Days After Full Bloom Research Articles

Seasonal changes of mineral nutrients in the fruit of navel orange plants grafted on trifoliate orange and citrange

To clarify whether the rootstock can affect the uptake dynamics of mineral nutrient in the fruit of navel orange, changes in the concentration and quantities of macronutrients (N, P, K, Mg, and Ca) and micronutrients (B, Fe, Mn, Cu, and Zn) in the fruit of Newhall navel orange grafted on trifoliate orange and citrange were measured at semi-monthly intervals during fruit development. The macronutrients measured in this study, except Ca, decreased in concentration on a whole fruit basis during stage I and then remained constant or decreased very slightly during stages II and III of fruit development. Calcium concentration in whole fruit increased during stage I. The elements Mn, Cu and Zn declined in concentration on a whole fruit basis at two rates, very sharply during early stage I and then gradually in the following days to maturity. An exception to this general pattern was boron, where the concentration remained constant during stage I and early stage II and then decreased slightly. For the element Fe, the concentrations showed a large increase and then declined immediately from 120 to 150 days after full bloom (DAFB). With few exceptions (e.g., Fe, Mn, and Zn), the quantity of each element accumulated increased steadily throughout the growth period to reach a maximum by harvest in both grafted plants. Fe accumulation in whole fruit increased from a minimum just after fruit set to a maximum by 135 DAFB. For a number of elements (N, P, K, B, and Mn), there was a strong linear correlation (R2 > 0.95, P < 0.001) between the dry mass yield and the amount accumulated throughout the growth period. Potassium and N are the two nutrients that accumulated in greatest amounts by fruit. Boron and Fe are the micronutrients that accumulated in the highest quantities in Newhall navel orange fruit. The patterns of seasonal change in the concentrations of macro- and micronutrients for trifoliate orange-grafted and citrange-grafted navel orange trees were generally similar.

산수유(Corni Fructus)의 채취 시기에 따른 이화학적 품질 특성

To determine the proper picking period for Corni Fructus, the seed removal degree, free sugar contents, antioxidant capacities, and Hunter's color values were investigated at intervals of 15 days from 236 days after full bloom (DAFB) to 327 DAFB. The seed removal degree maximized at 280 DAFB (p&lt;0.05), at this point the moisture contents were 197.40% (db) and 66.00% (wb). The seed removal degrees were also investigated during hot air drying, and the best seed removal degree was obtained at moisture contents of 191.90% (db) and 65.74% (wb), similar to those observed at 280 DAFB. Fructose and glucose were detected, and their contents decreased slowly after 280 DAFB. Total phenolic contents (TPC), and DPPH radical scavening activity both decreased over the picking periods, but total anthocyanin contents (TAC) decreased after 280 DAFB. The redness, and yellowness of Corni Fructus powders, determined by using Hunter's colorimeter, decreased after 280 DAFB, but lightness decreased over the picking periods. Studies of the physicochemical quality characteristics revealed that the proper picking period of Corni Fructus should be 280 DAFB.

Post-bloom and preharvest treatment of ‘Braeburn’ apple trees with prohexadione-calcium and GA4+7 affects vegetative growth and postharvest incidence of calcium-related physiological disorders and decay in the fruit

Calcium (Ca) deficiency disorders in apple fruit have been associated with high gibberellins (GAs) activity in the tree. This study was carried out to assess the effects of treatments of ‘Braeburn’ apple trees with prohexadione-calcium (ProCa, an inhibitor of GAs biosynthesis) or gibberellins (GA4+7) on vegetative growth of the trees and postharvest incidence of Ca-related physiological disorders and decay in the fruit. ProCa (300 mg L-1) or GA4+7 (300 mg L-1) treatments were applied post-bloom (PB) and preharvest (PH). PB treatments started 15 days after full bloom (DAFB), with one application every week and six applications in total. PH treatments started five weeks before anticipated harvest (125 DAFB), with one application every week and four applications in total. Control trees were left untreated. When applied PB, ProCa reduced and GA4+7 promoted vegetative growth of the trees. ProCa PB delayed the impairment of xylem functionality (at the proximal region of the fruit) during fruit growth on the tree. Treatments had no effect on fruit weight, pectinmethylesterase (PME) activity or the expression of CAX3, CAX6 and V-ATPase (transporters of Ca into the vacuole) genes assessed in the external cortical tissue at the distal end of the fruit at harvest. When sprayed PB, ProCa increased the total Ca content and reduced K/Ca, Mg/Ca, N/Ca, (Mg + K)/Ca and (K + Mg + N)/Ca ratios in the flesh at the distal portion of the fruit, compared to the treatment with GA4+7, but without differing from the control. In general, ProCa application PB or PH reduced the expression of Ca-ATPase1, Ca-ATPase2, H+-PPase and CAX2 (Ca transporters into the vacuole) genes, increased total water‐soluble Ca and reduced electrolyte leakage in the fruit at harvest. After two months of cold storage followed by five days of shelf-life, the incidence and severity of bitter pit (BP) was lower on fruit from trees treated with ProCa PH, and higher on fruit from trees treated with GA4+7 PB. GA4+7 PB also increased the incidence of skin cracking and decay in the fruit. The results showed that ProCa application represents a feasible tool to reduce the incidence of BP. However, ProCa is more effective to reduce BP if applied weekly for five week before harvest.

Response of Fruit Bagging to Lignin Biosynthesis and Expression of Related Genes in Fruit Peel of Sand Pear (Pyrus pyrifolia Nakai) cv. Cuiguan

This study explored the effects of different colored bags (blue, green, white, yellow, orange, and red) on russet deposition on the peel of semi-russet ‘Cuiguan’ pears 10 days after full bloom (DAFB). The process of russeting of the peel and structure of the cork layer were characterized by microscopy and scanning electron microscopy (SEM), followed by the detection of lignin and the activity of enzymes involved in lignin synthesis. The expression of cinnamate-4-hydroxylase, 4-coumarate:coenzyme A ligase, cinnamyl alcohol dehydrogenase, cinnamoyl-CoA reductase, and peroxidase, which were related to phenylalanine ammonia-lyase, was determined via real-time quantitative polymerase chain reaction. Russeting of the outer peel of ‘Cuiguan’ pear accumulated rapidly at 80 DAFB, and a positive relationship between the russet index and lignin content was observed. Red and infrared (IR) ray, partial far-IR light (600–800 nm), and ultraviolet-A light (350–400 nm) promoted russeting in ‘Cuiguan’ pear peel, whereas green light decreased russeting, the russet index, enzymatic activities, and the expression levels of enzymes involved in lignin synthesis. Values of all these factors were higher for ‘Cuiguan’ pears in red bags than for those in bags of other colors. These findings suggested that spectral components affected the synthesis of lignin and the formation of fruit russet. Storage in green bags reduced russeting and improved fruit appearance.

Ripening quality of kiwifruit cultivars is affected by harvest time

In this study, green ‘Hayward’, gold ‘Haegeum’ and red ‘Hongyang’ kiwifruit cultivars were harvested at 160, 170 and 180 days after full bloom (DAFB) and treated with 100 μL kg−1 ethylene to investigate the ripening quality at 25 °C. Significant (p < 0.05) interaction effects between cultivars and harvest times on firmness and firmness related parameters, biochemical parameters, physiological parameters, and overall sensory quality were observed during the study. The results of our study revealed that the ripening quality of kiwifruit cultivars could be influenced by harvest time. During ripening, similar increasing trends were observed for sucrose, glucose, fructose, and total simple sugars until 4 d ripening and maintained or slightly reduced afterward, irrespective of cultivar and harvest time. In addition, based on firmness and firmness related parameters (respiration rate, ethylene production rate, pectins and polygalacturonase (PG) activity), eating quality was attained by gold ‘Haegeum’ and red ‘Hongyang’ on the 2nd day of ripening, whereas green ‘Hayward’ attained eating quality on the 4th day, irrespective of harvest time. However, based on the lowest weight loss to attain eating quality during ripening, which avoids the risk of shriveling, we suggest to harvest red ‘Hongyang’, gold ‘Haegeum’ and green ‘Hayward’ at 160, 170 and 170 DAFB, respectively. The shortest possible harvest time without compromising quality, as observed in this study, could also help growers to reduce production cost and it assists further distributions to consumers.

Investigation and analysis of relationship between mineral elements alteration and cork spot physiological disorder of Chinese pear ‘Chili’ (Pyrus bretschneideri Rehd.)

Cork spot is one of the most damaging physiological disorders in pear. However, the mechanism of cork spot is unclear. Ca2+ deficiency is considered as the major agent to cork spot. In this study, we investigated cork spot characteristics in Chinese ‘Chili’ (Pyrus bretschneideri Rehd.) and analyzed the relationship between mineral elements alteration and cork spot occurrence. We found early initiation of cork spot disorder in ‘Chili’ at 80 days after full bloom (DAFB). Cork spot in disordered fruit mostly distributed around the fruit eye with necrotic and brown tissues at the spotted site in flesh. At harvest time, cork spot disordered fruit had a smaller size, higher firmness, lower titratable acidity, higher lignin and cellulose content than healthy fruit, while starch concentration was the same between disordered and healthy fruit. Differences of mineral elements content were also found in both leaves and fruits, and Ca2+ distribution was visualized to be concentrated inside cell wall in disordered fruit cells. Principal components analysis (PCA) of mineral elements data showed that fruit samples could be separated according to their healthy or disordered condition at 80 and 160 DAFB. However, no significant correlation was found between cork spot disorder and mineral elements data. Ca2+ concentration was not suggested as the cork spot biochemical marker in our study. At last, we hypothesized the relationship between cork spot occurrence and Ca2+ distribution in ‘Chili’ and summarized the factors probably contributing to Ca2+ deficiency disorder, which would be useful in designing orchard strategies against cork spot.

Influence of the Period of Peach Tree Chemical Thinning on Fruit Quality

The need to decrease production costs along with the lack of man power in the countryside has asked for cultural practices which lead to these factors, such as thinning. Thus, chemical thinning has been studied as an alternative to fruit manual thinning. Therefore, this study aimed at evaluating the quality of peach tree fruits after chemical thinning with metamitron at different time periods in the south of Brazil. The experiment was carried out in a commercial peach tree orchard with cultivars &amp;lsquo;Maciel&amp;rsquo; in Morro Redondo, Rio Grande do Sul state, Brazil, from 2015 to 2016. Treatments consisted in the application of metamitron (doses of 200 mg L-1) on the 20th, 30th, 40th, 50th and 60th day after full bloom (DAFB) and manual thinning on the 40th DAFB. Epidermis color, pulp firmness, ripeness index, soluble solids, titratable acidity, juice pH, total phenolic compounds and antioxidant activity were evaluated. The application of metamitron in peach tree thinning did not affect peach color. Changes in the other variables related to the quality of fruits depended on the application period of metamitron in the thinning process and between crops.

Effect of Orchard Management Factors on Flesh Color of Two Red-Fleshed Apple Clones

Little is known about factors affecting anthocyanin biosynthesis in red-fleshed apples (Malus × domestica Borkh.). The objective was to establish the effects of orchard management factors on flesh anthocyanin content of dark-colored (DC) and light-colored (LC) apple clones. Flesh color was assessed by measuring color in the L, a, b mode using a spectrophotometer and predicting the anthocyanin content based on relationships between the absorption of a flesh extract at 530 nm and the L-value determined using a spectrophotometer (r2 = 0.99 ***). Fruit from the DC clone were red by 86 days after full bloom (DAFB), whereas the LC clone began to color at 136 DAFB. Color intensity in both clones decreased from the top of the tree to the base. Further, the intensity of the flesh color of the DC clone decreased with shading (94% absorption of incident photosynthetic active radiation). Covering a fruit with a UV absorbing film (100% UV absorption) had no effect on flesh color in the DC clone but decreased color in the LC clone. Fruit thinning increased color in DC and LC fruit. There was little change in flesh color during storage. However, the DC clone developed severe flesh browning as storage progressed beyond 30 days. The results demonstrated that light (visible and UV wavelength) stimulated, whereas shade inhibited, anthocyanin biosynthesis in the flesh under orchard conditions.

Harvest time affects quality and storability of kiwifruit (Actinidia spp.): Cultivars during long-term cool storage

In this study, the possibility of prolonging the freshness of kiwifruit cultivars for the purpose of even distribution in time and place has been investigated. Green ‘Hayward’, gold ‘Haegeum’ and red ‘Hongyang’ kiwifruit cultivars were harvested at 160, 170 and 180 days after full bloom (DAFB) and stored at 0 °C until 4 months. Firmness and firmness related parameters, biochemical parameters, physiological parameters, decay percentage and overall sensory evaluation were observed during the study. On the basis of harvesting time, the order of storability of all the three cultivars could be 160 DAFB > 170 DAFB >180 DAFB, respectively. The study revealed that kiwifruit harvested at 160 DAFB were stored up to 4 months without affecting major quality indices during storage. However, overall sensory quality evaluation showed that kiwifruits harvested at 160 DAFB attained good eating quality after 3 months of storage in green and red kiwi cultivars, and after one month storage in gold kiwi cultivar. Hence, in order to ensure good sensory quality and to fulfill consumer's preference during distribution, further ripening studies like exogenous ethylene treatment are necessary immediately after harvest or at any time during the storage period

Transcriptional regulation of abscisic acid biosynthesis and signal transduction, and anthocyanin biosynthesis in ‘Bluecrop’ highbush blueberry fruit during ripening

Highbush blueberry (Vaccinium corymbosum) fruit accumulate high levels of anthocyanins during ripening, which might be controlled by abscisic acid (ABA), a signal molecule in non-climacteric fruits. For an integrated view of the ripening process from ABA to anthocyanin biosynthesis, we analyzed the transcriptomes of ‘Bluecrop’ highbush blueberry fruit using RNA-Seq at three ripening stages, categorized based on fruit skin coloration: pale green at ca. 30 days after full bloom (DAFB), reddish purple at ca. 40 DAFB, and dark purple at ca. 50 DAFB. Mapping the trimmed reads against the reference sequences yielded 25,766 transcripts. Of these, 143 transcripts were annotated to encode five ABA biosynthesis enzymes, four ABA signal transduction regulators, four ABA-responsive transcription factors, and 12 anthocyanin biosynthesis enzymes. The analysis of differentially expressed genes between the ripening stages revealed that 11 transcripts, including those encoding nine-cis-epoxycarotenoid dioxygenase, SQUAMOSA-class MADS box transcription factor, and flavonoid 3′,5′-hydroxylase, were significantly up-regulated throughout the entire ripening stages. In fruit treated with 1 g L−1 ABA, at least nine transcripts of these 11 transcripts as well as one transcript encoding flavonoid 3′-hydroxylase were up-regulated, presumably promoting anthocyanin accumulation and fruit skin coloration. These results will provide fundamental information demonstrating that ABA biosynthesis and signal transduction, and anthocyanin biosynthesis are closely associated with anthocyanin accumulation and skin coloration in highbush blueberry fruit during ripening.

Differential expression of genes encoding phenylpropanoid enzymes in an apricot cultivar (Prunus armeniaca L.) with cleavable endocarp

Phenylpropanoid pathway related genes were identified and analyzed by co-expression network and expression pattern. NST1 may regulate the expression of CAD to affect the lignin deposition of ‘Liehe’ apricot endocarp. Apricot (Prunus Armeniaca L.) is a typical Rosaceae stone fruit tree. The extensive lignification of its endocarp is an important metabolic event during fruit ripening. There are abundant apricot germplasm resources in China, including a special apricot cultivar, ‘Liehe’ (LE), which has a thin, soft, cleavable endocarp with a hardness 45.84% that of the ‘Jinxihong’ (JG) apricot (with normal hardened-endocarp). To understand the molecular mechanisms behind the LE phenotype, differentially expressed genes (DEGs) encoding key enzymes involved in phenylpropanoid biosynthesis were mined from transcriptome data by the co-expression network and expression patterns. DEGs encoding key enzymes involved in phenylpropanoid biosynthesis were significantly down-regulated in LE, and the activity of these enzymes exhibited similar results. NST1 (NAC secondary wall thickening promoting factor 1) expression levels in LE were only 13.7%, 2.8%, 9.4%, and 82.5% that in JG at 9, 15, 21, and 30 days after full bloom (DAFB), respectively. CAD (Cinnamyl alcohol dehydrogenase) expression levels in LE were 1.3%, 0.7%, 0.2% and 2.7% that in JG at 15, 21, 30, 49 DAFB, respectively. CAD activity in LE was 46.4% and 63.6% that in JG at 42 and 49 DAFB, respectively. We thus used homologous cloning to determine the sequence differences of CAD and NST1 in LE and JG. Our results will help understand the molecular mechanisms underlying endocarp cleavage in LE apricot and provide a useful reference for further investigation of lignification during endocarp development. NST1 may regulate CAD which involved in the phenylpropanoid pathway and affect lignin deposition in LE endocarp.

Transcriptomic and Gas Chromatography-Mass Spectrometry Metabolomic Profiling Analysis of the Epidermis Provides Insights into Cuticular Wax Regulation in Developing 'Yuluxiang' Pear Fruit.

The layer of cuticular wax covering fruits plays important roles in protecting against disease, preventing non-stomatal water loss, and extending shelf life. However, the molecular basis of cuticular wax biosynthesis in pear (Pyrus) fruits remains elusive. Our study thoroughly investigates cuticular wax biosynthesis during pear fruit development from morphologic, transcriptomic, and gas chromatography-mass spectrometry metabolomic perspectives. Our results showed that cuticular wax concentrations increased during the early stage [20-80 days after full bloom (DAFB)] from 0.64 mg/cm2 (50 DAFB) to 1.75 mg/cm2 (80 DAFB) and then slightly decreased to 1.22 mg/cm2 during the fruit ripening period (80-140 DAFB). Scanning electron microscopy imaging indicated that wax plate crystals increased and wax structures varied during the pear fruit development. The combined transcriptomic and metabolomic profiling analysis revealed 27 genes, including 12 genes encoding transcription factors and a new structural gene (Pbr028523) encoding β-amyrin synthase, participating in the biosynthesis, transport, and regulation of cuticular wax according to their expression patterns in pear fruit. The quantitative real-time polymerase chain reaction experiments of 18 differentially expressed genes were performed and confirmed the accuracy of the RNA-Seq-derived transcript expression. A model of VLCFAs and cuticular wax synthesis and transport in pear fruit is proposed, providing a mechanistic framework for understanding cuticular wax biosynthesis in pear fruit. These results and data sets provide a foundation for the molecular events related to cuticular wax in 'Yuluxiang' pear fruit and may also help guide the functional analyses of candidate genes important for improving the cuticular wax of pear fruit in the future.

생육단계별 이화학 특성변화에 근거한 ‘한아름’ 배의 적숙기 판정

This study was conducted to determine the optimal physiological ripening time and suggest a reasonable harvest time indicator by analyzing the relationship between change in physicochemical characteristics and the sugar composition change patterns during development of 'Hanareum' fruit from 54 days after full bloom (DAFB) to 130 DAFB. The weight of fruits from 96 to 115 DAFB rapidly increased and then became gentle showing a typical sigmoidal curve. Flesh hardness decreased steadily after 96 DAFB; there was no significant difference in flesh hardness for 115, 125 and 130 DAFB fruits. The starch content began to reduce around the core for 119 DAFB. Moreover, sucrose and fructose contents started to increase with fruit development; however, the sucrose content continuously increased, whereas the fructose content started to decrease for 110 DAFB. Fruits of 125 and 130 DAFB did not show coloration according to the iodine test. Based on these results, it was estimated that the optimal physiological ripening time of 'Hanareum' was between 119 and 125 DAFB. The results of correlation analysis between fruit development change and sugar composition change patterns of fruits of 'Hanareum' showed that there was a strong linear relationship. Correlation coefficient between the sucrose/fructose (S/F) ratio and flesh hardness is -0.57, between S/F ratio and iodine test results is 0.80. Namely, S/F ratio is possible to use for harvest time determination indicator and the point of S/F ratio of 0.9–1.1 was considered to be ideal for the determination of the optimal physiological ripening time at which starch completely degrades.

Relationship of the bulk optical properties in 950–1650 nm wavelength range with internal quality and microstructure of kiwifruit during maturation

Investigating the relationship between bulk optical properties and internal quality/microstructure of kiwifruit during maturation is helpful to understand the evolution mechanisms of physiological properties. In this study, absorption coefficient (μa) and reduced scattering coefficient (μ′s) of kiwifruits during maturation, from 44 days after full bloom (DAFB) to 114 DAFB, were obtained using a single integrating sphere and inverse adding-doubling technique over the wavelength range of 950–1650 nm. Relationships of μa and μ′s with internal quality (i.e., soluble solids content (SSC), moisture content (MC) and firmness (FI)) and microstructural parameters (i.e., area and diameter of cells) were investigated. The results showed that the strongest correlations between μa and SSC and MC were observed around the μa peak of 1390 nm, with correlation coefficients (R) of −0.80 and 0.88, respectively. Over the whole wavelength range, the μ′s had stronger correlation with FI (|R| = 0.74–0.87) than with SSC (|R| = 0.49–0.81) and MC (|R| = 0.59–0.80). The areas and diameters of large and small cells of kiwifruit tissue were highly correlated with the μ′s over the whole wavelength range with R of 0.65–0.91. This study suggests that the bulk optical properties could be used to evaluate the internal quality and microstructure of kiwifruits during maturation.

Proteomic analysis of the key mechanism of exocarp russet pigmentation of semi-russet pear under rainwater condition

This study aimed to explore the mechanism of exocarp russet pigmentation of semi-russet ‘Cuiguan’ sand pears at the proteome level following rainwater. Exocarp russeting was characterized in semi-russet sand pears cultivated in the rain shelter and control (rainwater) groups via microscopy and ultra-microscope observations, followed by determination of lignin content and enzyme activities. The differentially expressed proteins between different cultivation conditions were analyzed using the isobaric tags for relative or absolute quantitation (iTRAQ) technology, followed by confirmation by real-time quantitative polymerase chain reaction (qPCR). The rust color of the outer pericarp of ‘cuiguan’ was rapidly accumulated on 60–80 days after full bloom (DAFB) in both two groups. Under the shelter condition, most stratum corneum cracks were shallow and had less suberization. The lignin content as well as the enzyme activities of phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD), catechol-O-methyltransferase (COMT), cinnamoyl-CoA reductase (CCR) and peroxidase (POD) in exocarp from the rain shelter group were all lower than that in control group. Additionally, 309 differentially expressed proteins were identified in the rain shelter group, and eight down-regulated proteins associated with lignin monomer synthesis were identified, such as PAL (E9JWF1), CCR1 (F4Y9E7), CAD (U3PGC0), two peroxidases (K9URQ0 and M5W3Y0, respectively), two COMT (S5TPC3 and Q09K02, respectively) and omega-hydroxypalmitate O-feruloyl transferase (HHT1) (M5VMR7), and their expression was confirmed by qPCR. Moreover, many defense proteins were significantly down-regulated. These findings suggest that the rain shelter treatment may affect phenylalanine lignin monomer synthesis and subsequent defense metabolism by regulating corresponding proteins, thus decreasing exocarp russet accumulation in semi-russet pear. This study provides a further understanding of pear russeting and plant defense mechanisms.

The influence of fruit thinning on fruit drop and quality of citrus

This experiment aims to know the effects of fruit thinning on fruit drop and fruit quality of citrus. The research was conducted in a citrus orchard in Purbalingga, Central Java, Indonesia in 2016/2017 and 2017/2018. There were nine observed ways of fruit thinning namely 15 days after full bloom (DAFB) by maintaining one fruit per branch, two fruits per branch, three fruits per branch, at 30 DAFB by maintaining one fruit per branch, two fruits per branch, three fruits per branch, at 45 DAFB by maintaining one fruit per branch, two fruits per branch, and three fruits per branch. The result showed that fruit thinning did not influence to the quality of citrus fruits (diameter and weight of fruits, vitamin C and sugar content, total acid, and soluble solids). The lowest fruit drop per branch was showed at thinning at 45 DAFB by maintaining one fruit per branch, whereas the lowest fruit drop per tree was achieved by fruit thinning at 45 DAFB by maintaining two fruits per branch.

Foliar applications of calcium do not impact on fruit and leaf nutrient concentration or quality of ‘O’Neal’ blueberry

ABSTRACTCalcium (Ca) has been considered a key element in maintaining fruit quality and extending the storage period of several fruits. The main blueberry (interspecific hybrids of Vaccinium corymbosum x V. darrowii) market for the Southern Hemisphere production involves a long transport between harvest and consumption. Foliar Ca sprays during the pre-harvest constitutes a common practice for improving Ca concentration [Ca] in fruits and therefore in alleviating the loss of firmness, dehydration and rot decay during postharvest. In this study, two formulations of Ca; Ca-nitrate [Ca(NO3)2] and chelate Ca-oxide (Ca-gluconate; Ca-Glu) were sprayed four times during pre-harvest of blueberry cv. O’Neal. [Ca] in the fruits was followed after each application and fruit quality parameters were determined at harvest and during 28 days of cold storage. Both formulations were ineffective in increasing [Ca] in the berries (or leaves) after any of the four applications. In fruits, [Ca] decreased from 0.32% at 25 days after full bloom (DAFB) to 0.11% Ca at harvest time. Other minerals such as magnesium (Mg), potassium (K), or nitrogen (N) remained unaffected by the treatments. Data shows that foliar pre-harvest applications of Ca, regardless of formula, were ineffective at increasing [Ca] or improving the quality of the fruit.

Histological and proteomic approaches to study floral bud induction in relation to biennial bearing in apple

Biennial or alternate bearing in fruit trees leads to fluctuating yields, characterized by ‘On’ years with high crop loads followed by ‘Off’ years with little or no yield. To study the mechanism of biennial bearing in apple (Malus domestica Borkh.), the cultivars ‘Royal Gala’ as a regular bearer and ‘Fuji’ as a strongly alternating cultivar were investigated. ‘Off’ trees were completely thinned at full bloom, whereas ‘On’ trees were not thinned to maintain the natural high crop load. The first signs of floral bud initiation were detected for ‘Fuji’ at 70 days after full bloom (DAFB) and 120 DAFB for ‘Off’ and ‘On’ trees, respectively. In ‘Royal Gala’, initiated buds were observed not before 100 DAFB in both treatments. Hence, buds from ‘Fuji’ ‘Off’ trees committed to flowering about one month earlier than those from ‘Royal Gala’ ‘Off’ trees. In contrast, flower initiation of buds from ‘Royal Gala’ ‘On’ trees occurred 20 days earlier when compared to those from ‘Fuji’ ‘On’ trees. Electrospray ionization mass spectrometry (ESI-MS) coupled with ultra-high performance liquid chromatography (UHPLC) allowed the identification of 3011 proteins. A Student’s T-Test revealed 181 differentially expressed proteins between buds from ‘On’ and ‘Off’ trees. Specifically, 81 proteins were significantly upregulated in floral buds and 100 proteins in vegetative buds, respectively. The largest log2 fold change of 3.17 was identified for a zinc metalloprotease in buds from the ‘Fuji’ ‘On’ treatment. The protein with the highest up-regulation in ‘Fuji’ ‘Off’ buds was a nigrin b-like protein. Histological analysis of bud development has proven to be an essential and reliable tool to identify the time point of floral initiation in apple. Moreover, this study demonstrates that especially in biennial bearing cultivars, crop load heavily influences the onset of floral bud initiation and can differ for up to 50 days within the same cultivar depending on crop load. The identification of this critical period enables in-depth analysis of biochemical changes such as differences in protein profiles to further reveal the mechanism of biennial bearing in apple.

Elaboration and Characterization of Active Apple Starch Films Incorporated with Ellagic Acid

Apple starch films were obtained from apples harvested at 60, 70, 80 and 90 days after full bloom (DAFB). Mechanical properties and water vapor permeability (WVP) were evaluated. The apple starch films at 70 DAFB presented higher values in the variables of tensile strength (8.12 MPa), elastic modulus (3.10 MPa) and lower values of water vapor permeability (6.77 × 10−11 g m−1 s−1 Pa−1) than apple starch films from apples harvested at 60, 80 and 90 DAFB. Therefore, these films were chosen to continue the study incorporating ellagic acid (EA). The EA was added at three concentrations [0.02% (FILM-EA0.02%), 0.05% (FILM-EA0.05%) and 0.1% (FILM-EA0.1%) w/w] and compared with the apple starch films without EA (FILM-Control). The films were characterized by their physicochemical, optical, morphological and mechanical properties. Their thermal stability and antioxidant capacity were also evaluated. The FILM-Control and FILM-EA0.02% showed a uniform surface, while FILM-EA0.05% and FILM-EA0.1% showed a rough surface and insoluble EA particles. Compared to FILM-Control, EA modified the values of tensile strength, elasticity modulus and elongation at break. The antioxidant capacity increased as EA concentration did. EA incorporation allowed obtaining films with higher antioxidant capacity, capable of blocking UV light with better mechanical properties than film without EA.

Expression of genes in the potential regulatory pathways controlling alternate bearing in ‘Fuji’ (Malus domestica Borkh.) apple trees during flower induction

Most perennial fruit trees have an alternate bearing problem where a heavy fruit load is produced one year (ON year) but few flowers and fruits produced the next year (OFF year), resulting in a significant fluctuation in production. In the present study, comparative transcriptome analysis of terminal buds of apple (Malus domestica Borkh., cv. Nagafu No. 2) trees was conducted during the floral induction period in the ON and OFF years to identify the potential regulatory pathways controlling alternate bearing. A total of 1027 differentially expressed genes (DEGs), most of which were involved in secondary metabolism, sugar metabolism, plant hormone pathways, were identified. The analysis focused on differences in sugar content and hormone levels between the ON and OFF trees. Sucrose content, zeatin-riboside (ZR), and abscisic acid (ABA) levels were lower in ON-year buds than in OFF-year buds. ON buds also had elevated levels of gibberellins (GAs), with a higher expression of GA20 oxidase (GA20ox) and a significant lower level of RGA-like2 (RGL2). Expression analyses also revealed a significantly higher level of SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE genes (MdSPL1, MdSPL6 and MdSPL12) transcripts levels in buds of OFF trees at 45 days after full bloom (DAFB). LEAFY (LFY) expression increased significantly prior to flower induction in OFF buds. These findings provide new information of the role of hormones in alternate bearing, as well as other processes, and provide new insights into the molecular mechanisms regulating alternate bearing in perennial fruit trees.