruit quality in semi-arid apple production regions. Netting was originally designed for hail protection, but it can modify the light spectrum and affect fruit quality. Here, pearl, blue, and red photoselective netting (≈20% shading factor) was installed in 2015 over a commercial “Cameron Select® Honeycrisp” orchard. Our research objectives were to (1) describe the light quantity and quality under the colored nets compared to an uncovered control and (2) investigate the effect of Photoselective nets on “Honeycrisp” apple quality for two growing seasons. Light transmittance and scattering for each treatment were measured with a spectroradiometer, and samples for fruit quality analyses were collected at harvest. PAR (photosynthetic active radiation), UV, blue, red, and far-red light were lower underneath all netting treatments compared to an uncovered control. The scattered light was higher under the pearl net compared to other colors, while red and far-red light were lower under the blue net. For two consecutive years, trees grown under the photoselective nets intercepted more incoming light than the uncovered trees with no differences among the three colors. In both years, trees under red and blue nets had more sunburn-free (clean) apples than pearl and control. Red color development for fruit was lower when nets were used. Interestingly, bitter pit incidence was lower underneath red nets for both years. Other than red color development, “Honeycrisp” fruit quality was not appreciably affected by the use of netting. These results highlight the beneficial effect of nets in improving light quality in orchards and mitigating physiological disorders such as bitter pit in “Honeycrisp” apple.

Response of fruit set and quality and seed formation to ploidy levels of pollen donor in yellow-fleshed kiwifruits

This study investigated how the ploidy level of the kiwifruit pollinizer cultivars “CK3” (diploid), “T line” (tetraploid), “Pohwa” (hexaploid) and “Chieftain” (hexaploid) affected fruit set, fruit quality, and seed formation in the tetraploid kiwifruit cultivars “Halla Gold” and “Sweet Gold” cultivated in an unheated greenhouse in Jeju, Korea. Pollen tubes growing in the pistil reached and combined with the ovule 3 days after artificial pollination, and their patterns differed depending on the ploidy level of the pollen parent. The number of pollen tubes observed in “Halla Gold” and “Sweet Gold” pistils was significantly lower following pollination by “CK3” than with the other pollen donors. In all pollen treatments, the fruit set rates were > 90%. The fruit weight of both “Halla Gold” and “Sweet Gold” were high following pollination with “Chieftain” and “Pohwa”. The dry matter content, soluble solids, and acidity were not significantly different among all pollination treatments. Fruit firmness was higher following pollination with “Chieftain” and “Powha.” Colorimeter h˚ values for flesh of “Halla Gold” was low following pollination with “CK3,” but there were no differences for “Sweet Gold” among all pollinations. The number of seeds showed a similar trend to fruit weight, but the 100-seed weight was highest with “T line” as the pollinizer. The results indicate that the ploidy level of the pollen donor affects fruit quality more than fruit set. Also, the pollen most suitable for cultivation of “Halla Gold” and “Sweet Gold” is considered to be tetraploid “T line” and hexaploid “Pohwa” and “Chieftain,” which showed favorable effects on the weight and firmness of fruits, and the number and weight of seeds without adversely influencing fruit set and dry matter content.

Effect of electron beam radiation on disease resistance and quality of harvested mangoes

Postharvest disease is a major problem in mangoes, affecting fruit quality, reducing shelf life and negatively impacting exports. To minimize the disease and maintain fruit quality, the effect of electron beam (E-beam) radiation on anthracnose disease, plant defense enzymes, and fruit quality was investigated. Mango fruit cv. Nam Dok Mai Si-Thong was exposed to an E-beam of 0.5 kGy and stored at 13 °C for 16 d. Non-exposed fruit served as the control. The E-beam treatment demonstrated reduction of disease incidence and severity by inducing the accumulation of hydrogen peroxide and the activities of plant defense enzymes such as peroxidase, β-1, 3-glucanase, and chitinase during late storage except for phenylalanine ammonia-lyase, and did not affect the accumulation of the total phenolic content. The respiration rate and ethylene production of the fruit increased immediately after, triggered by E-beam treatment. Later, the respiration rate was significantly suppressed compared to those fruit with non-treatment until the end of storage. The treatment significantly maintained fruit quality with regard to firmness, slowdown in decrease of titratable acid, and retardation in the increase of total soluble solids; however, it did not affect vitamin C content. This is a preliminary experiment to establish that E-beam can alleviate postharvest disease development via hydrogen peroxide and the activities of plant defense enzymes while maintaining fruit quality.

Understanding the key preharvest factors determining ‘Packham’s Triumph’ pear heterogeneity and impact in superficial scald development and control

Abstract Although superficial scald (SS) is well characterized on apples, there is still few information regarding the influence that initial fruit’s maturity heterogeneity may have on the development of this disorder on pears. In this study we aimed to understand the effect of growing season and site, harvest maturity, and their interaction with postharvest treatments on superficial scald development. Pears (Pyrus communis L.) cv ‘Packham’s Triumph’ were picked during three consecutive seasons at three harvest maturities (H1, H2, H3) from different commercial orchards. Different SS control treatments (DPA vs. 1-MCP; season # 2) and storage scenarios (RA, CA and RA + stepwise cooling (SWC); season # 3) were evaluated. Bioclimatic indices, superficial scald incidence, maturity indices and biochemical analysis associated with SS were carried out at harvest and periodically postharvest in all treatments. In general, bioclimatic indexes (GDA and HL10) were poorly correlated with SS incidence. Only in season #1, harvest maturity was positively correlated with SS after 140 and 180 d into storage (rs = 0.621* and 0.620*, respectively), the more mature fruit being more sensitive. The opposite was observed in season #3, and no pattern in season #2. There was a good and positive correlation between CTols dynamic (δCTols/δt) and SS development, with variation between seasons. DPA and 1-MCP effectively reduced SS up to 180 d regardless of years and orchard location. In contrast, the beneficial effect of CA storage was orchard dependent and SWC strategy did not control SS and affected fruit quality. Collectively our results suggest that initial fruit heterogeneity at harvest is an important factor that modulate SS development in ‘Packham triumph pears. Climatic and fruit maturity indexes are not reliable for a multi-year prediction of SS development. In contrast to CA storage that reduced the disorder in an orchard dependent manner, 1-MCP and DPA treatments effectively controlled SS independently of initial fruit heterogeneity.

Elevated temperature and drought stress significantly affect fruit quality and activity of anthocyanin-related enzymes in jujube (Ziziphus jujuba Mill. cv. 'Lingwuchangzao').

The quality attributes of jujube fruit can be directly and indirectly affected by abiotic stresses associated with climate change. Increased temperature and drought are among the most important factors challenging sustainable jujube production in the temperate semi-arid region in northwest China. The main objective of the present study was to understand the effects of elevated air temperature and drought stress on sugar and acid accumulation and coloration of jujube fruits. The content of soluble sugar, organic acid and pigments of traditional jujube "Linwuchangzao" under different atmospheric temperatures and drought stresses were analyzed during three different fruit ripening stages. The elevated temperature (1.5–2.5° C than normal temperature) significantly increased the fruit sugar content, sugar-acid ratio, anthocyanins, flavonoids and carotenoids content. Under the drought stress where the soil moisture was 30% -50% of the field capacity, sugar content, anthocyanin, flavonoid and carotenoid content of the fruit were significantly reduced at the same temperature, but the chlorophyll and organic acid content increased. No significant interaction of Temperature x Drought was observed for all the analyzed quality parameters. The current results showed that the fruit quality of jujube variety "Lingwuchangzao" could be improved when the atmospheric temperature increases by 2° C in this region. However, drought stress had a negative impact on the fruit's sugar-acid ratio and pigment content. The present results also showed that the synthesis and accumulation of anthocyanins in jujube fruit were positively correlated with sugar content and related enzyme activities, especially Phenylalanine Ammonia-lyase (PAL) activity. This study, therefore, provides novel information for understanding the influence of growth environment on the quality properties of jujube fruits. This knowledge will help develop appropriate crop management practices for jujube production in arid and semi-arid areas in northwest China.