Days After Full Bloom Research Articles

Phenolic Content and Antioxidant Activity during the Development of 'Brookfield' and 'Mishima' Apples.

The aim of this study was to characterize the changes in the contents of total (TPC) and individual (IPC) phenolic compounds, the total antioxidant activity (TAA) in the peel and pulp, and total anthocyanins (TAN) in the peel during the development of the fruits of 'Brookfield' and 'Mishima' apple trees. 'Brookfield' apples were harvested from the 49th to the 138th days after full bloom (DAFB) and 'Mishima' apples from the 45th to the 172th DAFB. In the pulp, the IPC, TPC, and TAA rapidly reduced at 75 and 79 DAFB for the 'Brookfield' and 'Mishima' apples, respectively, and then remained constant until commercial maturity. In the peel of 'Brookfield' apples there was a reduction in the TPC and TAA at 79 DAFB. The quercetin 3-galactoside, epicatechin, and procyanidin B2 contents reduced up to 107 DAFB with a subsequent increase in the values at commercial maturity. In the peel of 'Mishima' apples there was a reduction in the TPC, TAA, epicatechin, and procyanidin B1 and B2 contents at 130 DAFB, with a subsequent increase until commercial maturity. The TAN content in the peel increased during the 2 and 4 weeks prior to commercial maturity for 'Brookfield' and 'Mishima' apples, respectively. In the pulp and peel of both cultivars there was a reduction in the IPC, TPC, and TAA as the development proceeded. On nearing commercial maturity, there was an increase in the contents of quercetin 3-galactoside, epicatechin, procyanidin B2, and TAN in the peel for both cultivars.

Berry Abscission in Vitis vinifera L. cv. Waltham Cross: Changes in Abscission-related Factors during Berry Development

During the 1999 season, changes in total soluble solids (TSS), titratable acids (TA), pedicel diameter, berry diameter, berry mass and fruit removal force (FRF) were determined at biweekly intervals from 27 until 111 days after full bloom (DAFB) for Waltham Cross table grapes. In addition, at each assessment stage, grape bunches were detached and held in the dark at about 25°C for 80 h. Thereafter, moisture loss, FRF, berry abscission potential as well as percentage berry abscission were determined. During stages I and II of fruit growth (27 to 54 DAFB), TSS did not change significantly, while TA increased. FRF increased significantly during this early stage of berry development, indicating a strengthening of the abscission zone tissue. During stage III (after 54 DAFB), a decline in FRF occurred, which coincided with a perceptible increase in TSS and a decrease in TA. Berry mass increased significantly from 27 to 111 DAFB. Pedicel diameter only increased significantly for the period 27 to 41 DAFB, while berry diameter increased significantly for the period 27 to 97 DAFB. Grapes sampled at 27 DAFB had a significantly lower FRF and significantly higher levels of berry abscission and moisture loss after the 80-hour period in the dark, compared with grapes sampled at a later stage. At 27 DAFB, the abscission zone developed between the pedicel and the rachis, thereafter it developed between the pedicel and the berry. Although FRF did not change significantly as berries ripened (from 83 to 111 DAFB), abscission potential and percentage berry abscission were significantly higher for grapes harvested at 83 DAFB at a TSS of 12.3°Brix than for grapes harvested more mature, at a higher TSS. Moisture loss correlated significantly (P<0.0001) with berry abscission, with a correlation coefficient of 0.84. Berry abscission also correlated significantly (P<0.0001) with abscission potential, pedicel and berry diameter, FRF (at sampling), FRF (after 80 h) and berry mass, but not with TSS or TA.

Influence of Mineral Fertilizer, Farmyard Manure, Natural Zeolite, and their Mixture on Fruit Quality and Leaf Micronutrient Levels of Apple Trees

ABSTRACTAdequate soil conditions and fertilization as a cultural practice are the basis of fruit crops production. This study was conducted in 2011 and 2012 to determine impact of soil application of complex nitrogen, phosphorus, and potassium (NPK) mineral fertilizer alone and its mixture with cattle manure (M) and natural zeolite (A) on yield, fruit physico-chemical traits and leaf micronutrient amounts at 120 days after full bloom (DAFB) in “Idared” and “Melrose apples grown on heavy and acidic soil under Serbian conditions. Results showed that NPK increased yield in “Idared” and both NPK+A and NPK+M in “Melrose.” Fertilizer applications were not influenced by fruit physico-chemical attributes, but differences between cultivars were significant. Fertilizers induced changes of leaf micronutrients amount, but effect was not consistent. In “Idared,” NPK+A and NPK+M mixtures improved amounts of the most micronutrients, whereas in “Melrose,” NPK and mixture NPK+A+M increased leaf micronutrients in more cases. According to deviation from optimum percentage (DOP and ΣDOP indexes), excessive leaf iron (Fe) and zinc (Zn) was found and deficiency of manganese (Mn), copper (Cu), and boron (B). “Melrose” exhibited much better balanced nutritional values for nutrients as compared to “Idared,” whereas NPK+M in “Idared” and NPK alone in “Melrose” promoted better balanced nutritional values. Since the impact of nutrients on the studied features is not consistent, more research will need to be conducted to investigate the long-term effect of NPK alone or in mixture with natural zeolite and manure fertilization on apples.

Non-Destructive Evaluation of the Leaf Nitrogen Concentration by In-Field Visible/Near-Infrared Spectroscopy in Pear Orchards.

Non-destructive and timely determination of leaf nitrogen (N) concentration is urgently needed for N management in pear orchards. A two-year field experiment was conducted in a commercial pear orchard with five N application rates: 0 (N0), 165 (N1), 330 (N2), 660 (N3), and 990 (N4) kg·N·ha−1. The mid-portion leaves on the year’s shoot were selected for the spectral measurement first and then N concentration determination in the laboratory at 50 and 80 days after full bloom (DAB). Three methods of in-field spectral measurement (25° bare fibre under solar conditions, black background attached to plant probe, and white background attached to plant probe) were compared. We also investigated the modelling performances of four chemometric techniques (principal components regression, PCR; partial least squares regression, PLSR; stepwise multiple linear regression, SMLR; and back propagation neural network, BPNN) and three vegetation indices (difference spectral index, normalized difference spectral index, and ratio spectral index). Due to the low correlation of reflectance obtained by the 25° field of view method, all of the modelling was performed on two spectral datasets—both acquired by a plant probe. Results showed that the best modelling and prediction accuracy were found in the model established by PLSR and spectra measured with a black background. The randomly-separated subsets of calibration (n = 1000) and validation (n = 420) of this model resulted in high R2 values of 0.86 and 0.85, respectively, as well as a low mean relative error (<6%). Furthermore, a higher coefficient of determination between the leaf N concentration and fruit yield was found at 50 DAB samplings in both 2015 (R2 = 0.77) and 2014 (R2 = 0.59). Thus, the leaf N concentration was suggested to be determined at 50 DAB by visible/near-infrared spectroscopy and the threshold should be 24–27 g/kg.

The von Bertalanffy growth model for horticulture: predicting tomato size at harvest

Traditionally, crop load and fruit yield from previous seasons are used as indicators for prediction of fruit size. Disregarding the inevitable biological variation between fruit, von Bertalanffy (1938) described the growth, expressed as length, of virtually any living organism. The model is here extended to include the variation between individuals in a batch. Using this extended model, fruit size and its variation can be predicted, using measurements of a large number of fruit at a single point during early development. The diameter of 200 tomatoes was measured 15 days after full bloom (DAFB). Using the density function derived from the extended von Bertalanffy model, and applying prior knowledge of some of the model parameters, the variation in size at harvest could be predicted. Validation of the results was obtained by comparing the predicted sizes with the diameters of the same tomatoes at harvest.

Effects of postharvest methyl jasmonate treatment on aromatic volatile biosynthesis by ‘Nanguoli’ fruit at different harvest maturity stages

ABSTRACTThe ripe fruit of Pyrus ussuriensis ‘Nanguoli’ is favoured by people for its attractive colour, exquisite flesh and pleasant flavour. However, its flavour is negatively affected by early harvest. Therefore, this study aimed to determine whether exogenous methyl jasmonate (MJ) can help to regulate aromatic volatiles biosynthesis in pre-climacteric ‘Nanguoli’ fruit at different maturity stages (135 days after full bloom (DAFB) or ‘early harvested’ and 145 DAFB or ‘normal harvested’). MJ promoted aromatic volatile biosynthesis in normal harvested fruit, with the number of volatile compounds increasing from 43 in untreated fruit to 51 and 57 in fruit that had been treated with 1 and 5 mM MJ, respectively. By contrast, MJ had little effect on early harvested fruit, which exhibited an increase from 41 to 49 and 44 volatile compounds following treatment with 1 and 5 mM MJ, respectively. The total content of aromatic volatiles also increased by 53.75% and 66.82% in normal harvested fruit treated with 1 an...

Effects of postharvest methyl jasmonate treatment on aromatic volatile biosynthesis by ‘Nanguoli’ fruit at different harvest maturity stages

ABSTRACTThe ripe fruit of Pyrus ussuriensis ‘Nanguoli’ is favoured by people for its attractive colour, exquisite flesh and pleasant flavour. However, its flavour is negatively affected by early harvest. Therefore, this study aimed to determine whether exogenous methyl jasmonate (MJ) can help to regulate aromatic volatiles biosynthesis in pre-climacteric ‘Nanguoli’ fruit at different maturity stages (135 days after full bloom (DAFB) or ‘early harvested’ and 145 DAFB or ‘normal harvested’). MJ promoted aromatic volatile biosynthesis in normal harvested fruit, with the number of volatile compounds increasing from 43 in untreated fruit to 51 and 57 in fruit that had been treated with 1 and 5 mM MJ, respectively. By contrast, MJ had little effect on early harvested fruit, which exhibited an increase from 41 to 49 and 44 volatile compounds following treatment with 1 and 5 mM MJ, respectively. The total content of aromatic volatiles also increased by 53.75% and 66.82% in normal harvested fruit treated with 1 and 5 mM MJ, respectively, whereas early harvested fruit exhibited only slight increases. There was no significant difference between the effects of 1 and 5 mM MJ on aromatic volatile biosynthesis, indicating that the observed effects were dependent on the maturity stage of the fruit rather than the exogenous MJ concentration within the range tested. The ethylene production rate exhibited similar changes to those observed for the aromatic volatile content and there were no significant differences in the aromatic volatile contents of ‘Nanguoli’ fruits that had been treated with 1-methylcyclopropene (1-MCP) + MJ at different maturity stages. Therefore, it is deduced that ethylene may trigger aromatic volatile biosynthesis.

Effect of thinning time and fruit spacing on fruit maturity, yield, size, peel colour and quality attributes of peach cv. Flordasun

In present study 12-year-old Flordasun peach trees were manual thinned at 10, 15 and 20 cm spacings along the shoot on whole tree canopy at an interval of 0, 10, 20, 30 and 40 days after full bloom (DAFB) to know the effect of thinning time and fruit spacing on fruit maturity, yield, fruit size, peel colour and quality attributes over two growing seasons. Earliest fruit maturity was recorded in thinning at 20 DAFB (67 days) compared to control (77 days) and linear increase in fruit spacing recorded delay in days to fruit maturity. The thinning treatments decreased the yield significantly, while and least reduction was attributed at 20 DAFB (28.82 kg/tree). The fruits thinned at 20 DAFB and spaced at 20 cm recorded enhanced fruit weight (58.09 g), fruit length and diameter (4.79 and 4.56 cm) followed by 30 DAFB with spaced at 20 cm. The fruit skin colour (L*, a * and b*) value, improved in different thinning treatments, however, fruit thinned at 20 DAFB and spaced at 20 cm followed by 15 cm were found more effective. In fruit quality, highest TSS (12.10°B); TSS: acid ratio (20.17), ascorbic acid 6.52 mg/100 g) and lowest titratable acidity (0.60%) were recorded in fruits thinned at 20 DAFS and spaced at 20 cm followed by 15 cm with maximum total sugars (6.22%) content. The best results were dedicated to thinning of Flordasun peach at 20 DAFB with fruits spaced 20 to 15 cm apart.

Assesment of the total antioxidant capacity of apples peels during phisiological falls

The antioxidant capacity of apples peel extracts during the fruit development from three apple varieties (i.e., Ionathan, Golden Delicious and Starkrimson) were analyzed at 7, 15, 35, 65, 107, 145 days after full bloom (DAFB). The total antioxidant capacities of extracts were evaluated using free radical scavenging effect over 1,1-diphenyl l-2-picrylhydrazyl (DPPH) radical, being determined by a spectrophotometric method.The maximum antioxidant capacity was recorded in the apples harvested 7 DAFB.

Changes in anthocyanidin and anthocyanin pigments in highbush blueberry (Vaccinium corymbosum cv. Bluecrop) fruits during ripening

We monitored accumulation in terms of different types of anthocyanidin, in association with fruit skin coloration, in ‘Bluecrop’ highbush blueberry (Vaccinium corymbosum L.) at three stages of ripening: pale green, ca. 30 days after full bloom (DAFB); reddish purple, ca. 40 DAFB; and dark purple, ca. 50 DAFB. Total anthocyanin contents increased during ripening, while fruit skin color steadily became darker and bluer, as reflected in decreasing L* (a color space coordinate describing lightness) and b* (describing blue-yellow coloration). Of the six anthocyanidins commonly found in fruits, pelargonidin was absent throughout the ripening process. Cyanidin was first detected at the pale green stage. Peonidin, delphinidin, petunidin, and malvidin were first detected after fruits had passed through the reddish purple stage. The contents of delphinidin and malvidin increased more rapidly than those of other anthocyanidins, and were closely correlated with changes in fruit skin color, demonstrating that the types and quantities of anthocyanidins, which in turn form anthocyanins, were major determinants of fruit skin coloration. Four anthocyanins were detected at the reddish purple stage, and 22 were identified at the dark purple stage. All anthocyanins detected were glycosylated with glucose, galactose, or arabinose.

Diffuse Flesh Browning in ‘Honeycrisp’ Apple Fruit is Associated with Low Temperatures during Fruit Growth

Multiple types of flesh browning can occur as storage disorders in ‘Honeycrisp’ apple (Malus ×domestica Borkh.) fruit. Predicting its occurrence is hindered by differing definitions of the types of browning, incomplete understanding of their etiologies, and difficulty in assessing harvest maturity of ‘Honeycrisp’ fruit. In 2013, of ‘Honeycrisp’ fruit grown, harvested over multiple weeks, and stored in Maine, Minnesota, Ontario, and Quebec, only the Quebec fruit developed diffuse flesh browning. A detailed comparison showed that the Quebec fruit differed in size, but not in other quality attributes, from fruit of the other locations. The Quebec fruit experienced lower temperatures during active fruit growth and were increasing in cell size up to harvest. Analyses of climate data from 2009 to 2015 indicated that accumulated growing degree-days (GDD) 50–60 day after full bloom (DAFB) could account for 31% of the variation in diffuse flesh browning, and seasonal GDD &lt;500 are associated with a greater likelihood of injury. Fruit that exhibited diffuse flesh browning had higher magnesium and lower fructose levels than unaffected fruit. As these measurements were made after browning was assessed, the timing of the onset of these characteristics in relation to browning cannot be determined.

Comparative transcriptome analysis reveals a global insight into molecular processes regulating citrate accumulation in sweet orange (Citrus sinensis).

Citrate, the predominant organic acid in citrus, determines the taste of these fruits. However, little is known about the synergic molecular processes regulating citrate accumulation. Using 'Dahongtiancheng' (Citrus sinensis) and 'Bingtangcheng' (C. sinensis) with significant difference in citrate, the objectives of this study were to understand the global mechanisms of high-citrate accumulation in sweet orange. 'Dahongtiancheng' and 'Bingtangcheng' exhibit significantly different patterns in citrate accumulation throughout fruit development, with the largest differences observed at 50-70 days after full bloom (DAFB). Comparative transcriptome profiling was performed for the endocarps of both cultivars at 50 and 70 DAFB. Over 34.5 million clean reads per library were successfully mapped to the reference database and 670-2630 differentially expressed genes (DEGs) were found in four libraries. Among the genes, five transcription factors were ascertained to be the candidates regulating citrate accumulation. Functional assignments of the DEGs indicated that photosynthesis, the citrate cycle and amino acid metabolism were significantly altered in 'Dahongtiancheng'. Physiological and molecular analyses suggested that high photosynthetic efficiency and partial impairment of citrate catabolism were crucial for the high-citrate trait, and amino acid biosynthesis was one of the important directions for citrate flux. The results reveal a global insight into the gene expression changes in a high-citrate compared with a low-citrate sweet orange. High accumulating efficiency and impaired degradation of citrate may be associated with the high-citrate trait of 'Dahongtiancheng'. Findings in this study increase understanding of the molecular processes regulating citrate accumulation in sweet orange.

Differences in fruit growth and ripening of early-, mid- and late-season maturing Japanese plum cultivars

Introduction. Plum cultivars exhibit differences in their fruit quality; however, very little is known about the changes in fruit growth and quality of plum cultivars maturing in different seasons. This study was conducted to contribute to a better understanding of the fruit growth and ripening behavior of Japanese plum (Prunus silicina Lindl.) varieties according to their maturing season. Materials and methods. Three Japanese plum cultivars were studied: early- [‘Black Amber’ (BA)], mid- [‘Amber Jewel’ (AJ)] and late-season [‘Angelino’ (AG)] maturing. The increase in fruit weight and diameter was determined from days after full bloom (DAFB) to harvest, whilst changes in fruit pulp, skin and seed dry weights, fruit firmness, soluble solid contents (SSC), and titratable acidity (TA) were studied during days after stone hardening (DASH). Ethylene production, respiration rate, activities of 1-aminocyclopropane-1-carboxylic acid synthase (ACS) and 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) enzymes, fruit firmness, fruit color, SSC, TA, ascorbic acid, total antioxidant and carotenoid contents were determined at alternate days during fruit ripening. Results and discussion. All plum cultivars exhibited three distinct phases of fruit growth and development in the DAFB. The AG fruit exhibited the longest duration of phase-III, about 64 days and 12 days more, as compared with BA and AJ fruits, respectively. Fruit skin dry weight (%) was higher for AG fruit, whilst, AJ and BA fruits exhibited the highest increase in seed and pulp dry weight (%) during DASH. The BA and AJ fruits showed climacteric fruit ripening with a sharp rise in ACS and ACO enzymes; whereas AG fruit showed suppressed climacteric ripening. During the fruit ripening period AG fruit remained more firm with higher SSC, and SCC:TA ratio as compared with BA and AJ fruits. The level of ascorbic acid (24.8 mg 100 g-1 ) was higher in AG fruit. Whilst, total carotenoids (0.66 mg 100 g-1 ) and total antioxidants (215 ¯mol Trolox 100 g-1 ) were higher in AJ and BA fruit respectively. Conclusion. The physico-chemical changes during fruit ripening vary with cultivar and are associated with the level of endogenous ethylene production. Japanese plum cultivars exhibit varying levels of SSC, SSC:TA ratio, levels of individual and total antioxidants of their ripe fruits.

Gene Cloning, Expression and Enzyme Activity of Vitis vinifera Vacuolar Processing Enzymes (VvVPEs).

Vacuolar processing enzymes (VPEs) have received considerable attention due to their caspase-1-like activity and ability to regulate programmed cell death (PCD), which plays an essential role in the development of stenospermocarpic seedless grapes ovules. To characterize VPEs and the relationship between stenospermocarpic grapes and the VPE gene family, we identified 3 Vitis vinifera VPE genes (VvβVPE, VvγVPE, and VvδVPE) from the PN40024 grape genome and cloned the full-length complementary DNAs (cDNAs) from the ‘Vitis vinifera cv. Pinot Noir’ and ‘Vitis vinifera cv. Thompson Seedless’ varietals. Each of the VPEs contained a typical catalytic dyad [His (177), Cys (219)] and substrate binding pocket [Arg (112), Arg (389), Ser (395)], except that Ser (395) in the VvγVPE protein sequence was replaced with alanine. Phylogenetic analysis of 4 Arabidopsis thaliana and 6 Vitis vinifera VPEs revealed that the 10 VPEs form 3 major branches. Furthermore, the 6 grapevine VPEs share a similar gene structure, with 9 exons and 8 introns. The 6 grapevine VPEs are located on 3 different chromosomes. We also tested the enzymatic activity of recombinant VPEs expressed in the Pichia Pastoris expression system and found that the VvVPEs exhibit cysteine peptidase activity. Tissue-specific expression analysis showed that VvδVPE is only expressed in flowers, buds and ovules, that VvγVPE is expressed in various tissues, and that VvβVPE was expressed in roots, flowers, buds and ovules. The results of quantitative real-time PCR (qRT-PCR) suggested that VvβVPE in seeded grapes increased significantly at 30 days after full-bloom (DAF), close to the timing of endosperm abortion at 32 DAF. These results suggested that VvβVPE is related to ovule abortion in seedless grapes. Our experiments provide a new perspective for understanding the mechanism of stenospermocarpic seedlessness and represent a useful reference for the further study of VPEs.

Anthocyanin concentration and antioxidant activity in light-emitting diode (LED)-treated apples in a greenhouse environmental control system

Introduction. Anthocyanins are a group of flavonoids, and their synthesis is influenced by external and internal factors such as light, temperature, phytohormones and sugar concentration. A high anthocyanin concentration, which is related to redder coloration, is one of the factors of high-quality fruit. The effects of LED irradiation on the anthocyanin concentration and enzymatic and antioxidant activities in apple skin were studied. Materials and methods. Nine 8-year-old ‘Tsugaru’ apple trees (Malus domestica Borkh.) grafted onto Malling26 (M.26 EMLA) rootstocks planted in 45-L plastic pots covered with polyvinyl film (90% transmittance) and grown in a greenhouse were used. The effects of red or blue light-emitting diode (LED) irradiation on anthocyanin accumulation, the expression of MdMYB10 and UDP-glucose-flavonoid 3-O -glucosyltransferase (MdUFGT ) and superoxide anion radical (O scavenging activity in the skin of ‘Tsugaru’ apples were investigated under early heating cultivation in a greenhouse. Results and discussion. The anthocyanin concentrations in red LEDtreated apples were increased compared with those of the blue LEDtreated apples and the untreated control at 130 days after full bloom (DAFB). The relative expression of MdMYB10 and MdUFGT genes at 130 DAFB was also highest in the skin of apples treated with red LED light. The skin of apple fruits treated with red or blue LED light showed significantly low EC50 values. Conclusion. These results suggest that red LED irradiation may be used in a controlled environment such as a greenhouse to increase the anthocyanin synthesis and antioxidant activity in apple skin.

Role of abscisic acid in regulating fruit set and ripening in squash (Cucurbita pepo L.)

ABSTRACTSquash is a non-climacteric fruit, so the release of ethylene plays a limited role in the ripening process; however, there is a large accumulation of abscisic acid (ABA) during fruit maturation and ripening. To investigate the contribution of ABA in squash fruit development, the CpNCED1 gene, which encodes the key enzyme in ABA biosynthesis (9-cis-epoxycarotenoid dioxygenase [NCED]), was cloned from squash fruit, and its transcriptional regulation during fruit development, dehydration and pollination was analysed using a quantitative reverse transcription polymerase chain reaction (qRT-PCR). The expression of CpNCED1 peaked 20 days after full bloom (DAFB) in the pulp and seed, and 25 DAFB in the peel, all of which corresponded with the accumulation of ABA. The application of exogenous ABA increased the expression of CpNCED1 and the release of ethylene, thereby promoting fruit ripening. The expression of CpNCED1 was also induced by dehydration stress and pollination. These findings show that ABA plays important roles in squash fruit ripening, and in the plant’s response to dehydration stress and early fruit set via the transcriptional regulation of CpNCED1.

Translocation and accumulation of fruit-fixed photosynthate in Satsuma mandarin

Satsuma mandarin fruit (Citrus unshiu Mark.) photosynthesizes as comparable to leaf at about 100 days after full bloom (DAFB). In this study, translocation and accumulation of fruit-fixed photosynthate were investigated by using 14CO2. When fruit at 108 DAFB was exposed to 14CO2 for 48 h under 135 photosynthetic photon flux density (PPFD), 14C-sucrose, 14C-glucose and 14C-fructose were detected not only in flavedo but juice sac; more than 50 % of fruit assimilated 14C-sugars were present in juice sac. Thus, majority of rind-fixed photosynthate are infiltrated into juice sac and accumulated there within 48 h after assimilation. Although 14C-sucrose was predominant at flavedo where high SS (sucrose synthase) activity toward synthesis was present, the amount decreased gradually from the outside (flavedo) to the inside (juice sac) of fruit. In vascular bundle, strong SS toward cleavage and soluble acid invertase activities were involved, and 14C-fructose was predominant in juice sac. Accordingly, rind-fixed photosynthate is once converted to sucrose, the translocated sugar in Citrus, at flavedo by SS toward synthesis, and loaded on vascular bundle through symplastic and/or apoplastic movement in the albedo tissue. In the vascular bundle, sucrose may be degraded by SS toward cleavage and invertase, and resulting hexoses transported symplastically to the juice sac through juice stalk.

Effect of exogenous GA3 and its inhibitor paclobutrazol on floral formation, endogenous hormones, and flowering-associated genes in ‘Fuji’ apple (Malus domestica Borkh.)

Gibberellins (GAs) reduce apple (Malus domestica) flowering rates; however, the mechanism of their action is not fully understood. To gain a better insight into gibberellin-regulated flowering, here, 5 year-old ‘Fuji’ apple trees were used to explore the responses of hormones [GA1+3, GA4+7, indole-3-acetic acid (IAA), zeatin-riboside (ZR), and abscisic acid (ABA)], and gibberellin- and flowering-associated genes, to applications of gibberellin acid (GA3) and paclobutrazol (PAC). Results showed that GA3 relatively stimulated vegetative growth and delayed floral induction. Moreover, GA3 spraying significantly affected contents of all endogenous hormones and all the genes tested in at least one time points: the content of endogenous GAs was increased instantly and that of ZR was reduced at 44 days after fullbloom (DAF), which might constitute an unfavorable factor for flower formation; MdKO (ent-kaurene oxidase gene) and MdGA20ox (GA20 oxidase gene) were significantly repressed by a high level of GAs through the negative feedback regulation of GA; additionally, the MdSPLs (SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE) in this study were all significantly repressed by GA3 but promoted by PAC; the expression of MdFT1/2 (FLOWERING LOCUS T), MdSOC1 (SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1) and MdAP1 (APETALA1) in GA3-treated buds changed in the same way, and they were repressed at 44 DAF. We suppose that GA3 spraying disrupts the balance between ZR and GAs, and inhibits floral induction, probably by suppressing MdSPLs and the floral integrators in flower induction, which ultimately contributed to inhibiting flower formation.

Chemical thinning affects yield and return flowering in 'Jubileu' peach

ABSTRACT Peach hand thinning improves fruit quality; however, it requires a high demand of labor and increases production costs. The objective of this study was to evaluate the effect of growth regulators applied at post-flowering as an alternative to hand thinning of peaches. The experiment was conducted with peach cultivar Jubileu, in 2012. The treatments consisted of no thinning, hand thinning 45 days after full bloom (DAFB), ethephon (85 and 120 mg L-1), benzyladenine (BA) (400 mg L-1), and BA plus gibberellic acid (GA4 + 7) (400 mg L-1) applied 40 DAFB. BA-treated plants were not different from non-thinned plants, had excessive load, and smaller diameter fruit. Treatment with ethephon at 120 mg L-1 resulted in excessive thinning and decreased yield in comparison with other treatments. Plants treated with 85 mg L-1 ethephon and BA + AG4 + 7 (400 mg L-1) had fruit abscission, crop load, production per plant and fruit diameter similar to hand-thinned plants. In 2013, an increased number of flower buds was observed in treatments with ethephon and also reduction of this trait in BA and BA + GA4 + 7 applications. Ethephon at 85 mg L-1 can be an alternative of chemical thinning in 'Jubileu' peaches, without compromising the return of flower bud numbers in the next crop.

Evaluation of fruit quality and antioxidant activity of kiwifruit during ripening and after storage

BACKGROUND: In the Northern hemisphere kiwifruit harvest time is conditioned by low temperatures occurring during the harvesting season while in Southern Italy minimum temperatures in autumn are high enough to support fruit growth and ripening. To evaluate the influence of delayed harvest time on kiwifruit quality attributes. METHODS: The experiment was carried out in a commercial kiwifruit, ‘Hayward’, orchard located in Southern Italy. In this area, the conventional harvest time occurs 160 days after full bloom (DAFB), during the first decade of November. Fruits were collected from 130 DAFB to 192 DAFB. Fresh fruit and dry weight, flesh color, firmness, total soluble solids content (TSS), titratable acidity (TA), ascorbic acid (AA), total polyphenols content (TPH) and antioxidant capacity (TAC) were determined. After 120 days of storage, fruit harvested 178 DAFB, had higher fresh and dry weight, flesh firmness, TSS, TA and lower water loss than fruit harvested at 160 DAFB, with no significant differences in AA, TPH and TAC. TAC was correlated more to TPH than to AA. Early (130–158 DAFB) harvests, resulted in poor fruit quality and scarce post harvest maintenance. Delaying fruit harvest time, in mild winter areas such as Southern Italy, resulted in an improved fruit