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.     

The influence of exposure to light on the phenolic content of ‘Fuji’ apple

In this study, the influence of changes in fruit lighting on individual and total phenols in ‘Fuji’ apple, as well as color development was studied. Content levels of eight quercetin glycosides, five anthocyanins, two catechins and a hydroxycinnamic acid in the skin of apples were analyzed, using high-performance liquid chromatography, tandem mass spectrometry (HPLC-MS). Total phenol, chlorophyll and carotenoid contents were determined by spectrometry. The purpose of this study was to compare content levels of those compounds in apple skin of fruit grown in different parts of the tree canopy, under and outside of the hail net. Lighting of fruit was measured during the last month before harvest. The lowest values were measured in the inner fruit and higher ones in the outer parts of the canopy, while the highest values were measured in fruit growing at the top of the tree. The hail net had no influence on the decrease of lighting in comparison to the control. Light conditions in the tree canopy influenced lower content levels of quercetin glycosides and most anthocyanins in the fruit skin in the inner part of the tree canopy, whereas fruit from the canopy top contained the highest levels of quercetin glycosides and cyanidin glycosides. Catechin, epicatechin and chlorogenic acid content levels in apple skin were independent of fruit position in the canopy or hail net usage, except for chlorogenic acid, where the content level was higher in cases when the orchard was covered with a hail net. Fruit from the top and outer parts of the canopy had a darker and redder coloration than inner fruit, while no influence of canopy position on chlorophyll and carotenoids was detected. Since quercetin glycosides and cyanidin glycosides are influential in red skin color development, better coloration of fruit from the outer and top canopy was observed. More intensive lighting stimulated a higher content level of flavonoids and, consequently, better coloration, which is an important factor in fruit quality.     

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.     

Effect of distance from early flowering pollinizers ‘Maypole’ and ‘Dolgo’ on ‘Fiji’ fruit set

An apple orchard consisting of a single cultivar under the condition of natural pollination must have suitable pollinizers such as Crab apples to ensure stable fruit production. We selected ‘Maypole’ and ‘Dolgo’ as pollinizers for the cultivar ‘Fuji’, and investigated the rate of fruit and seeds in ‘Fuji’ fruits produced by pollen of the pollinizers. We developed a method for tracing pollen flow based on the leaf color of progeny and S-RNase allele of ‘Maypole’, and on Simple Sequence Repeat (SSR) analyses of ‘Maypole’ and ‘Dolgo’. These were powerful tools for determining the distance insects (mainly Osmia cornifrons) carry pollen from the pollinizers to ‘Fuji’. Although the fruit set of ‘Fuji’ apples was not reduced with increasing distance between ‘Fuji’ apple trees and pollinizers (probably due to pollen flow from other commercial cultivars planted outside the area), the rate of ‘Fuji’ apple fruit produced by the pollen of the pollinizers decreased with increasing distance. The rate of fruit produced by the pollinizers was 84% and 77% when ‘Fuji’ was 2.5 m from ‘Maypole’ and ‘Dolgo’, respectively, and 71% and 64% when ‘Fuji’ was 5 m from ‘Maypole’ and ‘Dolgo’, respectively, but was reduced to 47% and 39% when ‘Fuji’ was 10 m from ‘Maypole’ and ‘Dolgo’, respectively. However, the spacing could cause reduced fruit size, and require extra fruit thinning for producing large fruits. It could also cause reduction of the yield for increasing the planting area of pollinizers. We recommend that pollinizers should be planted not more than 10 m from ‘Fuji’.     

Light penetration,growth, and fruit productivity in ‘Fuji’ apple trees trained to four growing systems

The study was conducted to document the range in soil nutrients, trunk and shoot growth, leaf characteristics and nutrient content, flower bud characteristics, yield, fruit quality, disease occurrence, light penetration, and shoot bark color in a 15-year-old ‘Fuji’ apple (Malus × domestica Borkh.) orchard on M.26 rootstocks trained to four growing systems. SS trees naturally growing had greater width and volume than the LT lightly heading, MLT heavily heading, and S trees thinning and bending. LT trees had more upward terminal shoots at old branches, large numbers of lateral shoots, and longer total shoot length. Leaf [N], [P], and [K] were the lowest for the MLT trees. SS and S trees had greater flower bud density and fruit yield, but LT trees had poor fruit color and less soluble solids and firmness. Percent light penetration into the canopy was the highest with the S system but not different from MLT or SS. The lowest was for the LT system, however, it was not statistically different from MLT or SS.     

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.     

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.     

Differential effect of cultivar and harvest date on nectarine colour,quality and consumer acceptance

The influence of nectarine cultivar and the harvest date on fruit colour, fruit size, fruit quality parameters, and consumer acceptance were assessed. The analyses were carried on cultivars with different fruit taste (acidity and sweetness), from 5-years-old trees at the IRTA-Experimental Station of Lleida (Spain). The six cultivars were grouped in three pairs in which each had a similar commercial harvest date. Each pair comprised by a non-acid cultivar and an acid cultivar, except the pair of ‘Big Top^®’ and ‘Mesembrine^®’, which included two non-acid cultivars. The nectarines were harvested at 8 days intervals on five harvest dates, three of which were before the commercial harvest date, one at commercial harvest and another 1 week after commercial harvest.     

Effect of high temperatures in the pre-blooming and blooming periods on ovule formation,pollen grains and yield of ‘Granada’ peach

The aim of this work was to evaluate the effects of high temperatures in the pre-blooming and blooming periods on the growth of sexual gametes and yield of ‘Granada’ peach. The experiment was carried out in the commercial orchard of Charqueadas, under the subtropical conditions of the Central Depression at Rio Grande do Sul State, Brazil (28°57′S; 51°37′W; 30 m alt.). Two treatments were tested: (1) trees in the greenhouse with partial ventilation and (2) trees in the orchard. The phenology, morphologic constitutions of the pollen grains, ovule growth, yield and germination (%) of pollen grains and fruit set were evaluated. High temperatures in the pre-blooming and blooming periods anticipated the break of dormancy and blooming. These conditions also delayed the female gametophytes (embryo sac) and promoted anomalies in the formation of male gametophytes. Those factors promoted low pollen viability and a lack of synchrony in fertilization, thereby generating low fruit set percentages and yield.     

Relation of peel damage in citrus fruit to wind climate in orchard and its control

Peel damage originated by wind is the main abiotic cause of citrus fruit discards for export in Uruguay. Natural windbreaks such as Eucalyptus and Casuarinas have not been effective in reducing it. This research was carried out during three years in a citrus orchard situated in the coastal plain of Uruguay (35° SL). The purpose of this work was to study wind climate inside the orchard, fruit seasonal sensitivity, basal leaf effect on the onset and evolution of peel damage, and the efficiency of artificial windbreaks to reduce fruit discard of ‘Ellendale’ tangor. Average wind velocity in the orchard did not exceed 5 m s⁻¹. First peel scars were evident two weeks after petal fall and damaged fruit percentage importantly increased during the first stage of fruit growth. Low energy vortexes caused almost permanent friction between basal leaves and the developing fruitlets growing in their axil. Removal of the basal leaf decreased significantly wind damaged fruit. Natural wind flow modification through the use of semi-porous artificial windbreak nets (5 cm by 10 cm mesh) modified low energy vortexes and increased significantly the percentage of export quality fruit. We conclude that this type of net is more efficient than natural windbreaks or classical nets to reduce wind damage in citrus fruit.     

Random sample estimates of tree mean for fruit size and colour in apple

Data obtained in 2005 from thinning experiments with ‘Ariane’ and ‘Pitchounette’ apples (Malus × domestica L. Borkh.) were used to estimate tree mean fruit diameter (MD), weight (MW) and proportion of red overcolour (MC) using random samples. Twenty fruit per tree were taken from the boxes containing the fruit harvested at each picking. To avoid taking only fruit in the upper layers of the boxes, fruit from each tree were spread out on a table beforehand. The estimated values were compared with the true MD, MW or MC calculated from each picking and from the entire crop. Statistical techniques were used to assess agreement between the values obtained with estimation methods and the true values. Estimates obtained from a sample averaging ∼15–20% of total crop may range from 2 to 3% of the true mean diameter, and from 6.0 to 8.5% of the true mean weight. Estimates for MC obtained from the same samples may range from 10 to 25% of the true mean overcolour. The error margin associated with estimating fruit diameter and weight from the sampling method employed in this study seems to be small enough to consider it reasonably adequate to detect treatment differences that would be considered biologically or economically significant. Blind sampling and colour determination through image analysis are suggested as a means to obtain unbiased and objective data for fruit colour determinations.     

Reflective materials under hailnet improve orchard light utilisation,fruit quality and particularly fruit colouration

The increase in hailstorms, possibly due to climate change, has led to installation of hailnets in fruit orchards worldwide. This is associated with poorer fruit quality, particularly fruit colouration, which is determined by the light conditions viz diminishing light intensities and shorter day length in the autumn. To overcome these adverse effects of hailnets, five materials were examined as possible ground covers as to their light reflection and the subsequent effect on fruit quality including fruit colouration, using a 9-year-old apple orchard cv. ‘Gala Mondial’ on M9 under black hailnet near Bonn. The ground covers included the woven white plastic Extenday^R/Daybright™, the kaolin-coated, bio-degradable paper UniSet O™ and the aluminium-coated plastic Mylar™ and Svensson ILS Alu™; the latter is a white plastic interwoven with aluminium strips used as energy saving screen in greenhouses. The ground covers were spread in the alleyways 4–5 weeks before anticipated harvest; adjacent uncovered grass strips under the hailnet served as control. Light reflection, measured perpendicular at 1 m height in the alleyways at the time of fruit colouration, was 79–80% by Extenday^R/Daybright™, 75% by UniSet O™, 68% by Mylar™ and 58% by Svensson Alu ILS™. Apple fruit with any of the reflective ground covers ripened 2–3 days earlier without affecting internal fruit quality and sugar as indicative of taste. The reflective ground covers under black hailnet improved the proportion of well-coloured class I fruit relative to the control (uncovered grass) by an averaged 9%. Economic analysis showed that Extenday^R, with an expected lifetime of ten years (based on 4–6 weeks spread time per year) under hail nets in North-Western Europe, scored best based on 45 t ha⁻¹ yield in cv. ‘Gala Mondial’ and 0.40 € kg⁻¹ farm-gate price, resulting in 200 € ha⁻¹ net return. Manual labour for spreading and retrieving the ground covers had the major share of the overall gross cost and offers scope for improvement by mechanisation.     

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.     

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).     

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.     

安哥诺李果皮花青苷与内源激素、酶活性变化规律及其相关性

为了明确李果实花青苷合成的调控因子,以安哥诺李为试材,对果皮花青苷、内源激素和PAL、PPO活性的变化以及内源激素、酶活性与花青苷的相关性进行研究。结果表明,果皮花青苷含量在发育前期含量很低,发育后期含量迅速升高,呈上升趋势;果皮中ABA、乙烯、ZT含量和PPO活性与花青苷的变化趋势相同,乙烯释放量与花青苷呈极显著正相关关系r=0．8885**,ABA和ZT含量与花青苷呈显著正相关关系r=0．7159*和r=0．7476*,PPO活性未达显著水平;果皮中IAA、GA3含量和PAL活性变化在发育前期含量较高,在发育后期含量较低,果实发育过程中IAA、GA3含量呈逐渐下降趋势,与花青苷呈显著负相关关系r=-0．7039*和r=-0．8238*,PAL活性未达显著水平。     

Effects of bagging on fruit development and quality in cross-winter off-season longan

Clusters of cross-winter off-season longan (Dimocarpus longan Lour) cv. Chuliang were bagged with three types of bags: perforated translucent plastic bag (TPB), white adhesive-bonded fabric bag (WAFB) with about 70% light transmittance, and black adhesive-bonded fabric bag (BAFB) with <10% light transmittance. Bagging treatments began at 34 days after anthesis and continued until harvest. The results showed that bagging modified the microenvironment for fruit development. Bagging with TPB was most effective in increasing humidity, and air moisture within TPB maintained above 90% from 2 weeks after bagging. Bagging with BAFB or WAFB increased humidity most of the time, and the effect was more prominent when the weather was very dry (RH < 60%). All bag types tended to increase temperature and promoted fruit development, resulting in larger sized fruit. Bagging tended to promote early fruit drop but reduced late fruit drop, and the final fruit retention rate was not significantly affected by bagging. Bagging with different materials showed differential effects on incidence of fruit cracking. WAFB and BAFB reduced cracking incidence significantly as compared to the control (5.1% and 11.6% vs 32.8%). Sugar content was not significantly affected by bagging but organic acids including vitamin C (Vc) were considerably affected. Concentration of malic acid, the dominant organic acid in longan aril, was 605.6, 830.0, 1161.0 and 1428 μg/g FW in TPB, BAFB, WAFB and the control. Vc in the aril was significantly reduced by BAFB (108.4 μg/g FW), slightly increased by WAFB (183.9 μg/g FW) and significantly increased by TPB (264.5 μg/g FW) as compared with the control (174.7 μg/g FW). Pericarp of fruit bagged with TPB had a slightly higher content of Vc (1337 μg/g FW), while those bagged with BAFB (873.6 μg/g FW) and WAFB (787.4 μg/g FW) had significantly lower Vc contents than the control (1243 μg/g FW). The responses of oxalate and Vc contents in the aril and the pericarp to bagging treatments showed an opposite trend. The results suggested that WAFB increased fruit size and fruit retention rate while significantly reduced fruit cracking incidence and could be a promising practice for cross-winter longan production.     

Fruiting position during development of ‘Nules Clementine’ mandarin affects the concentration of K,Mg and Ca in the flavedo

Adequate K, Mg and Ca supply is important to develop well-structured and functional cell walls and membranes in fruit, and insufficient levels or imbalances of these minerals are known to be involved in various postharvest disorders. Microclimatic variation exists in the ‘Nules Clementine’ mandarin tree canopy and results in lower photosynthetically active radiation (PAR) levels and temperature as well as a higher humidity inside the tree canopy. The aim of this experiment was to determine the impact of this variation in microclimate on accumulation patterns of K, Ca and Mg in the flavedo of the fruit rind during stages II and III of fruit development. Fruit mass, dimensions, rind colour development and mineral composition of the flavedo were measured to describe the condition of fruit borne on the outside and inside of the tree's canopy. The data revealed that canopy position influenced mineral nutrient accumulation patterns in the flavedo. Outside fruit flavedo accumulated significantly higher concentrations of Ca and Mg in all three seasons (2005–2007). In contrast, inside fruit flavedo (shaded fruit) accumulated significantly higher levels of K compared with outside fruit flavedo. The accumulation of K and Ca differed from that of kiwifruit and apple in that Ca concentration increased and K decreased towards maturity. These results suggest that xylem, as in citrus leaves, is the main vasculature supply conduit to the citrus fruit flavedo for mineral nutrients. The reduction of transpiration potential by lower temperatures and higher humidity inside the canopy could be responsible for the reduced accumulation of Ca and Mg. The high K concentration of inside fruit flavedo is suggested to be a stress response, due to the low light levels, to maintain osmotic potential in the shaded rind tissue, and this imbalance could possibly lead to a reduction in rind condition, which manifests through rind breakdown symptom development.     

Improved fruit retention,yield and fruit quality in mango with exogenous application of polyamines

Aqueous solutions (0, 0.01, 0.1, 1 mM) of PAs (putrescine, spermine, spermidine) containing a surfactant ‘Tween 20’ were sprayed onto panicles of mango (Mangifera indica L. cv. Kensington Pride) at final fruit set (FFS) stage (when all flowers abscised but remain attached to the panicle) during 1999–2001 to investigate their effects on fruit retention, yield, size, and fruit quality. The optimum time of PA application for improving final fruit retention and fruit yield was determined by spraying different concentrations (0, 0.01, 0.1, 1 mM) of spermine (SPM) containing a surfactant ‘Tween 20’ at four phenological stages including flower bud differentiation (FBD), 5–8 cm long grown panicles (GP), full bloom (FB) and at initial fruit set (IFS) stage (when 2/3rd of the flowers were abscised but attached to the panicle) during 2000. Exogenous application of PAs at FFS stage did not significantly increase fruit retention. However, compared to control (0.79 and 2.3% fruit retention), PAs treatments resulted in comparatively higher mean fruit retention (1.53 and 2.92%) during 1999–2000 and 2000–2001, respectively. Among three PAs tested, SPM was more effective in increasing mean final fruit retention. Fruit size was not significantly affected by any PA treatment. Among the four application times, SPM (0.01 mM) spray at FB stage resulted in significantly (P ≤ 0.05) greater fruit retention (4.99%) compared with control (2.1%). However, fruit yield was comparatively higher with SPM (0.01 mM) application at IFS stage or 5–8 cm GP stage compared to the control. Overall FB application was found as the optimum time of application. Application of PAs at FFS stage retarded fruit skin colour development compared to the control. Sugars and total soluble solids (TSS) were generally reduced in PA-treated fruit. Fruit acidity was increased (16.7%) with SPM, whereas it was 11% with PUT treatment as compared to the control. Total carotenoids in pulp were generally improved (49%) with PA treatments, compared to the control. Ascorbic acid concentrations were significantly reduced with spermidine (SPD) (24%) and PUT (20%) treatments, whereas higher concentrations of SPM (1 mM) tended to increase it (12.7%) compared to the control. In conclusion, application of SPM (0.01 mM) at FB stage resulted in the highest fruit retention, whereas SPM (0.01) spray at GP or IFS stage resulted in higher fruit yield. PUT application at FFS stage significantly improved fruit quality by increasing total carotenoid, while reducing acid content of ripe fruit.