Non-Destructive Evaluation of Edible Coatings Effects on Keeping Quality of European Plums (<Emphasis Type="Italic">Prunus domestica</Emphasis> L.) by Laser Light Backscattering Imaging

Fruits of European plum (Prunus domestica L.) show high rates of transpiration. Consequently, they are highly perishable fruit. In the present study, the potential of an edible coating (Versasheen®-based with sorbitol as plasticizer) to improve storage life and keeping quality was evaluated on fruit of the plum cultivars ‘Jojo’ and ‘Tophit plus’. Plums were picked at commercial harvest date and stored at 2?±?0.5?°C (90?±?2% rh) for up to 28?d plus 2?d at 20?°C to simulate shelf life. Every seventh day, plums were analysed for transpiration, colour changes and laser light backscattering imaging (LLBI) at a wavelength of 785?nm to non-destructively investigate variations in quality properties of plums. Finally, fruit flesh firmness, soluble solids content, and titratable acidity were determined destructively. Results indicated that coating of fruit of both cultivars increased their surface resistance against water vapour transfer resulting in lower transpiration rates and thus lower mass losses compared to controls. Consequently, coating of fruit considerably delayed the decrease in flesh firmness. Moreover, edible coating retarded the increase of FWHM785 in coated plums. In this context, FWHM785 proved as a rapid and non-destructive tool to monitor changes in mechanical properties in heavily coloured plums. Results highlight that edible coatings successfully extend post-harvest life of plums.     

Thinning apples via shading: an appraisal under field conditions

Summary

Fruit development and the fate of fruits was followed on ‘Imperial Gala’ apple (Malus × domestica Borkh.) trees thinned chemically or using shading. The percentage fruit drop, fruit growth rates using callipers and electronic gauges, and whole tree gas exchange rates were measured before, during, and after covering with a shading cloth that blocked 90% of solar radiation, applied for 1 week starting 30 d after full bloom (DAFB). While fruits were thinned to similar crop loads and all reached a similar size at harvest, their growth patterns reflected the treatments applied, with fruit growth slowing down and fruit dropping sooner in chemically-thinned trees which were treated earlier, than in the shading treatment, which took place later. Daily fruit growth patterns changed and were greatly reduced under shading, as were the net carbon exchange rates (NCER), both in total per tree and per unit of light intercepted by the trees. Regression analysis of the NCER per unit of light intercepted revealed no difference between the two treatments before and after shading, but a significantly lower relationship during shading. This work supports the hypothesis that C-starvation may induce fruit abscission at approx. 30 DAFB. Fruit growth patterns, and their changes during shading, were consistent with this hypothesis. This method of thinning, may be of interest to reduce the use of chemicals, and in organic fruit growing. However, before it can be adopted, a method to estimate the length of the period of shading is required.     

Effects of fruit thinning,pollination and paclobutrazol on fruit set and size of persimmon (Diospyros kaki L.) in subtropical Australia

Summary

A factorial combination of three cultural factors (± hand-pollination, ± growth retardant, ± fruit thinning) were evaluated for their effects on fruit set and fruit size of ‘Fuyu’ persimmon (Diospyros kaki L.) in subtropical Australia (Lat. 27° S). Treatments were applied to individual shoots on mature seven year old trees. Fruit set of pollinated flowers was high compared with non-pollinated flowers (91% vs. 47%). Pollinated fruit also grew faster at all stages of fruit development and, at harvest, fresh weights were 25% heavier. Palcobutrazol significantly (P<0.05) increased fruit weight by 7% compared with controls but did not increase fruit set. Irrespective of treatment, fruit weight was not correlated (r<0.3, n.s.) with shoot length, number of nodes per shoot, fruit nodal position, shoot dry weight, leaf area per shoot, and number of leaves per shoot. Fruit fresh weight was only poorly correlated with shoot base diameter (r = 0.41*). Pollinated fruit had significantly (P<0.05) higher concentrations of nutrients (N, K, Ca, and Zn).     

Tree yield and fruit minerals concentrations influence ‘Hass’ avocado fruit quality

To investigate the variation in quality of ‘Hass’ avocado fruit within an orchard, fruit were harvested at commercial maturity from 15 ‘Hass’ trees of similar appearance, growing in three adjacent rows on the same soil type, and receiving similar management. Fruit were harvested at commercial maturity, and either ripened at 22 °C or stored at 2 or 7 °C for 3 or 5 weeks and then ripened. Significant positive correlations (based on the mean for each datum tree) were noted between fruit flesh calcium (Ca) and magnesium (Mg) concentrations and the (Ca+Mg)/potassium ratio, and the number of days for the fruit to reach the eating ripe stage (DTR). Negative correlations were also observed between these minerals and anthracnose and mesocarp discolouration (MD) severity. Negative correlations were observed between fruit potassium (K) and phosphorus (P) concentrations and DTR. Fruit from trees with high fruit yield were generally smaller, with lower anthracnose and MD severity, ripened more slowly, and had higher flesh Ca concentrations. It is likely that cultural practices that maintain moderate to high fruit yield and reduce variation in yield will improve avocado fruit quality and reduce variability in quality. Since the main differences between adjacent trees in this trial were the seedling rootstocks of unknown origin, it is suggested that rootstocks can have a significant impact on avocado yield and fruit quality.     

Evaluating the effectiveness of different strategies for calcium application on the accumulation of calcium in apple (Malus × domestica Borkh. ‘Braeburn’) fruit

Summary

Orchards displaying calcium (Ca) deficiency are a common phenomenon worldwide, despite the presence of sufficient Ca in the soil and the plant. A 3-year trial was conducted between the 2007 – 2008 and 2009 – 2010 growing seasons to evaluate the contributions of soil and foliar Ca applications to Ca concentrations in ‘Braeburn’ apple (Malus × domestica Borkh.) fruit. Ca(NO₃)₂ (Calflo; Yara Africa, Fourways North, South Africa) was applied as six separate foliar sprays until run-off. Applications were made at 1-week intervals between approx. 21 – 70 d after full bloom (DAFB) at 6.75 ml l^–1. Soil applications of Ca (Tropicote^TM; International ASA, Oslo, Norway) at 300 kg ha^–1 were applied at fruit set, or after harvest, according to standard practice. Mineral analysis was conducted to assess the soluble Ca concentrations of whole fruit (without pips and stalks), to quantify the contribution of foliar sprays or soil-applied Ca. Fruit Ca concentrations were maintained at satisfactory levels (4.5 mg Ca 100 g^–1 FW) at harvest by applying a series of six foliar sprays early in the season (for all seasons) during the trial period. Fruit Ca concentrations at 80 DAFB were highest in the treatments with foliar applications of Ca. In 2009 – 2010, Ca concentrations in apple fruit were lowest (8.38 mg 100 g^–1 FW) for soil application of Ca at fruit set. Ca applications to soil after harvest in the previous season, and soil applications shortly after fruit set in the current season, did not significantly increase Ca concentrations in current-season fruit, providing soil Ca levels were above the minimum requirement for apple trees. A possible explanation is that apple trees regulate their uptake of Ca through the roots when soil Ca is available in sufficient quantities. This confirms the importance of active root growth for efficient Ca uptake by apple trees when applying Ca to the soil.     

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.     

Rootstock influence on ‘delicious’ and ‘golden delicious’ apple fruit quality at harvest and after storage

The influence of 9 rootstocks (M2, M7, M25, M26, MM104, MM106, MM109, MM111 and seedling) on fruit quality at harvest and after storage of ‘Wellspur Delicious’ (WS) and ‘Goldspur’ (GS), and of 3 rootstocks (M7, M26 and MM106) on fruit quality of ‘Red King Delicious’ (RK) and ‘Golden Delicious’ (GD) apple (Malus domestica Borkh.) was evaluated during a 4-year period. Fruits from trees on M26 were larger, developed earlier color and soluble solids (SS), and maintained higher levels of acidity (at harvest and during storage) in comparison with other rootstocks. Fruit from trees on M2 tended to have high SS. Fruit color from trees on MM104, MM106 and MM109 tended to be comparatively poor. There were significant rootstock effects on SS, starch, acidity, color, circumference, weight and box size.     

Improvement of fruit quality and storage potential of ‘Braeburn’ apple through deficit irrigation

Summary

We explored the potential of deficit irrigation (DI) applied at different times during the growing season for improving fruit quality and storage potential of ‘Braeburn’ apple growing in a commercial orchard. Because DI often reduces fruit size, effects of fruit size on fruit quality were also examined. The irrigation treatments were: commercially irrigated control (C), early deficit irrigation (EDI) applied from 63 to 118 d after full bloom (DAFB), and late decifit irrigation (LDI) applied from 118 DAFB to final harvest on 201 DAFB. Both EDI and LDI improved fruit quality in terms of increases in: dry-matter concentration (DMC) at harvest, flesh firmness, total soluble solids, and total soluble sugars both at harvest and after storage. The DI fruit had less weight loss during storage than did C fruit. Deficit irrigation affected the concentrations of a few individual aroma volatiles but not total volatile concentration. Incidence of physiological disorders was not affected by irrigation treatments. Mean fruit weight was lower in DI than in C but the difference was not significant. Among the quality attributes studied, only firmness and DMC were affected by fruit size with their values being higher in smaller fruit.     

Einfluss von Biostimulanzien und Lichtreflexionsfolie auf die Fruchtqualität und Farbentwicklung bei Apfel

The aim of this research was to improve inner and external fruit quality and fruit colouration using four-year-old apple ‘Braeburn, Hillwell’ trees on M9 (3?m × 1?m spacing) by employing reflective ground covers and biostimulants at Klein-Altendorf, nr. Bonn, Germany (50°N). Two reflective ground covers were spread on both sides of tree rows seven weeks before anticipated harvest and two biostimulants were applied two times – four and two weeks before harvest. Adjacent trees of the same row without reflective ground cover or without biostimulants served as control.Reflective ground covers significantly improved red colouration from 71°hue in the control to 49°hue with the ground cover Lumilys® and to 40°hue with Extenday®. The red colouration of the lower surface of fruits improved from 85°hue in the control to 52°hue with Lumilys® and 40°hue by Extenday®. Apple trees with Extenday® and Lumilys® produced 69% and 44% well-coloured fruit (with 75–100% fruit colouration) compared with 16–26% in the control.By contrast, an acceleration of ripening processes was not observed in plots with reflective ground covers compared with the control. There were no differences in sugar contents (°Brix) and fruit firmness (kg/cm²), but starch breakdown in fruit with reflective mulch was significantly delayed compared with the control resulting in retarded maturation.An economic analysis based on material costs and lifespan – excluding the labour costs for spreading and removing the ground covers – showed an economic advantage, if these mulches are used more than once a year.Both biostimulants showed neither effects on inner and external fruit quality nor on fruit colouration. Fruits with Wuxal®ATRiun or Sunred® did not improve the percentage of well-coloured fruits (75%–100% fruit surface with red colouration) compared with the untreated control. Similarly, inner and external fruit quality showed no significant differences in fruit firmness, sugar content and starch degradation. An economic analysis based on chemicals’ costs – excluding the labour costs for applying the biostimulants – resulted in no economic advantage. The chlorophyll – based ‘Index of Absorption Difference’ (IAD; measured non-destructively by the DA-meter) in some cases correlated positively with the Streif (maturation) index based on destructive assessment fruit firmness, sugar content and starch breakdown in an ‘ART system’.     

Determination of optimal harvest boundaries for ‘Ambrosia’ apple fruit using a delta-absorbance meter

In this study, a new chlorophyll measurement tool, the delta absorbance (DA) meter, was used to develop an optimal harvest maturity model for ‘Ambrosia’ apple (Malus × domestica Borkh.) fruit. Fruit from four commercial orchards in the Annapolis Valley, Nova Scotia, Canada, were sampled (25 fruit from three or four trees per location) over nine consecutive weekly harvests during the 2011 and 2012 growing seasons, and 8 weeks in the 2013 season. At each harvest, five fruit from each orchard site had their index of absorbance difference (I_AD) values, firmness, mass, titratable acidity (TA), soluble solids content (SSC), red skin colouration and internal core ethylene concentrations measured. Following approx. 3 months of storage at 3.5°C, 20 fruit from each site were removed and assessed for the incidence of disorders such as senescent breakdown, cortical browning and coreflush. Chlorophyll concentrations in the epidermis were strongly and positively related to I_AD values in the same tissue (P ≤ 0.001), confirming the assumption that chlorophyll was the basis for the DA meter I_AD signal. In addition, I_AD values declined significantly during fruit maturity and were negatively related to harvest week (P ≤ 0.001). The optimum harvest period was identified by aligning all ‘at harvest’ I_AD values, fruit quality measurements, and ‘post-storage’ disorder data with the corresponding harvest week. I_AD values associated with harvests having the highest commercial fruit quality then delineated the optimal harvest boundaries. The upper boundary I_AD value of 0.47 was defined as ‘when to begin harvest’, while the lower boundary I_AD value of 0.28 was considered to be ‘when to end harvest’ for long-term storage. The use of a DA meter and its I_AD value to define the optimal harvest boundaries may be applicable to all commercial apple cultivars, but should be developed for each cultivar and growing region.     

单性结实与自花结实柑橘果实发育中钙钾动态的研究

 对单性结实的‘国庆1 号’温州蜜柑和自花结实的‘华农本地早’橘从开花前子房发育至果实成熟采收期整个子房或幼果及果实的不同部位(果皮和果肉) 的钙与钾含量变化进行了测定。结果表明:1) ‘国庆1 号’花前及花期子房钙含量较高, 花后趋降; 而其钾含量在花前及花期相对较低, 花后上升;2) ‘华农本地早’花前子房钙含量相对较低, 花后有一上升过程; 而对应钾在花前及花期就已很高, 花后下降; 3) 两品种果肉的钙含量自花后65 d 后均呈下降趋势, 而‘国庆1 号’果皮的钙含量在花后80 d 有一显著上升, 对应的‘华农本地早’在花后125 d 才急剧增加, 之后直至果实成熟二者均维持在较高水平;4) 两品种果皮、果肉的钾含量在果实发育过程中均呈类似的下降趋势。     

Effects of 1-aminocyclopropane carboxylic acid on the rate of ethylene release from detached fruiting spurs and on fruit abscission in apple

Summary

1-Aminocyclopropane carboxylic acid (ACC) was applied to apple (Malus × domestica Borkh.) trees or to individual fruiting spurs between full bloom (FB) and 31 d after full bloom (DAFB; mean fruit diameter of 20 mm) to determine the effects of ACC on the ethylene released from detached spurs and on fruit abscission. The rate of ethylene release from detached fruiting spurs increased 1 d after applying 50 mg l^–1 ACC at full bloom or 16 DAFB (mean fruit diameter of 10 mm), but ACC had a reduced effect on the rate of ethylene release when it was applied 31 DAFB (mean fruit diameter of 20 mm). ACC reduced fruit set in ‘GoldRush’ apple in a concentration-dependent manner in 2009 and in 2010, but had no thinning activity on ‘Pink Lady’ in 2010. ACC at 200 mg l^–1 resulted in the yellowing and abscission of ‘GoldRush’ spur leaves in 2009, but not in 2010. The effects of combining ACC and 5 mg l^–1 naphthaleneacetic acid on fruit set in ‘GoldRush’ apple were additive. The application of 200 mg l^–1 ACC when fruit are ca. 10 mm in diameter may therefore be a useful chemical thinning treatment for apple fruit.     

The role of Pre-harvest Aminoethoxyvinylglycine (AVG) Treatments on Total Phenolics,Antioxidant Capacity and Fruit Quality Attributes of Sweet Cherry Cultivars

The present study was conducted to investigate the effects of pre-harvest aminoethoxyvinylglycine (AVG) treatments on fruit quality parameters and bioactive compounds of sweet cherry fruits (Prunus avium L. cvs. ’0900 Ziraat’, ‘Regina’ and ’Sweetheart’). Whole trees were sprayed once with an aqueous solution containing AVG (0, 100 and 200?mg L^?1) three weeks before the anticipated commercial harvest. Measurements were performed a week before anticipated harvest date, at anticipated harvest date and a week after anticipated harvest date. AVG treatments significantly maintained flesh firmness of all three sweet cherry cultivars. Harvest was delayed at least for a week through the keeping of flesh firmness with AVG treatments. The treatments slowed down the red skin color development in all three cultivars. The measurements performed over fruits collected at different ripening stages revealed that AVG resulted in decreased total phenolics and total anthocyanin and ultimately decreased antioxidant capacity in sweet cherry fruits. AVG treatments also decreased soluble solids content and increased titratable acidity of the fruits. This study revealed that pre-harvest AVG treatments were more effective in delaying sweet cherry fruit softening. The main advantage is to maintain the firmness of late-harvested fruit by retaining fruit quality attributes of sweet cherry fruit.     

Can Mineral Analysis be Used as a Tool to Predict ‘Braeburn’ Browning Disorders (BBD) in Apple in Commercial Controlled Atmosphere (CA) Storage in Central Europe?

‘Braeburn’ apples stored in controlled atmosphere (CA) frequently present internal flesh browning physiological disorder which is commonly referred as ‘Braeburn’ Browning Disorder (BBD). Apples from different orchards, years or site conditions can vary considerably in their sensitivity. The aim of this research was to evaluate the relationship between the mineral status of ‘Braeburn’ apples before-harvest (18 days) and at early and normal harvest, to correlate the data with the BBD incidence found in apples post storage and to investigate possible reasons for differences in disorder sensitivity. Fruits from seven orchards in the Lake Constance area (South-Western Germany) were harvested at two picking dates and the mineral content was measured before-harvest, at-harvest and during storage. Fruit were stored at 1.5?°C under CA conditions (1 kPa O₂ and 0.5 kPa CO₂) using either a 10 days or a 24 days delayed establishment of CA conditions. Fruit were evaluated after 6 months of storage plus 10 days of shelf life at 18?°C for mineral status and the browning disorder incidence. Results indicate no significant changes of the mineral concentrations in the fruit during CA-storage. Significant correlations between the post storage BBD incidence with K, and in some cases also for the K/Ca ratio and for P at-harvest were found.     

Verfrühung von Süßkirschen unter geschlossener Folie

The sweet cherry cvs. ‘Burlat’, ‘Earlise’, ‘Samba’, ‘Souvenir’, and clone M, all with early ripening, large, dark, red-black fruit, were cultivated at a spacing of 3.80x1.75 m under complete rain cover in a whole orchard at the Klein-Altendorf Research Station near Bonn, Germany during April and May 2004. Under such cover, these sweet cherry trees flowered 6–13 days earlier and their fruit ripened 12–19 days earlier than those from uncovered control trees, indicating shorter or enhanced fruit development and maturation in up to 1 week. The cover proved insufficient for frost protection at night, despite increased daytime air and soil temperatures (by as much as 15°C and 5°C, respectively). Trickle irrigation was used to overcome loss of soil moisture due to the rain cover. Burlat leaves grown under this cover were thinner and softer and contained less chlorophyll a, chlorophyll b, and total chlorophyll than the leaves of uncovered control trees, without limiting photosynthesis. In contrast, the chlorophyll content of clone M leaves grown under cover equalled that of uncovered controls. Three of the five cvs. employed developed fruit mass of 9–15 g (25–33 mm fruit diameter). Three-year-old sweet cherry trees on dwarfing GiSelA 5 rootstocks were more vigorous than those without cover and produced 3–4.5 kg fruit per tree. The cover had no adverse effect on fruit colouration. The cherries grown under cover were slightly smaller, softer, with attractive colouration, and tasted better due to increases in both sugar and acidity, with sugar:acid ratios of 25–30:1.     

Postharvest handling practices and irradiation increase lenticel discolouration in ‘B74’ mango fruit

‘B74’ mango is a recently commercialised cultivar in Australia, with an appealing skin colour and firm fibreless flesh. However, fruit can develop lenticel discolouration (LD) after harvest, with loss of commercial value, especially after γ-irradiation as a disinfestation treatment. We hypothesised that postharvest practices could increase fruit sensitivity to LD and tested that by sequentially sampling fruit between the orchard and the end of the packing line over two seasons, followed by ripening without and with irradiation treatment. Exposure of 441–610 Gy γ-irradiation significantly increased the severity of LD by 6.8-fold in commercially picked and packed ripe fruit, reducing the proportion of marketable fruit from 98% to 2%, compared to irradiated fruit harvested directly from the trees and not exposed to de-sapping solution and packing operations. Also, LD increased progressively as the fruit passed through the harvesting and packing processes, and exposure to only bore water increased LD severity compared with no water contact. Results suggest that the typical de-sapping process used during harvesting is a major contributor to skin sensitivity to LD in ‘B74’ mango fruit, and that other packing operations involving wetting of the fruit have an additive effect on it. These effects are exacerbated if fruit is irradiated.     

Verfrühung von Süßkirschen im Folienhaus

Early ripening sweet cherry cvs ‘Burlat’, ‘Earlise’, ‘Samba’, ‘Souvenir des Charmes’ and clone M, which are all characterised by large fruit size and dark red fruit, on GiSelA 5 rootstock were forced – by closing a polytunnel from 24 March to 20 April 2006 – at Klein-Altendorf research station of Bonn University. A portable gas heater was used for automated frost protection in April. An adjacent uncovered planting at the same spacing of 3.8?m?×?1.75?m served as control. Forcing resulted in a 16–18 days earlier flowering in April relative to the 12–16 days earlier harvest at the beginning of June, resulting in a 2–4 days longer fruit development and retarded ripening. PAR was reduced in the polytunnel by 40% on sunny and 30% on overcast days with a concurrent drop in the humidity to 30% on sunny and 40% on overcast days and nearly 100% relative humidity at night. Polytunnel air temperatures on sunny days were increased – during ventilation – by up to 6?°C relative to the outside, e.g. 33?°C versus 27?°C outside. Forced cherries saved one spray application against aphids compared to those outside. Fully-grown cherry leaves contained 40–60?mg chlorophyll/g FM sufficient for photosynthesis with commensurate chlorophyll contents when grown in the polytunnel compared with those outside, and were deficient in calcium (0.5% DM) and magnesium (0.2% DM), but with a surplus in both nitrogen (3.5% DM) and phosphorus (0.42% DM). The surplus leaf nitrogen was due to excessive nitrogen mineralization in the rich soil under the higher temperatures in the polytunnel which caused the vigorous vegetative growth despite the dwarfing rootstock. Great fluctuations in fertilisation – despite strong flowering and sufficient pollination with honey bees – of between 4–71% may be due to the combination of S-alleles of the cherry varieties, infrequent water supply, nutrient imbalance and microclimate. Trees of cv. ‘Burlat’, ‘Earlise’ and clone M in their fourth leaf yielded an average of 2.5–7.5?kg fruit with 15?kg/tree in one case. Fruit of forced cvs. ‘Burlat’, ‘Souvenir’ and ‘Samba’ were larger compared with those of cv. ‘Earlise’ and clone M, which were smaller as a result of increased fruit load on the tree than those from uncovered control trees. For all five cvs tested, except forced cv. ‘Earlise’, a fruit mass of between 10?g (28?mm ) and 12?g (30?mm) and a sugar content of 12–17% with sugar:acid ratios of 20–37:1 made their fruit suitable for marketing as superior or premium fruit at higher farm-gate prices of 4.5–8?€/kg. Fruits were sufficiently dark red or black and firm for short distance transport and rapid sale. An economic evaluation showed financial gains, when yields exceed 8?kg fruit per tree per year at a farm-gate price of 4.50?€/kg.     

Influences of gibberellins A4, A4+7 and A4+iso-A7 on apple fruit quality and tree productivity. II. Other effects on fruit quality and importance of fruit position within the tree canopy

Post-bloom gibberellin sprays increased fruit length:diameter (L/D) ratio and juice soluble solids but did not influence flesh firmness of ‘Golden Delicious’ apples grown in a maritime (Québec) or desert (Okanagan Valley, B.C.) climate. Irrespective of GA treatment, ‘exterior’ fruit at both Canadian locations was larger, yellower, exhibited less russet, and contained more soluble solids at harvest than ‘interior’ fruit. Fruit shape (L/D ratio) was not influenced by position of the fruit within the canopy. Correlation analyses showed that surface russet development is poorly related to seed set, fruit size and other measures of fruit quality. However, a correlation matrix examining the degree of interrelatedness of all fruit size, fruit development and fruit quality indices revealed other relationships that may provide clues to understanding the relationship between fruit growth and quality development of ‘Golden Delicious’ apple.     

The Influence of Shoot Competition on Fruit Retention and Cropping of Apple Trees

Fruit set was increased by removing all shoots 5 days after full bloom and at weekly intervals thereafter from trees of Sunset and Laxton’s Fortune, but removing shoots from Fortune trees 25 days after full bloom produced no beneficial effect on fruit retention. All treatments resulted in a heavier rate of fruit shedding during the ‘June drop’ period than occurred from control trees, and at harvest the trees without shoots had fewer fruits, and lower yields, than the controls. In a comparison of shoot removal and shoot tip removal starting 15 days after full bloom on Fortune trees, both treatments improved set, but whereas shoot removal caused a heavier ‘June drop’ compared with untreated trees, shoot tip removal increased the number of fruits retained to harvest and produced a yield increase. The difference between the two treatments in their influence on fruit retention, during and after the ‘June drop’, is accounted for by the beneficial effect of a relatively small number of leaves on each tipped shoot. Studies on the pattern of distribution of photosynthates, using ¹⁴CO₂ and autoradiography, produced results supporting the concept of competition between fruits and shoots and also showed changes in the pattern of assimilate movement brought about by shoot tip removal. It is concluded that competition between fruits and shoots, occurring during blossoming and the following 2–3 weeks, may limit fruit set, but the presence of shoot leaves is beneficial to fruit retention in the later part of the season, particularly during the ‘June drop’ period.     

Leatheriness and mealiness of peaches in relation to fruit maturity and storage temperature

Summary

`Huangjin' peaches (Prunus persica Batsch) were harvested at commercial harvest time (commercial) and 20 d before (early) or after (later) commercial harvest. Fruit from each harvest were stored at three temperature regimes (0, 5 and 10°C) at 95% r.h. After four weeks of storage at 0 or 5°C, early harvested fruit developed more leatheriness but less mealiness and later harvested fruit did not develop leatheriness but developed more mealiness comparedwith fruit from commercial harvest. Overall, fruit stored at 5°C developed more mealiness but less leatheriness than fruitat 0°C for the same period of storage. When stored at 10°C for two weeks, after which fruit were senescent, fruit did not develop any leatheriness or mealiness regardless of harvest times. Fruit with leatheriness were firmer (>30 N) thanjuicy or mealy fruit (<10 N) after the same period of cold storage and 4 d at 20°C. Mealy fruit were as soft as juicy fruit. 1-Aminocyclopropane-1-carboxylate oxidase (ACO) activity, 1-aminocyclopropane-1-carboxylic acid (ACC) content, and polygalacturonase (PG) and galactosidase (GAL) activities were lower, and insoluble pectin content was higher in leathery fruit than that in juicy or mealy fruit. ACO, PG and GAL activity, ACC, and insoluble pectin content were similar between mealy and juicy fruit.