Chemical composition of French and Polish cloudy apple juices

Summary

Cloudy juices from six apple cultivars from Poland (‘Ariwa’, ‘Gold Milenium’, ‘Florina’, ‘Melfree’, ‘Novamac’, and ‘Rajka’) and four French cultivars (‘Ariane’, ‘Chanteline’, ‘Judeline’, and ‘Judor’) were produced and chemically characterised. The analyses encompassed 23 chemical parameters and phenolics profiles. The most important parameter, differentiating cloudy juice from clear juice, was turbidity. Cloudy juices were characterised by having an average total turbidity of 1,210 Nephelometric Turbidity Units (NTU) and a stability of turbidity of 42%. Some of the results deviated from the accepted ranges given in reference values for apple juices in the Code of Practice of the European Fruit Juice Association. This occurred in the cases of simple sugars and saccharose contents of the Polish apple juices (e.g., up to 56.9 mg l^–1 of saccharose vs. a maximum value of 30 mg l^?1), and for some mineral compounds in the French apple juices (e.g., sodium values up to 10 mg l^?1). Large variations were found in case of important healthconferring components. Water-soluble pectin contents varied from 205 mg l^?1 for ‘Chanteline’, to 1,289 mg l^?1 for ‘Gold Milenium’; while, in the case of phenolic compounds, the range was from 85.7 mg l^?1 for ‘Novamac’, to 524.8 mg l^?1 for ‘Melfree’.     

Phenolic Compounds,Antioxidant Activity,Fatty Acids and Volatile Profiles of 18 Different Walnut (Juglans regia L.) Cultivars and Genotypes

The study was carried out to determine phenolic compounds, antioxidant activity, total lipids, saturated fatty acids, unsaturated fatty acids, and volatile organic compounds (VOCs) of 18 different walnut (Juglans regia L.) cultivars and genotypes grown in Usak province, Turkey. The biochemical compounds were identified for each cultivar and genotype and a comparative evaluation was carried out. The results showed that most of the biochemical compounds are significantly varying among each other (p?<?0.05). The existence and abundance of the biochemical compounds in the cultivars and genotypes have not only found to be a cause of differentiation, but they have been important parameters for the similarities among the cultivars and genotypes. Total phenolic content and antioxidant activity ranged from 750.67 to 1245.64?mg GAE ml^?1 and from 42.46 to 56.50% in kernels, respectively. The highest contents of the phenolic compounds were noted from gallic acid (11991?mg kg^?1), ellagic acid (1057.16?mg kg^?1), catechin (425.4?mg kg^?1), and rutin (216.6?mg kg^?1), as an average of all cultivars and genotypes. The highest lipid contents were noted from ‘Franquette’ and ‘Fernette’ as 64.28% and 63.26%, respectively, while the lowest content was noted from ‘Oguzlar 77’ (52.52%). A total of 42 VOCs were described from the 18 different walnut cultivars and genotypes. Overall, results showed that the phenolic profiles, fatty acids composition, and VOCs play an important role in similarities and diversities among the cultivars. According to the results, 7 different clusters were developed from the 18 cultivars and genotypes. Herein, ‘Fernor’, ‘Maras 18’, ‘Arslan Local Type’ and ‘Cisco’ cultivars were found to have the lowest biochemical compositions. The superior cultivars or genotypes, in terms of the abundance of the biochemical composition, were found to be ‘Gulizar Hanim Type’, ‘Lara’, ‘Pedro’, ‘Tulane’, ‘Fernette’, ‘Balkan’ and ‘Franquetta’, where they were found to develop 3 clusters by 1:3:3, respectively.

     

Studies on the Maturity of Apples.: Respiration Progress Curves for Cox’s Orange Pippin Apples for a Number of Consecutive Seasons

Summary

The effect of UV-B irradiation at 10°C and 20°C on the quercetin glycosides procyanidins, chlorogenic acid and anthocyanin levels in the skin of detached fruit of five apple cultivars was investigated. UV-B responsiveness was compared between sides of the fruit that were outwardly facing (exposed) and inwardly facing (shaded) when on the tree. There were no common effects of UV-B irradiation and temperature across all cultivars. UV-B irradiation increased the quercetin glycoside levels in the shaded side of ‘Gala’, ‘Royal Gala’ and ‘Braeburn’ fruit and only at 20°C. UV-B irradiation of the exposed sides of the five cultivars, of either side at 10°C, and of ‘Pacific Rose’ and ‘Aurora’ at either 10°C or 20°C had no significant effect on quercetin glycoside levels. There was no effect of UV-B irradiation on procyanidin levels at any combination of treatments. However, levels of chlorogenic acid, although one tenth of those of quercetin glycosides and procyanidins, increased markedly with UV-B irradiation. Both exposed and shaded sides of fruit of all cultivars increased in chlorogenic acid levels at 10°C and 20°C after UV-B irradiation. UV-B irradiation increased anthocyanin levels in exposed and shaded sides of fruit of all cultivars at 20°C, and on ‘Braeburn’, and ‘Aurora’ at both 20°C and 10°C. UV-B irradiation at either temperature had no significant effect on either the relative proportions of the glycosides of quercetin (galactoside, rhamnoglucoside, glucoside, xyloside, arabinoside and rhamnoside) or the relative proportions of the procyanidins (Procyanidins B2, B5, epicatechin and catechin). The effect of UV-B irradiation was variable, depending on cultivar, previous light exposure, temperature and class of flavonoids examined.     

Composition and properties of purified phenolics preparations obtained from an extract of industrial blackcurrant (Ribes nigrum L.) pomace

Summary

An extract obtained from industrial blackcurrant pomace was purified and fractionated on an RP C18 column, resulting in three phenolics preparations of different composition. The phenolics in the preparations were quantified by HPLC, their anti-oxidant capacity was determined, and the preparations were subjected to HPLC-MS analysis in order to identify the bioactive compounds present. The purified preparations selected for study were an anthocyanin-rich preparation, a myricetin and quercetin glycosides-containing preparation, and an aglycon-containing preparation. All three preparations were characterised by having a high content of polyphenols. The anthocyanin-rich preparation was the most concentrated in polyphenols [> 50% (w/w)], followed by the aglycon-containing preparation [> 20% (w/w)], and finally the glycosides-containing preparation [> 9% (w/w)]. The preparations were also characterised by their high anti-oxidant capacity, which was > 3,100 µM TEAC g^?1 (TEAC = Trolox Equivalent Anti-oxidant Capacity) for all preparations. The HPLC-MS study confirmed that the anthocyanin-rich preparation was composed of the following anthocyanins: delphinidin-3-glucoside, delphinidin-3-rutinoside, cyanidin-3-glucoside, and cyanidin-3-rutinoside. The aglycon preparation contained four aglycons, of which myricetin and quercetin were predominant, and kaempferol and isorhamnetin were present in lower amounts. The glycosides-containing preparation was found to be the most interesting, since it contained myricetin, quercetin, kaempferol, and isorhamnetin glycosides. Myricetin and quercetin galactosides were also detected in blackcurrant extract for the first time. Moreover, the presence of nitrile-containing compounds, two acylated anthocyanins, and one auron-type compound was detected.     

Determination of Energy Use Efficiency of some Apple (<Emphasis Type="Italic">Malus x domestica</Emphasis>) Production in Turkey: a Case Study of Eğirdir Region

This research aims to make an analysis of energy use efficiency of apple (‘Starkrimson Delicious’ and ‘Golden Delicious’) production in E?irdir region of Turkey, during the production season of 2012. Production data this research was collected in 2013. In order to determine the energy use efficiency of apple, various surveys have been conducted in 71 apple farms, selected through Simple Random Sampling method, located in E?irdir region of Turkey. The data have been collected through face to face questionnaires and first hand observations. The energy input and output values in apple production have been calculated as 34,703.63 MJ ha^?1 and 95,034 MJ ha^?1, respectively. Energy inputs consist of diesel fuel energy by 29.04?%, chemical fertilizers energy by 24.28?%, machinery energy by 15.70?%, chemical energy by 9.84?%, human labor energy by 8.54?%, electricity energy by 5.63?%, irrigation energy by 3.97?%, farmyard manure energy by 2.88?% and lime energy by 0.12?%. Energy use efficiency, energy productivity, specific energy and net energy in apple production have been calculated as 2.74, 1.16 kg MJ^?1, 0.86 MJ kg^?1 and 60,330.36 MJ ha^?1, respectively. The total energy input consumed has been classified as direct, by 47.17?%, indirect, by 52.83?%, renewable, by 15.38?% and non-renewable, by 74.62?%.     

Efficacy of Natureseal® AS1 browning inhibitor in fresh-cut fruit salads applications,with emphasis on apple wedges

Summary

Prevention of browning in fresh-cut fruit is of major commercial significance as fresh-cut fruit salads are major players in the international marketplace. Natureseal^® AS1 and AS5 browning inhibitors out-performed ascorbic acid and citric acid in tests with fresh-cut wedges of ‘Bramley’ apple. A dipping regime of 2 min in 6% (w/v) AS1 solution was found to be optimal, as longer dip-times and higher concentrations led to significant residues of AS1 on the fresh-cut ‘Bramley’ wedges. Tests on fresh-cut wedges from ten apple cultivars indicated that AS1 was significantly beneficial (P < 0.001) to maintain wedge colour during chill-storage in all cultivars, with the exception of ‘Shampion’, which had a low browning tendency and performed equally well with or without AS1. Tests on the anti-oxidant status of a generic fruit salad, which was not treated with AS1 and stored for 15 d, indicated a significant reduction in anti-oxidant status, due largely to the depletion of vitamin C (from 137 to 97 mg 100 g^?1 DW). Total phenolics contents remained relatively constant over the 15-d storage period. The outcomes from these trials have been presented to commercial food companies with a view to their uptake.     

1-Naphthaleneacetic acid and 6-benzyladenine thinning of a common slender spindle ‘Jonagold’/M.9 apple orchard. I: Dose effects and spray distribution in the crowns

Summary

To find the most appropriate rates of application of plant growth regulator (PGR) thinning-agents for a common slender spindle apple (Malus × domestica Borkh.) orchard, different volumes of dilute 1-naphthaleneacetic acid (NAA) and 6-benzyladenine (BA) were sprayed ha^?1. Mature ‘Jonagold’/M.9 trees, 3.0 – 3.5 m high and 1.2 – 1.5 m wide, planted in a single row system with 3,030 trees ha^?1, were used. Significant thinning was observed in the case of dilute sprays of NAA at 10 mg l^?1, or BA at 100 mg l^?1, to run-off, using 2,000 l ha^?1 or 1,500 l ha^?1; while 1,000 l ha^?1 did not result in sufficient thinning. Thinning using smaller volumes (250, 500, or 750 l ha^?1) was also significant if the concentration of PGR thinner was proportionally higher (i.e., based on the 1,500 l ha^?1 application rate of more dilute sprays of NAA at 10 mg l^?1 or BA at 100 mg l^?1). Spray distribution measurements in the crowns showed better spray deposits when higher water volumes (i.e., more dilute PGR solutions) were sprayed at all positions (bottom, middle, or top) of the canopy. At 2,000 l ha^?1, 54 – 72% coverage of the leaf area was observed; but, at 250 l ha^?1, coverage was only 10 – 21%. The lower 30% of the canopy was covered poorly when smaller volumes of water (250, 500, or 1,000 l ha^?1) were applied. When 1,500 l ha^?1 was sprayed, good coverage of the lower and upper surfaces of the leaves occurred, and no differences in canopy positions were measured. It was concluded that 1,500 l ha^?1 (i.e., dilute PGR) spraying was the most appropriate volume to use when calculating the dose of NAA or BA to be applied ha^?1 to common (3.0 – 3.5 m-high) mature slender spindle apple orchards on M.9 rootstock. This study was part of the ISAFRUIT Smartfruit Project, aimed at improving existing methods for apple crop regulation with more precise use of PGR thinning agents and with minimum impact on the environment.     

Responses of day-neutral,June-bearing and everbearing strawberry cultiv ars to gibberellic acid and phthalimide treatments

Field grown day-neutral, June-bearing and everbearing strawberry cultivars responded similarly to GA₃ in most cases. GA₃ stimulated daughter-plant production in ‘Hecker’ (DN) and suppressed it in ‘Guardian’ (June). Fifty mg l^?1 GA₃ increased initial runner production of all cultivars, while both 50 and 100 mg l^?1 GA₃ increased fruit yield the year following treatment. In greenhouse studies, GA₃ initially increased leaf number, petiole length and runner production, but the effects diminished with time. Phthalimide at 1000 mg l^?1 was most effective in increasing leaf number.     

The Growth of Apple Central Fruits as Affected by Thinning with NAA,BA and Naphthenic Acids

Plant growth regulators such as α?naphthylacetic acid (NAA) or 6?benzyladenine (BA) are commonly used for thinning apple fruits. NAs exhibits an auxin- and gibberellin-type biological activity, stimulate the uptake and translocation of auxins in plant tissue, as well as IAA synthesis and act as surfactants. It was assumed that NAs applied at the stadium of early fruit growth might cause fruit abscission in apple, similarly to NAA. The goal of the research was to test the presumed thinning effect of naphthenic acids on apple cultivars ‘Golden Delicious’ and ‘Red Delicious’. Three treatments were applied on both apple cultivars including 16.5?μL L^?1 NAA, 200?μL L^?1?BA and 2.63?mg L^?1?potassium salts of NAs. Cortical cell size and the number of cell layers were measured in order to determine the contribution of cell size and cell division in early fruit growth, as affected by chemical thinning treatments. The effects of plant growth regulators NAA, BA and NAs on fruit set, fruit size and the anatomy of the fruit cortex highly depend on varietal differences. In ‘Golden Delicious’ fruit set reduction by chemical thinning increases both the number of cell layers and cell size of apple fruit, while in ‘Red Delicious’ NAA inhibits fruit growth, while BA is ineffective. Cell growth promoting activity of NAA and NAs, accompanied by the decrease in fruit set and reduced competition among fruits within the canopy, results in a significant fruit weight increase at harvest. The research confirms the auxinic properties of NAs, and their assumed thinning activity.     

Factors affecting the efficacy of agar-based substrates for the study of tomato pollen germination

Summary

The present work examines the effects of substrate additions and incubation conditions on in vitro germination of tomato pollen on semi-solid, agar-based substrates with the ultimate aim of defining a standard semi-solid substrate for tomato pollen germination studies. Partial replacement of sucrose by polyethylene glycol (PEG-6000) for osmotic regulation of the substrate significantly increased pollen germination of both the low temperature-susceptible F₁ cultivar ‘Dombito’, and the more temperature-resistant cv.‘Supermarmande’, to a level that varied according to the season of pollen harvest. In contrast, partial substitution of sucrose by mannitol was inhibitory to an extent that depended on the final concentration of mannitol in the medium. The optimum pH for germination was 6.5 and the optimum incubation temperature was 15°C. Among the vitamins (riboflavin, thiamine, pyridoxine, niacin, pantothenic acid, p-aminobenzoic acid), amino acids (glutamic acid, aspartic acid), casein hydrolysate, plant growth regulators (gibberellic acid, indole-3-acetic acid, indole-3-butyric acid, indole-3-propionic acid, 1-naphthaleneacetic acid, kinetin) and flavonoids (naringin, myricetin, naringenin, quercetin, rutin) tested, a significant increase in pollen germination was induced only by the flavonoids quercetin and myricetin and, to a lesser extent, by indole-3-acetic acid. In contrast, both kinetin and naringenin were inhibitory, as were both amino acids at 100 mg l^–1 and casein hydrolysate (at 1.0 – 10.0 g l^–1). On the basis of the above results, we conclude that, for both tomato cultivars tested, the most suitable semi-solid substrate among those examined was that containing 10% (w/v) sucrose, 15.1% (w/v) PEG-6000 and 1.5% (w/v) agar, with the possible addition of 5 mg l^–1 quercetin, or 5 mg l^–1 myricetin.     

Influence of growth regulators on setting,retention and weight of fruits in two cultivars of litchi

Investigations were undertaken to explore the possibility of improving setting, retention and weight of fruits in ‘Early Seedless’ and ‘Calcuttia’ cultivars of lichi (Litchi chinensis) by means of growth regulators. Indole acetic acid (IAA) at 20, 40 and 80 mg l^?1, 2,4-dichlorophenoxy acetic acid (2,4-D) at 2,4 and 8 mg l^?1 and gibberellic acid (GA₃) at 50, 100 and 150 mg l^?1 were sprayed on panicles in the first fortnight of April, when 50–100% flowers had opened. All 3 growth regulators caused a favourable effect on fruit setting, fruit retention and weight of individual fruits, but IAA at 20 mg l^?1 proved the best for enhancing setting, GA₃ at 50 mg l^?1 for increasing retention and GA₃ at 100 mg l^?1 for improving fruit weight. IAA and GA₃ should, therefore, be used in combination. Between the 2 cultivars tested, ‘Calcuttia’ proved superior to ‘Early Seedless’ in fruit setting, fruit retention and weight of individual fruits.     

Calcium deficiency of ‘Cox's Orange’ apple trees during the fruit growth period

In a pot experiment with apple trees, cultivar ‘Cox's Orange’, Ca was omitted in the nutrient solution for periods of different length. Trees lacking Ca in the latest $\text{2}\text{3}$ of the growth period contained 42 mg kg^?1 Ca in the fruits, which is 21% below control. In the bulked sample, average size of fruits was not considerably affected, but the distribution of small and large fruits changed toward more smaller fruits. Concommitantly, bitter pit was reduced compared to the control.Sufficient K supply (1.20–1.70% K in leaf dry matter) given to trees receiving high Ca supply depressed Ca concentration in the fruits to 41 mg kg^?1, which is 23% below control. Average fruit size was not significantly changed, but the distribution was towards larger fruits. Under these circumstances bitter pit was increased. Ca deficiency, caused either by omission of Ca or competition between K and Ca, increased fruit rot, russeting and cracks on the fruits. Short term variations in Ca levels were not seen to produce any measurable response.     

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.     

The King Fruit versus Lateral Fruit Thinning Effects on Yield and Fruit Quality in Apple

ABSTRACT

This research was conducted to determine the king versus lateral fruit thinning effects on yield and fruit quality of ‘Elstar’, ‘Granny Smith’, ‘Starkrimson Delicious’, ‘Ultra Red’, ‘Topred’, and ‘Jonagold’ apple (Malus domestica Borkh.) cultivars grafted on MM106 rootstock in 2002-2003. Removal of the king fruit (KFR) treatment partially increased the yield in ‘Jonagold’, ‘Elstar’, and ‘Granny Smith’ cultivars while the effects were different by years in “Starkrimson Delicious”. Leaving of the king fruit (KFL) treatment gave better results in the ‘Topred’ cultivar, and similar effects were obtained from both treatments in ‘Ultra Red’ cultivar. Non-significant differences were obtained from both treatments with respect to fruit weight in the ‘Topred’, ‘Starkrimson Delicious’, ‘Jonagold’ and ‘Granny Smith’ cultivars. Leaving of the king fruit treatment increased the fruit weight significantly in ‘Elstar’ and ‘Ultra Red’ cultivars in 2002. The values of fruit flesh firmness (lb), total soluble solids content (%), pH, titratable acidity (%), total and invert sugar quantity (g/100 g^?1) were not found to be significantly different between the treatments with a few exceptions. The ‘KFR’ treatment that removed the dominant effect of the king fruit can be recommended for the ‘Elstar’ and ‘Jonagold’ cultivars because this treatment increased the yield and did not decreased the fruit weight significantly in these cultivars except for ‘Elstar’ in 2002. On the other hand ‘KFL’ treatment can be recommended for the ‘Granny Smith’, Topred’ and ‘Ultra Red’ cultivars. Although this treatment decreased the yield of ‘Granny Smith’ it increased the mean fruit weight 45.6-62.7 g in the two experiment years. ‘Starkrimson Delicious’ did not show clear response to the treatments.     

Influence of different disease control pesticide strategies on multiple pesticide residue levels in apple

Summary

Seven pesticide application strategies were investigated to control apple scab (Venturia inaequalis) and powdery mildew (Podosphaera leucotricha) and, at the same time, fulfil the new quality standards implemented by some German retailers. These demand that pesticide residues should be below 80% of European Maximum Residue Levels (EU MRL) and that the number of residues present at levels above 0.01 mg kg^?1 should be limited to a maximum of four. The strategies fulfilled the requirement to use combinations of different active substances in order to prevent the emergence of resistance to pesticides. The trials were conducted at two sites in Switzerland, in 2007, and all strategies and applications were in accordance with actual practice. Four replicates of apple samples from each strategy were then analysed for pesticide residues. The incidence of infection with apple scab and powdery mildew were monitored during the season in order to evaluate the efficacy of the different strategies. The efficacies of the different strategies against apple scab and powdery mildew were between 84% and 100% successful. In general, the level of pesticide residues found correlated with application rate and time, and no measured residue level exceeded the EU–MRL. The numbers of residues present at > 0.01 mg kg^?1 were between two and five.     

In vitro somatic embryogenesis from Mangifera indica L. callus

The nucellus and globular adventitious proembryos were removed from 2-month-old fruits of mango (Mangifera indica L.) cultivars ‘Ono’ and ‘Chino’, and were cultured on sterile, solid Murashige and Skoog (MS) medium that had been modified as follows: half-strength major salts and chelated iron; 20% (v/v) coconut water (CW); 6% sucrose; 100 mg l^?1 ascorbic acid and 400 mg l^?1 glutamine. Embryogenic explants were sub-cultured after 4–6 weeks in liquid modified MS medium containing 2 mg l^?1 2,4-dichlorophenoxyacetic acid (2,4-D) instead of CW. Rapidly growing cultures were established and were sub-cultured monthly. Somatic embryogenesis was induced following sub-culture from MS medium with 2,4-D to MS without growth regulators and with or without activated charcoal (0.5%). Germination of somatic embryos appeared to be enhanced by 1 mg l^?1 benzyladenine (BA); however, most of the germinating embryos became embryogenic.     

Adventitious shoot formation from sections of sweet potato grown in vitro

Sweet potato (Ipomoea batatas Lam.) root sections were obtained from the cultivars ‘Centennial’, ‘Redmar’ and ‘Jewel’ with a No. 6 cork borer. These sections were cut into 2–3-mm discs and explanted on to modified Murashige and Skoog (MS) medium consisting of MS high mineral salts, myo-inositol (100 mg l^?1), Staba vitamins, 6-benzyl-aminopurine (2.0 mg l^?1), naphthaleneacetic acid (0.1 mg l^?1), sucrose (30 g l^?1) and agar (10 g l^?1). Root discs from internal regions of the tuberous roots gave rise to calli and meristematic bud-like centers (MBLC's). A small percentage of ‘Centennial’ MBLC's burst open to reveal plantlets which grew and rooted well on the medium. Some of the ‘Jewel’ MBLC's contained only roots, while those of ‘Redmar’ did not differentiate. MBLC-formation occurred most often on discs taken from fresh (unstored) roots of ‘Centennial’. Petiole sections taken from in vitro-cultured plants of all 3 cultivars developed plants quite readily on the medium. Shoots of all 3 cultivars grew rapidly, to yield whole rooted plants which could easily be moved to soil and grown in the greenhouse and field.     

Effects of grafting height of MM106 rootstock on growth,lateral shoot formation and yield in apple trees

Summary

Between 2004 and 2008, the effects of different grafting heights on sylleptic shoots were tested in the apple (Malus domestica Borkh.) cultivars ‘Granny Smith’ and ‘Gloster’, and cumulative fruit yields were evaluated. MM106 apple rootstocks were grafted 10, 20, 40, or 60 cm above soil level in August 2004. The results showed that an increased grafting height significantly decreased tree height in both cultivars. The tallest and shortest trees were observed at grafting heights of 10 cm (153.0 and 170.0 cm) and 60 cm (141.3 and 143.5 cm) in ‘Granny Smith’ and ‘Gloster’, respectively.Among the various grafting heights tested, 60 cm in ‘Granny Smith’ and 20 cm in ‘Gloster’ gave the largest stem diameters (17.6 mm and 16.8 mm, respectively). The number of lateral shoots increased significantly with increased grafting height in both cultivars. The largest numbers of lateral shoots in ‘Granny Smith’ (10.75) and ‘Gloster’ (2.00) were obtained from a grafting height of 60 cm, while 2.55 and zero lateral shoots occurred at 10 cm grafting height in ‘Granny Smith’ and ‘Gloster’, respectively. Shoot lengths decreased significantly by increasing the grafting height. Grafting heights of 10 cm and 60 cm resulted in the tallest and shortest shoots in both cultivars. Cumulative fruit yields were significantly affected by grafting height in both cultivars. The highest yield was found for a 60 cm grafting height in both ‘Granny Smith’ (11.295 kg tree^–1) and ‘Gloster’ (4.818 kg tree^–1).The results of this study suggest that grafting heights of 40 cm and 60 cm have the potential to promote branching and early bearing for apple fruit production in sustainable and organic agricultural systems.     

Cyanogenic D-amygdalin contents of the kernels of cultivated almonds and wild Amygdalus webbii Spach.

SUMMARY

D-amygdalin is a toxic compound found in the kernels of some bitter almond cultivars.This compound is toxic because of its potential to release poisonous hydrogen cyanide. The D-amygdalin contents of the kernels of 18 commercial almond cultivars (Prunus dulcis Mill. = Amygdalus communis L.) and three wild genotypes (Amygdalus webbii Spach.) were determined by HPLC. In initial tests, two extraction procedures [100% (v/v) methanol or 4% (w/v) citric acid)], two different kernel cutting sizes (powdered or roughly-cut pieces), and two shaking techniques (mechanical shaking or sonication) were assessed. The results obtained showed that the method of extraction can have a strong effect on the extent of recovery of the potentially toxic compound, which varied by a factor of approx. 20-fold across the different extraction techniques.The greatest recovery of D-amygdalin from wild almond kernels was achieved with mechanical shaking of roughly-cut kernels in 100% (v/v) methanol, and this procedure was applied for all subsequent analyses of the D-amygdalin contents of all genotypes. The highest amounts of D-amygdalin were found in “bitter” cultivars and wild genotypes (716 – 23,025 mg kg^–1), with lower values in “sweet” cultivars (0 – 158 mg kg^–1). High levels of variability were observed both among the 18 almond cultivars and the A. webbii genotypes tested.     

Foliar application of calcium plus boron reduces the incidence of sunburn in ‘Golden Delicious’ apple

Summary

Losses of apple fruit due to sunburn damage under South African climatic conditions can reach up to 40% per annum for specific cultivars in certain years. Various approaches to reduce the incidence and severity of sunburn resulted in temporary effects but, at present, no single remedy is available to provide a significant and consistent reduction in sunburn damage on a commercial scale. ‘Golden Delicious’ apple trees that received both calcium (Ca) and boron (B) as foliar applications on a weekly basis, when applied from approx. 21 – 70 d after full bloom (DAFB), showed significantly less sunburn in two consecutive seasons (P = 0.0500 and P = 0.0247 respectively) than untreated control fruit, or treatments based on Ca alone. The minerals were applied as supplements of sugar-alcohol complexed with Ca and B, trading as Manni-Plex^® Ca [10% (w/w) Ca] and Manni-Plex^® B [3.3% (w/w) B], respectively. The mode of action by which the incidence of sunburn was reduced using combined sprays of Manni-Plex^® Ca plus Manni-Plex^® B remains to be elucidated.