Effects of temperature on fruit thinning with ethephon in ‘Golden Delicious’ apples

The effect of temperature on the ability of 2-chloroethylphosphonic acid (ethephon), when applied at 20 mm stage of fruit development, to induce ethylene evolution of fruit and leaves and abscission of fruit and leaves was determined using 9-year-old root-bagged ‘Golden Delicious’/M.27 apple (Malus domestica Borkh.) trees in environment-controlled growth rooms. Ethephon at 400 μL L⁻¹ effectively thinned apples, and its thinning effect was not affected by increasing day/night temperature from 21.1/10 to 32.2/21.1 °C. Fruit ethylene evolution was enhanced by application of ethephon. Peak fruit ethylene evolution occurred 1 day after application of ethephon when day/night temperature was 32.2/21.1 °C whereas it occurred 2 days after application of ethephon at a day/night temperature of 21.1/10 or 26.7/15.6 °C. Ethephon increased leaf ethylene evolution drastically but it did not induce leaf abscission regardless of temperature.     

Evaluating pre-harvest foliar calcium applications to increase fruit calcium and reduce bitter pit in ‘Golden Delicious’ apples

In all major apple producing countries, applications of foliar calcium (Ca) products to increase fruit Ca content and reduce the incidence of bitter pit in apples are used. Calcium nitrate (Ca(NO₃)₂), Calcimax and Ca acetate were applied, commencing at three different developmental stages (early, mid and late) of fruit growth. Late Ca(NO₃)₂ (80 days after full bloom (dafb)) applications increased the Ca content of fruit at harvest more than early (six dafb) and mid (40 dafb) applications. There was a trend towards an increase in bitter pit from early to late applications of Ca(NO₃)₂ and Calcimax, confirming previous results obtained when applying only Ca(NO₃)₂. In spite of the very low incidences of bitter pit during these seasons (less than 7%), significant differences between treatments were found between Ca(NO₃)₂ Mid and other treatments in 2004/2005, as well as Ca(NO₃)₂ and Calcimax Early and other treatments in 2005/2006. Ca acetate applications did not show any trends in fruit Ca content or bitter pit incidence when applied during the three stages. Thus, products may differ in efficiency of Ca absorption and effectiveness in decreasing bitter pit in fruit when applied during different developmental stages.     

Volatile production by ‘Golden Delicious’ apples is affected by preharvest application of aminoethoxyvinylglycine

The effect of AVG application on the quality and volatile production of ‘Golden Delicious’ apples, grown in Chihuahua Mexico, was evaluated. AVG (125 g AVG/ha) was applied on apple trees four weeks before harvesting. Apples were harvested 176 days after full bloom and stored at 8 °C for 35 d. Quality parameters and volatile compounds were periodically evaluated. AVG application retarded color changes, and preserved acidity of apples during storage. Ethylene synthesis was also delayed by AVG. Control apples presented higher total soluble solids content than AVG-treated apples at the end of cold storage. Volatile production was affected by AVG application, especially in the case of esters and alcohols, which presented 59% and 33% lower values in AVG-treated apples at the end of storage. A higher concentration of aldehydes was observed at harvest time in AVG-treated apples; however, no difference was observed between treatments during storage. Higher correlations between ethylene production and aldehydes and alcohols were found in control apples (0.98, and 0.98, respectively), than in AVG-treated apples (0.6 and 0.90, respectively). AVG application on ‘Golden Delicious’ apples conferred a variety of benefits, such as delaying maturation, maintaining color, and reducing changes in acidity and total soluble solids. However, AVG treatment negatively affects the production of some volatile compounds.     

Mitigation of severe water stress by fruit thinning in ‘O’Henry’ peach: Implications for fruit quality

Fruit thinning can be used to relieve water stress in peach but it is not known how fruit quality will respond under water limited conditions. To elucidate this, we applied, over the growing seasons of 2003 and 2004, irrigation and fruit thinning treatments to ‘O’Henry’ peach at the onset of Stage III of fruit development. The treatments were full irrigation (FI) and no irrigation (NI) with each receiving three crop load levels: light, commercial and heavy. Fruit size and fruit skin colouration were lower in NI than in FI but the following were higher in NI fruit: firmness, juice titratable acidity and electrical conductivity, and concentrations of dry matter and soluble solids. All the quality parameters were significantly correlated with tree water status, expressed as midday stem water potential. NI fruit matured 5–10 days later than FI fruit. The increased dry matter concentration, juice acidity, and electrical conductivity in NI fruit were indicative of lower quality at harvest. Choosing a light crop load was not effective in improving NI fruit quality except for the size. Since fruit size is the most important fruit quality attribute, its increase might compensate for yield losses resulting from heavy fruit thinning. Nevertheless, when heavy thinning is performed for mitigation of water stress in Stage III, the overall fruit quality will suffer if severe water stress is inevitable because of shortage or lack of irrigation water.     

Growth,yield and fruit quality of ‘Van’ and ‘Stark Hardy Giant’ sweet cherry cultivars as influenced by grafting on different rootstocks

The influence of Adara, CAB 6P, Gisela 5, MaxMa 14, Saint Lucie GF 64 (SL 64), Saint Lucie GF 405 (SL 405), and Tabel rootstocks onto vegetative growth, yield and fruit quality of ‘Van’ and ‘Stark Hardy Giant’ (SHG) sweet cherry cultivars was studied during 10 years after grafting. The experiment was performed in the Ebro Valley (Zaragoza, Spain), on a heavy and calcareous soil. Significant differences in some of these parameters such as vigour, yield, fruit size, soluble solids content (SSC), titratable acidity (TA), skin colour and fruit firmness were examined among rootstocks. In general, the highest vigour, annual and cumulative yield were induced by Adara rootstock, whereas Gisela 5 induced the lowest when grafted with both cultivars. The highest yield efficiency was induced by Gisela 5 due to its low trunk cross-sectional area (TCSA), together with Adara, CAB 6P and Tabel for ‘SHG’ cultivar. Regarding fruit quality, Adara, CAB 6P and MaxMa 14 showed, in general, the highest fruit weight and the more attractive skin colour for both sweet cherry cultivars. Furthermore, the high yield shown by Adara did not significantly affect its fruit size. Cherries of trees grafted on Adara also showed high firmness, which implies a better resistance to post-harvest damage. CAB 6P showed a tendency to induce higher TA. Despite the higher firmness of fruits on Gisela 5 and its tendency to induce higher SSC and ripening index, the smaller size fruits together with the less attractive skin colour resulted in a non-interesting rootstock in terms of fruit quality for our growing conditions. Interesting correlations were found among quality parameters, such as the positive correlation showed by SSC with fruit weight and TA. The work demonstrates that the scion–rootstock combination influences some important sweet cherry attributes such as vigour, yield, fruit size, acidity, skin colour and firmness.     

Tree performance and fruit yield and quality of ‘Okitsu’ Satsuma mandarin grafted on 12 rootstocks

The citriculture in Brazil, as well as in other important regions in the world, is based on very few mandarin cultivars. This fact leads to a short harvest period and higher prices for off-season fruit. The ‘Okitsu’ Satsuma (Citrus unshiu Marc.) is among the earliest ripening mandarin cultivars, and it is considered to be tolerant to citrus canker (Xanthomonas citri subsp. citri Schaad et al.) and to citrus variegated chlorosis (Xylella fastidiosa Wells et al.). Despite having regular fruit quality under hot climate conditions, the early fruit maturation and absence of seeds of ‘Okitsu’ fruits are well suited for the local market in the summer (December through March), when the availability of citrus fruits for fresh consumption is limited. Yet, only a few studies have been conducted in Brazil on rootstocks for ‘Okitsu’. Consequently, a field trial was carried out in Bebedouro, São Paulo State, to evaluate the horticultural performance of ‘Okitsu’ Satsuma mandarin budded onto 12 rootstocks: the citrandarin ‘Changsha’ mandarin (Citrus reticulata Blanco) × Poncirus trifoliata ‘English Small’; the hybrid Rangpur lime (Citrus limonia Osbeck) × ‘Swingle’ citrumelo (P. trifoliata (L.) Raf. × Citrus paradisi Macfad.); the trifoliates (P. trifoliata (L.) Raf.) ‘Rubidoux’, ‘FCAV’ and ‘Flying Dragon’ (P. trifoliata var. monstrosa); the mandarins ‘Sun Chu Sha Kat’ (C. reticulata Blanco) and ‘Sunki’ (Citrus sunki (Hayata) Hort. ex. Tanaka); the Rangpur limes (C. limonia Osbeck) ‘Cravo Limeira’ and ‘Cravo FCAV’; ‘Carrizo’ citrange (Citrus sinensis × P. trifoliata), ‘Swingle’ citrumelo (P. trifoliata × C. paradisi), and ‘Orlando’ tangelo (C. paradisi × Citrus tangerina cv. ‘Dancy’). The experimental grove was planted in 2001, using a 6 m × 3 m spacing, in a randomized block design. No supplementary irrigation was applied. Fruit yield, canopy volume, and fruit quality were assessed for each rootstock. A cluster multivariate analysis identified three different rootstock pairs with similar effects on plant growth, yield and fruit quality of ‘Okitsu’ mandarin. The ‘Flying Dragon’ trifoliate had a unique effect over the ‘Okitsu’ trees performance, inducing lower canopy volume and higher yield efficiency and fruit quality, and might be suitable for high-density plantings. The ‘Cravo Limeira’ and ‘Cravo FCAV’ Rangpur limes induced early-ripening of fruits, with low fruit quality. ‘Sun Chu Sha Kat’ and ‘Sunki’ mandarins and the ‘Orlando’ tangelo conferred lower yield efficiency and less content of soluble solids for the latter rootstock.     

Fruit thinning in ‘Conference’ pear grown under deficit irrigation: Implications for fruit quality at harvest and after cold storage

Fruit thinning in pear is feasible for mitigation of water stress effects. However, it is not well known how fruit quality at harvest and after cold storage is affected by pre-harvest water stress. Even less is known about the effects of fruit thinning on quality under these circumstances. To elucidate these, we applied deficit irrigation (DI) and fruit thinning treatments to ‘Conference’ pear over the growing seasons of 2008 and 2009. At the onset of Stage II (80 and 67 days before harvest in 2008 and 2009, respectively), two irrigation treatments were applied: full irrigation (FI) and DI. FI trees received 100% of crop evapotranspiration (ETc). DI trees received no irrigation during the first three weeks of Stage II to induce water stress, but then received 20% of ETc to ensure tree survival. From bud-break until the onset of Stage II and during post-harvest, FI and DI trees received 100% of ETc. Each irrigation treatment received two thinning levels: no thinning leaving commercial crop load (∼180 fruits tree⁻¹), and hand-thinning at the onset of Stage II leaving a light crop load (∼85 fruits tree⁻¹). Under commercial crop loads, DI trees were moderately water-stressed and this had some positive effects on fruit quality. DI increased fruit firmness (FF), soluble solids concentrations (SSC) and acidity at harvest while no changes were observed in fruit maturity (based on ethylene production). Differences in FF and acidity at harvest between FI and DI fruit were maintained during cold storage. DI also reduced fruit weight loss during storage. But fruit size was reduced under DI. Fruit thinning under DI resulted in better fruit composition with no detrimental effect on fresh-market yield compared to un-thinned fruit. Fruit size at harvest and SSC values after five months of cold storage were higher in fruit from thinned trees than fruit from un-thinned trees. Fruit thinning increased fruit ethylene production, indicating advanced maturity. This may lead to earlier harvest which is desirable in years with impending drought. Fruit thinning is therefore a useful technique to enhance pear marketability under water shortage.     

Temperature affects color and quality characteristics of ‘Pink’ wax apple fruit discs

Red color plays a very important role when wax apple fruits are purchased. Temperature is one of the key factors among those influencing red color development. We evaluated the effects of temperature on color formation and other quality characteristics of ‘Pink’ wax apple fruit discs by using constant, slow-increase, fast-increase, transient shifting to high temperature, shifting to high temperature for different length of time and different day/night temperature regimes. The results show temperature has pronounced effects on quality attributes of wax apple fruit discs. Anthocyanin and total soluble solid (TSS) were greatest in the 20 °C treated discs under constant temperatures. In the slow-increase and fast-increase treatments, quality attributes in disc were better in treatments with a final temperature of 25 °C than of 30 °C. The concentration of soluble sugars (SS), starch, total phenolic compounds (TPC), free amino acids (FAA) and soluble protein (SP) all decreased with increasing temperature. Transient shifting to high temperature of 30 °C for 1-day had no effect on pigmentation but treatment periods from 3- to 5-days had a substantial adverse effect. At 30 °C for 5-days, exposed discs had the lightest weight and shortest diameter as well. Both SS and TPC decreased in the 3- and 5-day treatments. When temperature was shifted from 20 to 30 °C for 2 to 11 days, the widest and heaviest discs were found in the 5-day treatment. Anthocyanin and TSS concentration decreased following increased length of exposure to high temperature. Pigmentation of discs exposed to high temperature treatment was worse than in uncultured controls. Both protein and FAA concentrations decreased after culture. Among the 5 different day/night temperature combinations, discs under 25/20 °C had the highest anthocyanin and TSS concentrations, while those under 30/15 °C had the worst.     

Yield and fruit quality of ‘Gala’ and ‘Fuji’ apple trees protected by white anti-hail net

Covering apple orchards with nets protects them from hailstorms but this changes the amount and quality of the light supplied to the trees. This study was carried out to assess the effects of shade provided by white protection net on yield and fruit quality of apple orchards in Southern Brazil, along three growing seasons (2002/2003, 2003/2004, and 2004/2005). ‘Gala’ and ‘Fuji’ apple trees (on MM111 rootstock, raised as slender spindles, with a spacing of 5.5 m × 3 m) were left uncovered (control trees) or covered with white net. The white net reduced the photosynthetically active radiation (λ = 400–700 nm) accumulated over the trees’ canopy along a day by 18.4%, leading to a higher leaf chlorophyll content in both cultivars, and a higher specific leaf area in ‘Gala’. The shade provided by the net did not affect yield and increased fruit average weight in both cultivars. At harvest, the number of seeds per fruit and severity of russet were not affected by netting in both cultivars, as well as the incidence of watercore in ‘Fuji’. The main beneficial effects of the white net were the reduced incidence of sunburn on ‘Gala’, reduced incidence of bitter pit during cold storage in both cultivars, and reduced incidence of apple scab at harvest and of decay after cold storage in ‘Fuji’. Fruit fly damage in ‘Gala’ (assessed in one season) was reduced by netting. However, netting affected negatively some fruit quality attributes. ‘Gala’ and ‘Fuji’ apples from trees protected by the net had a poor skin color (pale blush and a more intense green background color) at harvest. The net reduced flesh firmness and SSC, and increased the starch index of ‘Gala’ apples at harvest, and reduced flesh firmness and SSC, assessed after cold storage and shelf life, in fruits of both cultivars.     

An intact mitochondrial cox1 gene and a pseudogene with different genomic configurations are present in apple cultivars ‘Golden Delicious’ and ‘Delicious’: Evolutionary aspects

We have characterized the mitochondrial cox1 gene copies in two apple cultivars ‘Golden Delicious’ and ‘Delicious’. Both the cultivars contained an intact copy and a truncated copy of cox1. The intact ‘Golden Delicious’ and ‘Delicious’ cox1 genes, designated G-cox1 and D-cox1, respectively, were both found to be actually transcribed to give an RNA of approximately 1.7 kb. The two intact cox1 and two truncated copies (G-φcox1 and D-φcox1) shared a common 1115-bp segment flanked by four combinations of two different 5′- and 3′-sequences. PCR assay demonstrated that the configurations bearing G-cox1 and G-φcox1 existed in substoichiometric amounts within the mitochondrial genome of ‘Delicious’ whereas substoichiometric molecules carrying D-φcox1 were present in the ‘Golden Delicious’ mitochondrial genome. Although ancestor/descendant relationships cannot be inferred between the G-cox1 and D-cox1 arrangements, the results led us to hypothesize that (1) the 1115-bp segment containing part of the progenitor cox1 was duplicated, thereby generating a pseudo-cox1 copy, and (2) this was followed by homologous recombination across a portion of the 1115-bp repeats which gave rise to the descendant cox1 and pseudo-cox1 arrangements.     

Improving ‘Bing’ sweet cherry fruit quality with plant growth regulators

Final fruit diameter is the prime determinant of sweet cherry fruit value. Previous research has shown that mesocarp cell size accounts predominantly for variability in final fruit size, within a genotype. Our research program evaluated the potential to improve sweet cherry fruit size/weight with growth regulators to affect cell division and/or cell expansion stages. In the current study we screened 8 plant growth regulators (PGRs), including cytokinins, gibberellins, and auxins, and their combinations for their ability to increase ‘Bing’ fruit weight. Each PGR was mixed in lanolin paste and applied to fruit pedicels at 9 or 30 days after full bloom (DAFB), to coincide with estimated peak in cell division and cell expansion activity, respectively. Several cytokinins applied 30 DAFB improved fruit weight significantly (ca. +15%) with N-(2-Chloro-4-pyridyl)-N′-phenylurea (CPPU) and 6-(3-hydroxybenzylamino) purine (mt-Topolin) at 100 mg l⁻¹ being the most effective. Gibberellins, applied alone, improved fruit size and delayed fruit maturation and exocarp coloration. GA₃ at 200 mg l⁻¹ applied at 9 DAFB was the most effective and improved final fruit weight by 15%. Fifty-six percent of the fruit from this treatment were ≥9 g compared to 15% of similar weight fruit from untreated limbs. Both GA₃ and GA_4/7 treatments applied 9 DAFB increased fruit radial expansion. 4-Chlorophenoxyacetic acid, a synthetic auxin, also stimulated higher fruit growth rates at stage I and stage II, and fruit color development, but did not improve final fruit size.     

Growth,yield and fruit quality of ‘Marisol’ clementine grown on four rootstocks in Egypt

To evaluate the most appropriate rootstocks for mandarin production in Egypt, vegetative growth, yield and fruit quality of ‘Marisol’ clementine (as newly introduced cultivar in Egypt) grafted on Sour orange (the common rootstock), Cleopatra mandarin, Carrizo citrange and ‘Swingle’ citrumelo were evaluated under the Egyptian conditions during 2004/2005 and 2005/2006 seasons. Trees were grown in a private farm at ‘Wady El-Mullak’ region, Ismailia Governorate (Latitude, 30°36′ N; longitude, 32°14′ E; Altitude, 10 m above sea level).     

Differences in fruit colour development,anthocyanin content,fruit quality and consumer acceptability of eight ‘Gala’ apple strains

The effect of strain on fruit colour development, chromaticity values and anthocyanin content, fruit quality and consumer acceptance was evaluated on eight ‘Gala’ apple strains (Malus domestica Borkh.) at the IRTA (Spain), during a period from 4 weeks before to 1 week after commercial harvest. Based on fruit colour, measured with a Minolta CR-200 portable tristimulus colorimeter, and anthocyanin content, the most coloured strains were ‘Royal Beaut’, ‘Buckeye Gala’ (both semistriped) and ‘Ruby Gala’ (blushed). ‘Brookfield’ and ‘Schniga’ (both striped) provided an intermediate level of colour, while ‘Galaxy’ and ‘Mondial Gala’ (both striped) were the least coloured ones. The most important increase in colour development was recorded from 2 weeks before the commercial harvest and continued also increasing after harvest. Highly coloured strains developed a red colour on both fruit sides with greater average of fruit surface coloured, while the less coloured strains exhibited different colouration between sides, more bicolour fruits and lower average of fruit coloured.     

Effect of synthetic auxins on fruit development of ‘Bing’ cherry (Prunus avium L.)

The main cherry cultivar grown in the warm climate of Israel, ‘Bing’, produces relatively small fruit. Over three consecutive years (2003–2005), application of 50 mg l⁻¹ 2,4-dichlorophenoxypropionic acid [2,4-DP; as its butoxyethyl ester (Power™)], 10 mg l⁻¹ 3,5,6-trichloro-2-pyridyloxyacetic acid [3,5,6-TPA; as the free acid (Maxim^®)], or 25 mg l⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) plus 30 mg l⁻¹ naphthaleneacetic acid (NAA; 0.3% Amigo™), at the beginning of pit-hardening when fruitlet diameter was ca. 13 mm caused appreciable and significant increases in fruit size and total yield, except when the crop load was heavy. Anatomical studies revealed that the main effect of these synthetic auxins was via direct stimulation of fruit cell enlargement. The above auxins had no negative effect on fruit quality, either at harvest or after 1 month of storage at 0 °C, or on return yield in the following year.     

Grafting effects on postharvest ripening and quality of 1-methylcyclopropene-treated muskmelon fruit

In addition to managing soil-borne diseases in muskmelon (Cucumis melo L.) production, grafting with resistant rootstocks may impact fruit quality. The ethylene antagonist 1-methylcyclopropene (1-MCP) has been shown to extend shelf life of fresh muskmelon fruit. Postharvest characteristics of 1-MCP-treated melon fruit as affected by grafting, however, have not been well examined. This study was conducted to explore the influence of grafting with different rootstocks on ripening and quality attributes of 1-MCP-treated muskmelon fruit during postharvest storage. Grafted ‘Athena’ muskmelon with two commercial squash interspecific hybrid rootstocks including ‘Strong Tosa’ and ‘Tetsukabuto’ as well as non-grafted and self-grafted ‘Athena’ were grown in replicated field plots at the University of Florida Plant Science Research and Education Unit (Citra, FL, USA) during April–June 2010. Half-slip fruit from two harvests were treated with 1.0 μL L⁻¹ 1-MCP (18 h, 20 °C) and analyzed during storage at 13 °C. For fruit from the 27 May harvest, whole fruit and mesocarp firmness, titratable acidity, soluble solids, and ascorbic acid content were measured, while production of ethylene and CO₂ was determined on fruit from the 29 June harvest. Grafting did not show a significant impact on fruit yield but affected the fruit shelf life significantly. Fruit from non-grafted ‘Athena’ and ‘Athena’ grafted onto ‘Strong Tosa’ demonstrated a shelf life of 31 d for the first harvest and 22 d for the second harvest. Shelf life of fruit from self-grafted ‘Athena’ and ‘Athena’ grafted onto ‘Tetsukabuto’ declined by 6 d and 3 d for the first and second harvest, respectively. Whole fruit firmness decreased by approximately 15.5% on average from 13 to 31 d except day 19 as a result of grafting, but to a lesser extent with ‘Strong Tosa’ rootstock. Mesocarp firmness of grafted melon was reduced by about 30.2% at days 13 and 19 compared to non-grafted ‘Athena’ fruit. In contrast, titratable acidity, soluble solid content, and ascorbic acid concentration were less affected by grafting. All the measurements except for ethylene and CO₂ production declined during storage regardless of the grafting treatment. Compared with ‘Strong Tosa’ rootstock, ‘Tetsukabuto’ resulted in a more rapid ripening under 1-MCP application, as reflected by earlier increase in ethylene production and higher respiratory rate. The study demonstrates that grafting effects on postharvest ripening and quality of ‘Athena’ muskmelon can vary markedly with rootstocks used.     

Water relations,growth, yield,and fruit quality of hot pepper under deficit irrigation and partial rootzone drying

We compared two water-saving irrigation practices, deficit irrigation (DI) and partial rootzone drying (PRD), for their effects on growth and quality of ‘Ancho St. Luis’ hot pepper (Capsicum annum L.). The treatments were: commercial irrigation (CI) considered as the control, irrigating both sides of the rootzone with half of the volume of CI considered as DI, and alternating irrigation between two sides of the rootzone with half the volume of CI at each irrigation time considered as PRD. Midday leaf water potentials of PRD and DI plants were lower by 0.15 and 0.30 MPa, respectively, than of CI plants from 130 days after sowing. Total fresh mass of fruit was reduced by 19 and 34.7% in PRD and DI, respectively, compared to CI. Fruit number per plant was reduced by more than 20% in PRD and DI compared to CI. Total dry mass of fruit was similar among the treatments. At harvest, DI fruit had 21% higher total soluble solids concentration and better colour development than other treatments. Although incidence of blossom-end rot was high in PRD and DI fruit, more than 80% of fruit from PRD was not affected. DI and PRD saved 170 and 164 l of water, respectively, compared to CI and they could be feasible irrigation strategies for hot pepper production where the benefit from saving water outweighs the decrease in total fresh mass of fruit.     

金冠苹果树冠内光质构成及其与果实品质的相关性

应用CI-700AB/HR2000光纤光谱仪,研究了田间自然光照条件下金冠苹果树冠内的光质分布及其与果实品质的相关性。结果表明,UV-A、可见光、总辐射、紫光和蓝光,在树冠内分布从上到下、由外到内依次减弱,并与果肉总糖、抗坏血酸、果皮花青苷和类胡萝卜素的分布呈极显著正相关,与果肉可滴定酸和果皮叶绿素呈极显著负相关;UV-B与此相近,但与抗坏血酸呈不显著负相关;红外线则与可见光相反。     

Delayed harvest improves red blush development and quality of ‘Cripps Pink’ apple

The poor red blush development on ‘Cripps Pink’ (Malus x domestica Borkh.) apple fruit at commercial maturity (CM) reduces the economic return to apple growers in warmer regions of the world. The effects of delayed harvest maturity up to 6 weeks following CM on the development of red blush and fruit quality of ‘Cripps Pink’ apple were investigated at two locations in Western Australia during 2003 and 2004. The red blush, export-grade fruit, total anthocyanin, cyanidin 3-galactoside, chlorogenic acid, catechin, and epicatechin of apple fruit skin tissues increased with advancement of harvest maturity at both locations in both years, whereas hue angle, concentration of phloridzin, fruit firmness, and titratable acidity (TA) of apple fruit tissues decreased with delayed harvest. The internal ethylene concentration was elevated with the delayed harvest. The concentrations of quercetin 3-galactoside, quercetin 3-arabinoside, quercetin 3-rutinoside, quercetin 3-rhamnoside, and quercetin 3-glucoside increased up to 2 weeks following CM, and then declined in 2003 at both locations and at Perth Hills in 2004. Delayed harvest resulted in improved development of red blush on the fruit surface, accumulation of total anthocyanin, cyanidin 3-galactoside, chlorogenic acid, catechin, epicatechin, and quercetin glycosides in fruit skin, SSC:TA ratio and reduced fruit firmness possibly due to the increased ethylene production.     

Quality and volatile attributes of attached and detached ‘Pluk Mai Lie’ papaya during fruit ripening

The ‘Pluk Mai Lie’ papaya (Carica papaya L.) is a promising cultivated fruit for use in fresh and processed products due to its firm flesh, but the aroma it releases is flat. Changes in quality and volatile profiles were analyzed during on- and off-tree fruit ripening. Detached fruit ripened faster than attached fruit, accumulating high internal ethylene levels. Aside from peel color, which was redder in on-tree ripened fruit, most quality attributes changed similarly in the two ripening situations. A slight increase in total soluble solids (TSS) was measured from the onset of the preclimacteric stage, whereas titratable acidity (TA) remained stable throughout the development. Whereas 2-ethyl-1-hexanol was found specifically in green fruit, ethyl octanoate emerged only in fully-ripe fruit. Furthermore, benzyl isothiocyanate was the most abundant volatile and was present in fruit at every stage except full ripening. The production of total esters, highly correlated with a loss of firmness and an increase in cavity ethylene accumulation, was about 10-fold higher in off-tree ripened fruit. The levels of methanol and ethanol sources in fruit increased steadily throughout ripening, with esters formed from ethyl alcohol predominating from the half-ripe through the senescence phases. The alcohol dehydrogenase activity in the mesocarp increased dramatically during the early ripening stages, whereas alcohol acetyltransferase was active throughout ripening. No difference in volatile profiles was found in the papaya fruit during on-tree and postharvest ripening.