Mature Apple Research Articles

Microarray analysis of apple gene expression engaged in early fruit development

To evaluate gene expressions mostly engaged in early development of apple fruit, we performed the identification of transcripts differentially expressed in young fruit by using microarrays spotted with 6,253 cDNAs collected from young and mature apple fruits of the cultivar Fuji (Malus domestica Borkh. cv. Fuji). A total of 3,484 cDNAs out of 6,253 were selected after quality control of microarray spots and analyzed for differential gene expression patterns between young fruit and other tissues (mature fruit, leaf and flower). Among them, 192 cDNAs displayed a signal value higher than twofold in young fruit compared with other tissues. Blast analysis of the 192 cDNA clones identified 88 non-redundant groups encoding proteins with known function and 50 non-redundant groups with unknown function. The putative protein products were classified into the following categories: photosynthesis (16.7%), protein synthesis (12.3%), cell proliferation and differentiation (10.9%), cell enlargement (5.8%), metabolism (8.0%), stress response (7.2%), others (2.9%), and unknown functions (32.2%). Furthermore, confirming the microarray data by reverse transcription-polymerase chain reaction revealed that the wide range of transcripts differentially expressed in young fruit was expressed in other organs but not in the mature fruit. The data presented suggested that apple fruit development depends on the tight regulation of the expression of a number of genes, which are also expressed in other organs.

Bruise susceptibilities of ‘Gala’ apples as affected by orchard management practices and harvest date

This study evaluated the influences of irrigation (frequent versus none), crop load (high versus low), and nitrogen (urea fertilizer versus none) on bruise sensitivity of mature apple fruit (cv. Gala) picked on three harvest dates. It includes a proposal for a new index of bruise sensitivity, called specific bruise susceptibility, as an additional tool for studying the effects of management practices on bruising of fresh produce. Results obtained showed that reducing irrigation frequency and practising selective and timely picking of mature fruit offer some potential to reduce fruit susceptibility to bruising. Analyses of the effects of orchard management practices based on specific bruise susceptibility of fruit (mm 3 J −1 g −1) suggested that other biophysical fruit properties such as curvature (shape) and maturity status (rather than size alone) may have greater influence on the way in which induced variations in fruit size (e.g. through crop loading and irrigation) respond to mechanical loads during impact bruising.

Effect of Drip Boron Fertigation on Yield and Fruit Quality in a High-Density Apple Orchard

ABSTRACT This study was carried out in 2001–2003 at the Experimental Orchard of the Research Institute of Pomology and Floriculture, Skierniewice, Poland, on mature ‘Jonagold’ apple (Malus domestica Borkh.) trees (M.26 EMLA) planted at 4 × 2.5 m spacing on a sandy loam soil with low boron (B) availability. The trees were drip fertigated with B at rates of 0.5, 1, or 1.5 g tree− 1 over 4 weeks at 3-d intervals beginning at the stage of bud break. Plants that did not receive B via drip irrigation system served as a control. Drip B fertigation effectively increased water-soluble B concentrations in the soil and the status of this microelement in leaves of current season shoots. However, the B fertigation had no effect on tree vigor. In 2 out of 3 years, the drip B fertigation improved flower B status, fruit set, and yield. The efficiency of the drip B fertigation was not influenced by B rate. In all growing seasons, the drip B fertigation increased B level and a soluble solids concentration in the fruit flesh, but had no effect on mean fruit weight, color, titratable acidity, and fruit firmness. It was concluded that on coarse-textured soils with low B availability, the drip B fertigation of mature apple trees in high-density orchards can be recommended from the stage of bud burst to petal fall at a rate of 0.5 g tree− 1.

Evaluation of plant-based water status indicators in mature apple trees under field conditions

The performance of different indicators of plant water status as a tool for irrigation management was evaluated in mature field grown ‘Golden Delicious’ apple trees during the late summer of 1998. Control (C) and stress (S) treatments were studied. In the C treatment trees were irrigated daily at 100% ETc whereas in the S treatment water was withheld during 31 days (DOY’s 236–266). Predawn water potential (Ψpd) and midday stem water potential (Ψstem) were measured several times a week during the experimental period. Three daily measurements of stomatal conductance (gs) and stem water potential were made during five consecutive days in mid-September. Trunk diameter changes (TDC) were recorded by LVDT sensors, and from these measurements, maximum daily shrinkage (MDS), daily growth (DG), and cumulative growth (CG) were calculated. Midday Ψstem showed the best ratio between the response to moderate water stress and tree variability (“signal/noise” ratio) among the indicators studied here, followed closely by Ψpd. On the other hand, the poorest water status indicator was gs. Due to the low trunk growth rate of the trees, and its high variability, DG and CG were not adequate indicators. MDS showed a lower sensitivity to water stress and a higher variability (CV = 0.19) than midday Ψstem (CV = 0.08) and Ψpd (CV = 0.10). However, MDS correlated well with ET0 and with midday Ψstem (R2 = 0.79) thus, making this parameter an interesting and promising tool for irrigation management in apple orchards. More research needs to be done in order to define reference values for MDS and plant water potential indicators, in relation to evaporative conditions and in different phenological periods, and to quantify the relationship between water status indicators values and apple tree yield and fruit quality.

First Report of Phomopsis Fruit Decay on Apple Caused by Phomopsis mali in Greece.

From 2002 to 2005, a previously unreported disease causing significant yield losses was observed on apple fruits (cv. Red Chief) in the region of Imathia in northern Greece. Almost all apple orchards in that area, cultivated with Red Chief, showed disease symptoms on 3 to 10% of the fruits. Diseased fruits showed irregularly shaped, water-soaked areas on the skin and extensive decay internally. In most of the fruits, decay appeared to initiate internally from the calyx tube. Infected fruits remained firm during the early stages of decay. Fungal isolates obtained from small pieces of decayed tissue on potato dextrose agar (PDA) medium were identified as Phomopsis mali Roberts on the basis of morphological characteristics (2). Cultures grew rapidly on PDA at 22°C in the dark. They were initially white, but approximately 30 days after inoculation they turned gray because of the formation of pycnidia that contained α- and β-spores. α -Spores were short and elliptical in shape (8 to 10 × 2 to 3 μm) while β-spores were long (22 to 25 × 1 to 2 μm). Pathogenicity of the isolated cultures was tested by wound inoculating five mature apple fruits (cv. Red Chief) after surface sterilization with 0.5% NaOCl. PDA plugs, 5 mm in diameter with actively growing mycelium, were transferred into the flesh of the fruits. Sterile PDA plugs were used to inoculate five control apple fruits. Inoculated fruits were kept at 23°C for 10 days in the growth chamber. Extensive decay, similar to that observed on diseased fruits in the field, was observed on the inoculated fruits, whereas control fruits showed no decay. P. mali was reisolated from the decayed tissues. Commercial losses due to fruit decay caused by the pathogen have previously been reported in the United States and Northern Ireland (1). To our knowledge, this is the first report of Phomopsis fruit decay on apples in Greece.

Influence of prohexadione calcium (Apogee®) on shoot growth of non-bearing mature apple trees in two different growing regions

Orchard experiments were conducted on mature non-bearing apple ( Malus × domesticaBorkh.) trees to determine the efficacy of prohexadione-calcium (PC), formulated as Apogee® [27.5% PC + 56.1% (NH4)2 SO4 +16.4% ot her proprietary additives] for shoot growth control on six cultivars grown in Ontario (ON) and one grown in New Brunswick (NB), Canada. Seasonal patterns of extension shoot growth among cultivars in both locations were also compared. Results indicate that PC applications are most effective at the beginning of the season, when relative growth rates were greatest in eastern Canada. Four applications of PC failed to significantly reduce shoot growth more than two applications in either location. However, the level of control might have been more effective in ON if treatment applications were initiated earlier in the season. Although tree vigor and shoot growth differed between cultivars and locations, PC significantly and consistently reduced shoot growth and relative shoot growth rates for all cultivars at both locations. Empire shoots treated with PC were approximately 33 and 37% shorter at the end of the season in NB and ON, respectively. Key words: Calcium 3-oxido-5-oxo-4-propionylcyclohex-3-enecarboxylate, anti-giberellin, plant growth regulator, relative growth rate, Malus

Root-zone temperatures affect phenology of bud break, flower cluster development, shoot extension growth and gas exchange of 'Braeburn' (Malus domestica) apple trees

We investigated the effects of root-zone temperature on bud break, flowering, shoot growth and gas exchange of potted mature apple (Malus domestica (Borkh.)) trees with undisturbed roots. Soil respiration was also determined. Potted 'Braeburn' apple trees on M.9 rootstock were grown for 70 days in a constant day/night temperature regime (25/18 degrees C) and one of three constant root-zone temperatures (7, 15 and 25 degrees C). Both the proportion and timing of bud break were significantly enhanced as root-zone temperature increased. Rate of floral cluster opening was also markedly increased with increasing root-zone temperature. Shoot length increased but shoot girth growth declined as root-zone temperatures increased. Soil respiration and leaf photosynthesis generally increased as root-zone temperatures increased. Results indicate that apple trees growing in regions where root zone temperatures are < or = 15 degrees C have delayed bud break and up to 20% fewer clusters than apple trees exposed to root zone temperatures of > or = 15 degrees C. The effect of root-zone temperature on shoot performance may be mediated through the mobilization of root reserves, although the role of phytohormones cannot be discounted. Variation in leaf photosynthesis across the temperature treatments was inadequately explained by stomatal conductance. Given that root growth increases with increasing temperature, changes in sink activity induced by the root-zone temperature treatments provide a possible explanation for the non-stomatal effect on photosynthesis. Irrespective of underlying mechanisms, root-zone temperatures influence bud break and flowering in apple trees.

Infection frequency of mature apple fruit with Erwinia amylovora deposited on pedicels and its survival in the fruit stored at low temperature

The infection frequency of mature apple fruit by Erwinia amylovora and the survival of E. amylovora in the fruit stored at low temperature were investigated. The fruit stems (pedicels) of 460 mature apple fruit were inoculated with 105 or 104 cfu of bioluminescent E. amylovora, tagged with lux genes. Nine days after inoculation, 43% and 27% of the fruit inoculated with 105 and 104 cfu, respectively, were infected. All infected fruit looked healthy. After 6 months of storage at 5°C, almost all of the 142 infected fruit had viable E. amylovora. Of the fruit containing E. amylovora internally, 19.5% had latent infections and the rest had blight symptoms. E. amylovora was not uniformly distributed in the fruit flesh, and internal brown lesions were observed where E. amylovora was densely distributed. These findings showed that mature apple fruit may be infected with E. amylovora, especially as latent infections, and act as a source for long-range dissemination.

Erratum to: Invasion and colonization of mature apple fruit by Erwinia amylovora tagged with bioluminescence genes

Invasion and colonization of mature apple fruit by a transformant of Erwinia amylovora tagged with bioluminescence genes from Vibrio fischeri was examined. The transformant was deposited on cut surfaces of fruit stems, wounds on the shoulders and calyces, injured fruit-bearing twigs of harvested apple fruit, and cut fruit flesh. After incubation in closed stainless steel or plastic boxes at 25°C, fruit were periodically observed with a two-dimensional luminometer. The presence of the transformant in luminous areas was confirmed by isolating it on selective media. E. amylovora, when deposited in fruit stems: (1) can invade mature as well as immature apple fruit; (2) vertically and horizontally spreads and colonizes along vascular bundles, increasing its population; (3) reaches the calyx end and the flesh just under the exocarp within 3–4 days after inoculation; (4) when deposited on cut fruit flesh, irrespective of its maturity, can easily increase its population and survive 2–4 weeks or more at 25°C; and (5) even at the time of fruit maturation, can migrate within twigs rapidly and reaches the abscission layers between fruit-bearing twigs and fruit stems.

Invasion and colonization of mature apple fruit by Erwinia amylovora tagged with bioluminescence genes

Invasion and colonization of mature apple fruit by Erwinia amylovora tagged with bioluminescence genes

Apple and peach fruit volatiles and the apple constituent butyl hexanoate attract female oriental fruit moth, Cydia molesta, in the laboratory

Abstract:Volatiles emitted from immature and mature peach and apple fruits were all attractive to mated female oriental fruit moth, Cydia molesta (Busck), in a dual choice arena. Females did not discriminate between odours emitted by these two major host plants. The same natural blends were behaviourally ineffective for virgin females. A major component of apple fruit volatiles, butyl hexanoate, also attracted female C. molesta. Mated females were attracted to two medium dosages, while virgin females responded positively to the lowest of the five dosages tested. The time course of the captures of the moths shows a diurnal activity cycle known from the field. The possible implications of a semiochemical which attracts females are discussed in the context of previous findings that gravid females may immigrate from peaches into apple orchards particularly in the later phase of the season.

Response of several apple tree cultivars to chemical thinner sprays

Introduction. The chemical fruit thinning of apple trees carried out after flowering is a current practice used to improve fruit size and quality, to ensure the return of flowering and to reduce the biennial bearing. Our work studied the effectiveness of two particular chemical thinners (Accel and carbaryl) applied to three apple tree cultivars, and their effects on the fruit yield and quality. Materials and methods. Two identical experiments were undertaken on mature apple trees in 1995 and 1996. They made it possible to test spraying after flowering of Accel and carbaryl at three different concentrations and applied to the three `Empire', `Jan-A-Red' and `Braeburn' apple tree cultivars. The effect of the chemical substances was evaluated with parameters of fruit set, fruit quality and yield. Results and discussion. For the three apple tree cultivars studied, the spraying of Accel and carbaryl made it possible to reduce the fruit set and to improve the apple yield, pH and soluble solids concentrations. However, the treatments did not affect the fruit seed number, the fruit length and diameter, or the [fruit length / fruit diameter] ratio. Conclusion. With the concentrations used, Accel and carbaryl were effective for thinning the three apple tree cultivars tested. These chemical thinners increased yield and improved certain parameters of the apple quality.

Comparison of microcapsule density with various apple tissues and formulations of oriental fruit moth (Lepidoptera: Tortricidae) sprayable pheromone.

The density of microcapsules was compared on 'Golden Delicious' mature and immature foliage, fruit, and 1-yr-old limbs after dip treatments with Phase III oriental fruit moth, Grapholita molesta (Busck), microencapsulated pheromone. Microcapsules were counted with a dissecting microscope at 50x magnification after apple tissues were treated with a two-step dye staining process to increase the visibility of the microcapsules. The number of Phase III microcapsules on 1-yr limbs treated with a field concentration was two- to threefold greater than the number of microcapsules on similarly treated fruit or foliage. Phase I, III, and V OFM MEC and Checkmate OFM-F formulations of microencapsulated pheromone also were compared to determine their abundance on mature apple foliage. The Phase V OFM MEC formulation had the highest density of microcapsules when mature foliage was treated at the field rate. The Phase I treatment had the greatest difference between upper and lower leaf surfaces with 18-fold greater microcapsule density on the upper surface. On mature apple leaves treated with Phase III MEC, the number of microcapsules/cm2 was two- to threefold greater on fields of view without the mid-vein than those that included the mid-vein. The cuticle structure and abundance of trichomes are two factors that may have contributed to differences in microcapsule density among plant tissue types, top and bottom leaf surfaces, and fields of view with and without the mid-vein.

Changes in Photosynthesis and Carbohydrate Metabolism in Mature Apple Leaves in Response to Whole Plant Source-Sink Manipulation

Photosynthesis and carbohydrate metabolism in apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] source leaves were monitored during a 7-day period after source-sink manipulations by girdling or partial defoliation treatments. In the girdling treatment, sorbitol, sucrose, glucose, and starch accumulated in leaves, and net photosynthetic rates (Pn) at 350 μL·L-1 CO2 decreased during a 7-day period. Pn measured at 1000 μL·L-1 [CO2] was also decreased but the changes were less. Stomatal conductance and intracellular CO2 concentration decreased markedly in leaves of girdled shoots. When shoots were partially defoliated, starch and glucose concentrations in remaining source leaves declined steadily during the 7-day study period. Sorbitol and sucrose concentrations decreased during the first 2 days after defoliation, then increased the following 5 days. Pn of the remaining leaves measured at ambient and elevated CO2 levels were enhanced markedly. Aldose-6-phosphate reductase activity in source leaves increased markedly from 27.5 to 39.2 μmol·h-1·g-1 fresh weight (FW) after partial defoliation but remained unchanged in leaves after girdling. Selective and maximum sucrose phosphate synthase (SPS) activities increased following partial defoliation and decreased following girdling. ADP-glucose pyrophosphorylase activity remained relatively unchanged in the partial defoliation treatments but increased markedly in the girdled-shoot leaves. These results suggested that girdling-induced photosynthetic inhibition is mainly due to stomatal limitation, however, the photosynthesis enhancement by partial defoliation may be due primarily to acceleration of photosynthetic capacity per se. These studies showed that the metabolism of sorbitol, sucrose and starch, three photosynthetic end products in mature apple leaves, was coordinately regulated in source leaves in response to source-sink manipulations.

Modelling water uptake by a mature apple tree

We report the results from a field experiment in which we examined the spatial and temporal patterns of water uptake by a mature apple tree (Malus domestica Borkh., 'Splendour') in an orchard. Time domain reflectometry was used to measure changes in the soil's volumetric water content, and heat-pulse was used to monitor locally the rates of sap flow in the trunk and roots of the tree. The tree's distribution of root-length density and supporting data to characterise the soil's hydraulic properties were determined for the purpose of modelling soil water movement in the root-zone under an apple tree. Experimental data are compared against the output from a numerical model of the soil water balance that uses Richards' equation for water flow, and uses a distributed macroscopic sink term for root uptake. In general, there was a very good agreement between the measured and modelled results. The apple trees consumed some 70 L of water per day during the middle of summer. The daily water use declined to about 20 L per day with the onset of autumn, coinciding with a reduced evaporative demand and an increasing number of rain days. Water movement in the root-zone soil was dominated by the water uptake via surface roots. Large changes in soil water content were also associated with each irrigation event. Our experimental data support the contention that more frequent irrigation in smaller doses will result in less water percolating through the root-zone. Such an irrigation strategy should make more efficient use of water by minimising the leaching losses. It will also be helpful for environmental protection by reducing the percolation losses of water and solute beyond the grasp of the roots.

EVALUATION OF BUFFER ZONE SIZE AND INSPECTION NUMBER REDUCTION ON PHYTOSANITARY RISK ASSOCIATED WITH FIRE BLIGHT AND EXPORT OF MATURE APPLE FRUIT

EVALUATION OF BUFFER ZONE SIZE AND INSPECTION NUMBER REDUCTION ON PHYTOSANITARY RISK ASSOCIATED WITH FIRE BLIGHT AND EXPORT OF MATURE APPLE FRUIT

Apple leaf sucrose-phosphate synthase is inhibited by sorbitol-6-phosphate.

Sucrose-phosphate synthase (SPS) from mature apple (Malus domestica Borhk. cv. Gala) leaves was purified 34-fold to a final specific activity of 15.3 μmol mg-1 protein h-1. The enzyme showed hyperbolic saturation kinetics for both fructose-6-phosphate (F6P) (Km= 0.36 mM) and uridine-5'-diphosphoglucose (UDPG) (Km = 6.49 mM). Glucose-6-phosphate (G6P) was found to be an activator of apple SPS, and the activation was dependent upon the F6P concentration. At a concentration of 2 mM, G6P significantly decreased the Km for F6P and increased SPS activity. However, higher concentrations of G6P did not further stimulate SPS activity. In contrast to SPS from other plant species, inorganic phosphate (Pi) had little or no inhibitory effect on apple SPS. The apple leaf enzyme was inhibited 7-10% by 10 mM Pi when F6P concentrations were in the range of 2-10 mM. We observed that sorbitol-6-phosphate, an intermediate metabolite in sorbitol biosynthesis, was a competitive inhibitor of SPS with a Ki of 1.83 mM. Sorbitol-6-phosphate also inhibited G6P activation of SPS. Our results suggest that sucrose biosynthesis may be altered by the products of sorbitol biosynthesis in apple leaves.

Annual dry-matter production by three apple cultivars at four within-row spacings in New Zealand

SummaryAnnual dry-matter production was estimated from eight year old apple trees of ‘Fuji’, ‘Braeburn’ and ‘Royal Gala’ on rootstock M.9, trained as slender spindles, in a spacing trial with trees spaced at 1.3, 1.5, 1.9 and 2.4 m within the row with tree rows 3.5 m apart. Light interception was recorded at intervals during the season. Both fresh weight yield and total dry-matter production were linear functions of light interception, with a higher slope recorded for the two late season cultivars compared with the early maturing ‘Royal Gala’. Comparison of the relationship between mid-season light interception and apple yields with published values from elsewhere, reveals that the slope of the relationship is enhanced under New Zealand conditions. The relationship suggests an upper limit of yield of 169 t ha–1 at 90% light interception, slightly higher than the maximum yield recorded of 163 t ha–1. Energy conversion of intercepted light over the growing season into dry-matter production was similar to that observed in the United Kingdom, suggesting that the major climatic advantage in New Zealand over the United Kingdom is the higher growing season radiation integral. Dry matter was allocated in the order fruit>woody tissue>leaves, with partitioning to the fruit of 74, 72 and 63% for ‘Braeburn’, ‘Fuji’ and ‘Royal Gala’, respectively. Under New Zealand conditions, sustainable 70% harvest index values may be achievable for mature apple trees on dwarfing rootstock with late maturing cultivars.

Effect of foliar- and soil-applied boron in deciduous fruit orchards 1: apple and pear

Between autumn 1996 and May 1998 a variety of boron (B) treatments were applied to mature apple and pear trees on soils containing 0.3 to 0.5 mg B kg−1. Average mid-season apple leaf B levels in the B treatments were higher than in the controls, by 5.0% in 1997 and 7.9% in 1998. Corresponding increases in pear leaf B levels were 1.5% and 3.9%. Increases in fruit B contents were comparatively large: 31% and 33% in apple, 77% and 46% in pear. Increased leaf and fruit B levels were most consistently promoted by four early-season sprays, each containing about 20 g B 100 I−1 followed by one 41.6 g B 100 I−1 spray in autumn. Apple and pear leaf and fruit B levels were not affected by treatments in which one B spray was applied in spring. Treatments in which a single spring B spray was followed by one B spray in autumn increased pear leaf and fruit B in 1997 but had no effect on apple. Apple and pear leaf and fruit B levels did not increase in response to increases in the B content of the autumn spray. Applications of B to the soil had no effect on leaf and fruit B levels unless they were accompanied by four early season sprays, each containing about 20 g B 100 I−1. In both apple and pear, the 0.02 M CaCI2 extractable soil B levels correlated better with the levels of B in the fruit, than in the leaves. Leaf and fruit B levels correlated in pear, but not apple. Boron sprays, and soil B applications, had no effect on the number of seeds in apple and pear fruit.

Plant and host effects on the leafroller parasitoid Dolichogenidia tasmanica

AbstractParasitism by the braconid wasp Dolichogenidia tasmanica of first instar larvae of the lightbrown apple moth Epiphyas postvittana, established on four different species of potted host plants, was assessed after 2 weeks of field exposure in an apple orchard. Parasitism varied significantly between larval host plants (apple 58%, broom 59%, clover 30%, poplar 19% ). Parasitism on potted apple seedlings of the co‐evolutionary host, E. postvittana, was compared in a field trial with that of two native New Zealand leafroller species (to which D. tasmanica has had exposure for 5 decades only). Parasitism varied significantly with larval host (E. postvittana, 83%; Ctenopseustis herana, 58%;Planotortrix octo, 26% ). Larval collections were made from mature apple trees and identification of larvae was achieved by DNA analysis for the leafroller species using PCR‐RFLP of ITS1 + ITS2, and for the parasitoid by specific PCR of partial 18S. Parasitism under natural field conditions on mature apple trees was not different between larval hosts (mean 32.5% ). In laboratory studies, more P. octo larvae departed in response to parasitoid probing behaviour than E. postvittana, which is likely to contribute to the difference in parasitism rates. This study conclusively shows that D. tasmanica parasitises native New Zealand leafrollers, despite their different evolutionary origins.