Fruit quality in ‘Cripp's Pink’ apple,especially colour,as affected by preharvest sprays of aminoethoxyvinylglycine and ethephon

‘Cripp's Pink’ apple grown in Western Australia often develops poor colour at commercial harvest resulting in economic losses. To determine if fruit colour could be improved without advancing ripening, ‘Cripp's Pink’ apple fruit on trees were sprayed with aminoethoxyvinylglycine (AVG) alone, ethephon alone, or AVG followed by ethephon. The experiments were conducted at two different locations in Western Australia in 2002 and 2003. Fruit sprayed with AVG alone had retarded colour development at harvest. However, ethephon applied after AVG enhanced percent red blush, anthocyanin concentration and reduced chlorophyll concentration in the fruit skin in both locations. These fruit had similar colour to those treated with ethephon alone. Internal ethylene concentration and fruit firmness were unaffected by the different treatments in 2002. However, in 2003 AVG with or without ethephon reduced internal ethylene concentration and maintained firmness compared to ethephon alone. In conclusion, AVG treatment alone delayed colour development and ripening of ‘Cripp's Pink’, while AVG application 5 weeks before harvest followed by an ethephon application 2 weeks later enhanced red colour at commercial harvest. This is, therefore, an effective tool for improving colour of ‘Cripp's Pink’ apples at commercial harvest without adversely affecting other fruit quality attributes.     

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.     

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.     

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.     

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.     

Chemical changes during myrtle (Myrtus communis L.) fruit development and ripening

The chemical composition of fruit belonging to ‘Barbara’ and ‘Daniela’ myrtle cultivars was monitored during development from fruit-set to an over-ripe stage (July–January), with the aim to identify a reliable maturity index. Acidity, pH, reducing and total sugars, phenols, tannins, anthocyans, carbon dioxide and ethylene production rates were monitored over two different year seasons. Titratable acidity decreased during maturation, with significant differences due to cultivar and year of observation. Reducing sugars increased in both cultivars approximately sevenfold from fruit set to complete maturation. Total sugar content increased similarly ranging from 1.43% and 1.41% at fruit set to 8.28% and 7.56% at maturation for ‘Barbara’ and ‘Daniela’, respectively. Total phenols and tannins occurred at high levels after fruit set and declined during development. Anthocyans levels increased, in both cultivars, according to a sigmoid curve. The pattern of respiration rate showed a gradual decline in both cultivars ranging from 365.81 and 396.42 mg kg⁻¹ h⁻¹ to 79.98 and 52.27 mg kg⁻¹ h⁻¹, respectively for ‘Barbara’ and ‘Daniela’ in 2006. A peak of variable size was observed in October–November period. Small increases in ethylene production have been detected during fruit development ranging from 130.57 and 269.14 μL kg⁻¹ h⁻¹ measured at the onset of development to 13.04 and 19.36 μL kg⁻¹ h⁻¹ measured at harvest for ‘Barbara’ and ‘Daniela’, respectively.     

Harvest and post-harvest apple fruit quality following applications of kaolin particle film in South African orchards

Sunburn on apples in the Western Cape region of South Africa can result in yield losses of up to 50%. Application of kaolin-based particle film (Surround^® WP) increases leaf and fruit surface reflectivity, thus potentially reducing heat load and sunburn. Trials were performed during 2002/2003 and 2003/2004 to assess the effectiveness of kaolin particle film in controlling sunburn on ‘Granny Smith’, ‘Braeburn’, ‘Fuji’, ‘Royal Gala’ and ‘Cripps’ Pink’ apples. Fruit quality and ripening were monitored following 1–4 months in regular atmosphere cold storage at −0.5 °C. Sunburn on exposed fruit was significantly reduced in ‘Granny Smith’ and ‘Fuji’. Kaolin treatment improved fruit colour of ‘Granny Smith’ and ‘Royal Gala’, and delayed starch conversion in ‘Granny Smith’ at harvest and during the early storage period but not thereafter. Incidence of watercore at harvest was significantly reduced by kaolin treatment, but this disorder disappeared during cold storage in both treatments. There were no effects on skin anthocyanin or phenolic concentrations in any cultivar compared to unsprayed fruit.     

Pre- and post-harvest salicylic acid treatments alleviate internal browning and maintain quality of winter pineapple fruit

The post-harvest internal browning (IB) and quality in pineapple (Ananas comosus L. ‘Comte de Paris’) fruit were studied in relation to pre-harvest salicylic acid (SA) spray (PSS) or/and post-harvest salicylic acid immersion (PSI) treatments at 10 °C for up to 20 days plus 2 days at 20 °C (shelf-life). In addition, the activities of polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) were measured during cold storage. The results showed that all SA treatments significantly reduced IB incidence and intensity. Furthermore, SA did not affect soluble solids content (SSC), titratable acidity (TA) and total phenolics (TP) content, but delayed the decline of ascorbic acid (AsA) content. At the same time, SA significantly inhibited PPO and PAL activities. The study indicated the beneficial effect of SA by pre-harvest spray and/or post-harvest immersion on pineapple fruit quality and resistance to IB, and PSS + PSI treatment showed the best effect.     

5-Aminolevulinc acid increases tree yield and improves fruit quality of ‘Rabia’ and ‘Sukkariat-Yanbo’ date palm cultivars under hot arid climate

Date palms growing in hot arid regions are generally facing several kinds of environmental stresses which limit tree growth and productivity and negatively affect fruit quality. During 2009 and 2010 seasons, the effects of 5-aminolevulininc acid (5-ALA) application at different rates on yield, fruit quality, pigment contents and nutrient uptake of ‘Rabia’ and ‘Sukkariat-Yanbo’ date palm cultivars were studied. In both cultivars, the application of 5-ALA significantly increased bunch weight and yield per tree compared to control. The highest bunch weight and yield per tree was achieved by 5-ALA at 200 ppm followed by 250 ppm applied on both fruit bunches and leaves. These were reflected on higher fruit and flesh weight and fruit length, at the bisir and rutab stages. However, the application of 5-ALA at 250 ppm only on fruit bunches without leaves significantly increased bunch weight and yield per tree compared to control only in ‘Sukkariat-Yanbo’ but not in ‘Rabia’ cultivar. There were significant interaction effects between treatments and seasons on bunch weight and yield in ‘Rabia’ but not in ‘Sukkariat-Yanbo’ cultivar. The rutab % was not significantly affected by any of the applied treatments and it was higher in 2009 than in 2010 season in ‘Rabia’, however, the opposite was true in ‘Sukkariat-Yanbo’ cultivar. Most of the physical parameters of fruit quality at both the bisir and rutab stages were significantly improved in both cultivars by 5-ALA application compared to control, in contrast to the biochemical parameters that were not affected. In both cultivars, chlorophyll a concentration significantly increased by 5-ALA application especially at 200 and 250 ppm on both leaves and fruits compared to control. While chlorophyll b concentration was not significantly affected by the 5-ALA application, total chlorophyll concentration was significantly higher at 250 ppm 5-ALA application than control in both cultivars. There were no significant differences among the different rates of 5-ALA application. Chlorophyll a/b ratio was not significantly affected by 5-ALA application compared to control. The concentrations of N, P and K in the leaves of both cultivars were not significantly affected by the 5-ALA application compared to control. It was concluded that 5-ALA application has promotive effects on yield, fruit quality and chlorophyll concentration of both ‘Rabia’ and ‘Sukkariat-Yanbo’ date palms under hot arid climate.     

Effect of organic treatments with calcium carbonate and bio-activator on quality of ‘Reinette’ apple cultivars

‘Reinette du Canada’ (RC) and ‘Reinette Grise du Canada’ (RG) apple (Malus × domestica Borkh) cultivars declared throughout the Community as Protected Designation of Origin ‘Manzana Reineta del Bierzo’ are severely affected by bitter-pit during storage. Pre-harvest treatments with calcium carbonate, authorized in organic production, and bio-activator Harpin protein were used to assess the effect on quality at harvest and during cold storage in both apple cultivars during 2007 and 2008. Bitter-pit at the end of storage was higher in ‘RC’ than in ‘RG’, due to the fact that K/Ca ratio in fruit was higher in ‘RC’. Harpin protein did not improve the quality of ‘Reinette’ apple cultivars. Calcium carbonate pre-harvest treatments were useful to decrease external and internal bitter-pit incidence of ‘Reinette’ apple cultivars after 90 days of storage, but differences at the end of storage were not significant. Therefore, calcium carbonate would be a useful product in organic production in order to decrease bitter-pit incidence in ‘Reinette’ apple cultivars during medium term storage.     

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.     

Yield performance,quality characteristics and fruit storability of winter squash cultivars in sub-humid areas

This research investigated the quality traits of eight winter squash cultivars (Cucurbita maxima, C. moschata, C. pepo and interspecific hybrids of C. moschata × C. pepo) during three years, but only ‘Tetsukabuto’ and ‘Violina’ were tested each year. In 2005 these two varieties were compared to ‘Butternut’; in 2006 to ‘Red Kury’, ‘Tan Cheese’ and ‘Kabosha’; in 2007 to ‘Red Kury’, ‘Mooregold’, and ‘Winter Luxury’. The characteristics recorded were: fruit yield, storage ability, chemical composition and sensory quality. Following harvest and sorting of marketable winter squash, 50 fruits for each cultivar were stored at 12 °C for 12 weeks the 1st year, and for over 20 weeks in 2nd and 3rd years, during which rotten fruits were counted. Compositional analyses regarding sugar concentration, starch, carotenoids and dry matter content at harvest and after storage were carried out; a panel test was organised to assess sensory traits. The most interesting cultivars were ‘Tetsukabuto’ for yield, ‘Tetsukabuto’ and ‘Mooregold’ for storability, ‘Red Kury’ and the same ‘Tetsukabuto’ particularly for soluble sugars and carotenoids and sensory appreciation.     

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.     

Potential of ethephon,NAA, NAD and urea for thinning pistachio fruitlets

Alternate bearing, the occurrence of high yield ‘on’ year followed by low yield ‘off’ year, is striking in pistachio (Pistacia vera L.). Floral buds of pistachio are formed a year before bloom, but abscise during the years with heavy crop (‘on’ year). Abscission of floral buds is due to competition between growing seeds on 1-year-old shoots and developing buds on current season growth. We studied the effects of chemical fruit thinning on alternate bearing and nut characteristics in a commercial orchard of ‘Owhadi’ pistachio cultivar during 2003–2004 in Rafsanjan, Iran. In both years, ethephon (100 and 200 mg l⁻¹), naphthaleneacetic acid (NAA) (125 and 250 mg l⁻¹) and urea (2.5 and 5%) were applied to the branch units of each individual ‘on’-year trees. The results showed that ethephon at both concentrations significantly increased fruit thinning and floral bud retention for the subsequent year. Other treatments also increased fruit thinning and floral bud retention but were inferior to ethephon.     

Changes of physicochemical quality,phenolics and vitamin C content in hardy kiwifruit (Actinidia arguta and its hybrid) during storage

The effect of storage and the stage of maturity of hardy kiwifruits on the physicochemical quality, phenolics (TPC) and ascorbic acid content (AAC), as well as antioxidant activity (AA) were studied in this work. The phenolic compounds in hardy kiwifruits were separated and characterized by HPLC. The investigation was carried out on the two cultivars of Actinidia arguta – ‘Weiki’, ‘74-49’ and the hybrid of A. arguta and Actinidia purpurea (‘D14’). Fruit firmness rapidly decreased and the soluble solid content (SSC) increased for all cultivars during the first 14 days of storage at 1 °C. The AAC and TPC in vine ripe fruits were similar to the ones of the fruits of storage harvest maturity (8–10% SSC). AA content depended on the clone and either decreased during storage or remained almost unchanged. There was an increase in TPC after 7 days of keeping the fruits in a cold store chamber at the temperature 1 °C, but a longer period of storage caused a decrease in these compounds. AA (at harvest for storage purposes) was higher than that of vine ripe fruits and the ability to absorb free radicals slightly decreased during storage. There was a strong correlation between AAC, TPC and AA. That means that phenolics and vitamin C affect the antioxidant activity of hardy kiwifruits.     

Pineapple organic acid metabolism and accumulation during fruit development

Developmental changes in pineapple (Ananas Comosus (L.) Merrill) fruit acidity was determined for a ‘Smooth Cayenne’ high acid clone PRI#36-21 and a low acid clone PRI#63-555. The high acid clone gradually increased in fruit acidity from 1.4 meq/100 ml 6 weeks from flowering, and peaked a week before harvest at ca 10 meq/100 ml. In contrast, the low acid clone increased in acidity 6 to 8 weeks after flowering, peaked 15 weeks after flowering at ca. 9 meq per/100 ml and then sharply declined in 2 weeks to 6 meq/100 ml. The increased in total soluble solids (TSS) of the low acid clone began 6 weeks after flowering and for the high acid clone at 12 weeks after flowering. The increase in titratable fruit acidity (TA) paralleled the changes in the citric acid content of both clones. Citric acid content increased from less than 1 mg/g at 6 weeks after flowering to 6 to 7 mg/g, 9 weeks later. The malic acid concentration in both clones varied between 3 and 5 mg/g and showed no marked changes just before harvest. The developmental changes in fruit potassium were significantly correlated with fruit acidity and fruit total soluble solids in both the high and low acid clones. Developmental changes in acid-related enzymatic activities showed an increase in citrate synthase (EC 4.1.3.7) activity that occurred a week before harvest, coincided with the peak in citric acid in the high acid clone. An increase in aconitase (ACO, EC 4.2.1.3) activity was observed just before harvest as the decline in acidity occurred in the low acid clone. The activities of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31), malate dehydrogenase (MDH, EC 1.1.1.37) and malic enzyme (ME, EC 1.1.1.40) did not parallel any changes in fruit acidity. The results indicated that the change in pineapple fruit acidity during development was due to changes in citric acid content. The major difference in acid accumulation occurred in the low acid clone just before harvest when acidity declined by one-third. The activities of citrate synthase and aconitase possibly played a major role in pineapple fruit acidity changes.     

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.     

Partial rootzone drying maintains fruit quality of ‘Golden Delicious’ apples at harvest and postharvest

Partial rootzone drying (PRD) has been evaluated at harvest, but its effects on apple fruit postharvest life is little known for apples grown in semi-arid regions. The objective of this study was to test the hypothesis that water savings via PRD may affect fruit quality at harvest and postharvest-life of ‘Golden Delicious’ apples grown in a semi-arid region. The experiment was conducted from 2005 to 2007. The irrigation treatments were commercial irrigation as control (CI) and PRD. After 3 years of evaluation, fruit quality at harvest, measured as fruit weight, flesh firmness, and total soluble solids concentration, was similar between CI fruit and PRD fruit. Dry matter concentration (DMC) was higher in PRD fruit than in CI fruit in 2005. The fruit quality after 18 days storage at room temperature (13–18 °C and 51–56% relative humidity) was similar between CI fruit and PRD fruit. The DMC was the highest in PRD fruit in the 2005 and 2007 growing seasons, and tended to be higher in PRD fruit than in CI fruit in 2006. Total soluble solids concentration was ≈8.7% higher in PRD fruit than in CI fruit in 2007. Fruit weight loss was similar between treatments. This study suggests that water deficit via PRD did not damage fruit quality at harvest or after storage at room temperature. Additionally, PRD irrigation saved about 3240 m³ of water per hectare. Therefore, PRD can be recommended for commercial use in semi-arid regions and to those growers interested in either long-term storage or distant markets.     

Effect of synthetic auxins on fruit size of five cultivars of Japanese plum (Prunus salicina Lindl.)

Most of the Japanese plum (Prunus salicina) cultivars grown in Israel produce relatively small fruit. Application of 2 l solution tree⁻¹ of 25 mg l⁻¹ 2,4-dichlorophenoxypropionic acid (2,4-DP) as butoxyethyl ester (Power™), 15 mg l⁻¹ 3,5,6-trichloro-2-pyridyloxyacetic acid (3,5,6-TPA) as free acid (Maxim^®), or 25 mg l⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) + 30 mg l⁻¹ naphthaleneacetic acid (NAA) (0.3% Amigo™) at the beginning of pit-hardening, when fruitlet diameter was ca. 22 mm, caused an appreciable and significant increase in fruit size. The yield of large fruit per cv.: ‘Kesselmen’ (100% increase), ‘Songold’ (100%), ‘Black Diamond’ (800%), ‘Royal Diamond’ (160%) and ‘Royal Zee’ (100%). As a result, the total yield of all five cultivars was also increased dramatically. Anatomical studies with ‘Songold’ revealed that the main effect of these synthetic auxins was via direct stimulation of fruit cell enlargement. The above auxins had no negative effect either on fruit quality at harvest (and after 1 week in shelf-life), or on return yield in the following year.     

Combinations of GA3 and AVG delay fruit maturation,increase fruit size and improve storage life of `Feicheng' peaches

Summary

Different concentrations of aminoethoxyvinylglycine (AVG) and gibberellic acid (GA₃) and their combinations, applied at two stages of fruit growth, were evaluated for prolonging the marketing season of `Feicheng' peaches. GA<sub>3</sub> applied at the end of pit hardening, or AVG applied two weeks before commercial harvest, inhibited fruit maturation on the tree, delayed harvest and reduced flesh browning after cold storage in a concentration-dependent manner. A synergistic effect was found when both GA<sub>3</sub> and AVG were used, with the combination of 100 or 150.mg l<sup>±1</sup> GA<sub>3</sub>, applied at the end of pit hardening, and 100 mg l<sup>±1</sup> AVG, applied two weeks before harvest giving the best results. These combinations retarded the change in ground colour, loss of firmness, and reduction in acidity by 2±3 weeks. Since harvest was prolonged by 2±3 weeks, soluble solids content (SSC) in fruit increased compared with the control (harvested earlier). Fruit size was significantly greater on treated trees compared with the controls when fruit set was controlled to the same level by hand thinning. After four weeks of storage and 4.d at 208C, 83% of control fruit developed tissue browning, but only 5% of AVG + GA<sub>3</sub>-treated fruit developed browning after six weeks of storage and 4 d at 208C. Thus, the marketing season of `Feicheng' peaches was prolonged by at least four weeks by 100 or 150 mg l^±1 of GA₃ and 100 mg l^±1 of AVG. Fruit treated with 150 mg l^±1 GA₃ plus 100 to 150 mg l^±1 AVG showed similar results but failed to ripen properly after cold storage.