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At least 19 recordsLinked to original sources

PubMed2005

13C-photosynthate accumulation in Japanese pear fruit during the period of rapid fruit growth is limited by the sink strength of fruit rather than by the transport capacity of the pedicel.

In Japanese pear, the application of GA3+4 during the period of rapid fruit growth resulted in a marked increase in pedicel diameter and bigger fruit at harvest. To elucidate the relationship between pedicel capacity and fruit growth and to determine the main factor responsible for larger fruit size at harvest, fruit growth and pedicel vascularization after GA application were examined and the carbohydrate fluxes were monitored in a spur unit by non-invasive techniques using 13C tracer. Histological studies of fruit revealed that GA increased the cell size of the mesocarp but not the cell number and core size. The investigation of carbon partitioning showed that an increase in the specific rate of carbohydrate accumulation in fruit or the strength of fruit should be responsible for an increase of fruit weight in GA-treated trees. Observation of pedicel vascularization showed that an increase in pedicel cross-sectional area (CSA) by GA application mainly resulted from phloem and xylem CSA, but it is unlikely that an increase in the transport system is the direct factor for larger fruit size. Therefore, it can be concluded that larger fruit size resulting from GA application during the period of rapid fruit growth caused an increase in the cell size of the mesocarp and increased carbon partitioning to the fruit. Although GA is closely involved with pedicel vascularization, it seems that photosynthate accumulation in fruit is limited by the sink strength of fruit rather than by the transport capacity of the pedicel.

Biological Transport, Active↗

PubMed2005

A virtual peach fruit model simulating changes in fruit quality during the final stage of fruit growth.

A virtual fruit model simulating seasonal changes in several peach (Prunus persica (L.) Batsch) fruit quality traits during the final growth stage is presented. The quality traits considered are fruit size, the proportion of total fruit mass consisting of fruit flesh, dry matter content of the flesh and the concentrations of sucrose, glucose, fructose and sorbitol in the flesh, which are used to calculate a sweetness index. The virtual peach fruit model was developed by adapting and integrating three existing process-based models describing fruit dry mass growth, fruit fresh mass growth and sugar accumulation in the flesh into one complex system. Data sets of peach fruit growth and quality obtained from one field site over several years were used to estimate parameters and evaluate the virtual peach fruit model. Output from the model showed good agreement with the field data. Insight into the complex nature of the virtual peach fruit model, i.e., its ability to show emergent properties, was accomplished by conducting a series of theoretical experiments. The virtual peach fruit model was shown to be sensitive to management and environmental factors (leaf:fruit ratio, stem water potential and, to a lesser extent, weather). Its ability to generate simple laws relating to physiological variables and quality parameters was also demonstrated. Finally, the virtual peach fruit model was able to reveal complex behaviors resulting from changes in water potentials or leaf:fruit ratios over time.

Fruit↗

PubMed2004

Revised irradiation doses to control melon fly, Mediterranean fruit fly, and oriental fruit fly (Diptera: Tephritidae) and a generic dose for tephritid fruit flies.

Currently approved irradiation quarantine treatment doses for Bactrocera cucurbitae (Coquillet), melon fly; Ceratitis capitata (Wiedemann), Mediterranean fruit fly; and Bactrocera dorsalis (Hendel), oriental fruit fly, infesting fruits and vegetables for export from Hawaii to the continental United States are 210, 225, and 250 Gy, respectively. Irradiation studies were initiated to determine whether these doses could be reduced to lower treatment costs, minimize any adverse effects on quality, and support a proposed generic irradiation dose of 150 Gy for fruit flies. Dose-response tests were conducted with late third instars of wild and laboratory strains of the three fruit fly species, both in diet and in fruit. After x-ray irradiation treatment, data were taken on adult emergence, and adult female fecundity and fertility. Melon fly was the most tolerant of the three species to irradiation, and oriental fruit fly was more tolerant than Mediterranean fruit fly. Laboratory and wild strains of each species were equally tolerant of irradiation, and larvae were more tolerant when irradiated in fruit compared with artificial diet. An irradiation dose of 150 Gy applied to 93,666 melon fly late third instars in papayas resulted in no survival to the adult stage, indicating that this dose is sufficient to provide quarantine security. Irradiation doses of 100 and 125 Gy applied to 31,920 Mediterranean fruit fly and 55,743 oriental fruit fly late third instars, respectively, also resulted in no survival to the adult stage. Results support a proposed generic irradiation quarantine treatment dose of 150 Gy for all tephritid fruit flies.

Animals↗

PubMed2003

Mycotoxins in fruits, fruit juices, and dried fruits.

This review gives an overview of the presence of mycotoxins in fruits. Although several mycotoxins occur in nature, very few (aflatoxins, ochratoxin A, patulin, Alternaria toxins) are regularly found in fruits. It has been shown that the presence of fungi on fruits is not necessarily associated with mycotoxin contamination. The formation of mycotoxins depends more on endogenous and environmental factors than fungal growth does. Mycotoxins may remain in fruits even when the fungal mycelium has been removed. Depending on the fruit and the mycotoxin, the diffusion of mycotoxins into the sound tissues of fruits may occur. The influence of the selection and storage of fruits and the influence of different processing steps involved in the production of fruit juices and dried fruits on possible mycotoxin contamination is described. It is shown that the careful selection, washing, and sorting of fruits is the most important factor in the reduction of mycotoxin contamination during the production of fruit juices. The processing of fruits does not result in the complete removal of mycotoxins.

Aflatoxins↗

PubMed1999

Antisense inhibition of tomato fruit sucrose synthase decreases fruit setting and the sucrose unloading capacity of young fruit.

The role of sucrose synthase (SuSy) in tomato fruit was studied in transgenic tomato (Lycopersicon esculentum) plants expressing an antisense fragment of fruit-specific SuSy RNA (TOMSSF) under the control of the cauliflower mosaic virus 35S promoter. Constitutive expression of the antisense RNA markedly inhibited SuSy activity in flowers and fruit pericarp tissues. However, inhibition was only slight in the endosperm and was undetectable in the embryo, shoot, petiole, and leaf tissues. The activity of sucrose phosphate synthase decreased in parallel with that of SuSy, but acid invertase activity did not increase in response to the reduced SuSy activity. The only effect on the carbohydrate content of young fruit was a slight reduction in starch accumulation. The in vitro sucrose import capacity of fruits was not reduced by SuSy inhibition at 23 days after anthesis, and the rate of starch synthesized from the imported sucrose was not lessened even when SuSy activity was decreased by 98%. However, the sucrose unloading capacity of 7-day-old fruit was substantially decreased in lines with low SuSy activity. In addition, the SuSy antisense fruit from the first week of flowering had a slower growth rate. A reduced fruit set, leading to markedly less fruit per plant at maturity, was observed for the plants with the least SuSy activity. These results suggest that SuSy participates in the control of sucrose import capacity of young tomato fruit, which is a determinant for fruit set and development.

Caulimovirus↗

PubMed1986

Radiation preservation of foods of plant origin. Part V. Temperate fruits: pome fruits, stone fruits, and berries.

The current status of research on the application of ionizing radiation for improving the storage of temperate fruits, i.e., apple, pear, peach, nectarine, apricot, cherry, plum, strawberry, bilberry, cranberry, raspberry, and black currant, is reviewed. Changes in fruit metabolism, chemical composition, texture, and organoleptic quality attributes are discussed with reference to the irradiation dose. The feasibility of using radiation either alone or in conjunction with heat treatment, refrigeration, and controlled atmospheres (CA) for the control of storage decay caused by fungal pathogens is considered. Areas of further research are suggested before irradiation could be considered for practical application in some of these temperate fruits. The recent trends in the possible use of irradiation for disinfestation of certain pome and stone fruits and the prospects for the commercial utilization of irradiation for improving the market life of strawberries are discussed.

Carbohydrate Metabolism↗

PubMed1989

[Occurrence of nitrates and nitrites in certain frozen fruits, jams, stewed fruit and fruit-vegetable juices for children and in certain types of bee honey].

Nitrates and nitrites were evaluated spectrophotometrically by the method of Griess reaction, with previous reduction of nitrates to nitrites in a column filled with cadmium dust. The content of nitrates in frozen fruit (strawberries, black and red currant and plums) ranged from 2.50 to 57.38 mg KNO3/kg, with the highest content in garden strawberries. In cherry, strawberry, black and red currant jams the concentrations were from 6.30 to 97.38 mg KNO3/kg, the highest content was in cherry jam. In plum jam nitrates were found in low amounts from 11.65 to 12.09 mg/kg. In "Bobofrut" juices the nitrate content was higher than in the above products, ranging from 26.37 to 182.75 mg KNO3/kg. Nitrite content in all these groups of products was low, not exceeding 1 mg NaNO2/kg, with the exception of plum jam where the maximal value was found 1.65 mg NaNO2/kg. In stewed fruit and herb syrups and in honey nitrates ranged from 1.0 to 94.5 mg KNO3/kg. Nitrite content ranged from 0.17 to 1.92 mg/kg in herb syrups, from 0.0 to 1.20 mg/kg in stewed fruit, and from 0.0 to 0.40 mg NaNO2/kg in honey. The study showed that higher levels of nitrates were present as a rule in vegetable juices. However, the found concentrations were not harmful to the health of children, although this is possible in the case of carrot juice, especially when kept at room temperature for 24 hours.

Child↗

PubMed2003

Influence of branch autonomy on fruit, scaffold, trunk and root growth during stage III of peach fruit development.

We studied the influence of branch autonomy on the growth of reproductive and vegetative organs by establishing different patterns of fruit distribution within and between large branch units (scaffolds) in mature peach trees (Prunus persica (L.) Batsch cv. 'Elegant Lady'). Different patterns of fruit distribution were established by defruiting either whole scaffolds (uneven fruit distribution between scaffolds; US) or several selected hangers (small fruiting branches) per tree (uneven fruit distribution between hangers; UH). The effects of these patterns were compared with the effects of an even fruit distribution treatment (EVEN) in which fruits were thinned to achieve maximum uniformity of fruit distribution within the canopy. The desired fruit loads were obtained by differentially thinning the remaining bearing parts. On a tree basis, the response of mean fruit mass to fruit load was strongly affected by fruit distribution. The steepest mean fruit mass to fruit load relationship was found in US trees, whereas the relationship in UH trees was intermediate between the US and EVEN trees. On a scaffold basis, differences in fruit size between EVEN and US trees with similar fruit loads, though statistically significant, were relatively small, indicating that scaffolds were almost totally autonomous with respect to dry matter partitioning to fruit during the final stage of peach fruit growth. Hangers also appeared to exhibit significant autonomy with respect to the distribution of dry matter during the final phase of fruit growth. Branch autonomy was evident in scaffold growth: defruited scaffolds in the US treatment grew more than fruited scaffolds, and fruit distribution treatments had little impact on scaffold cross-sectional area on a tree basis. On the other hand, as observed for fruit growth, branch autonomy did not appear to be complete because the fruited scaffolds grew more in US trees than in EVEN trees under heavy cropping conditions. However, the effect of fruit distribution occurred only over short distances, and was negligible on organs located farther away from the source of heterogeneity (fruits), such as the trunk and roots.

Fruit↗

PubMed2003

The making of a bell pepper-shaped tomato fruit: identification of loci controlling fruit morphology in Yellow Stuffer tomato.

The heirloom tomato cultivar Yellow Stuffer produces fruit that are similar in shape and structure to fruit produced by the bell pepper varieties of garden pepper. To determine the genetic basis of this extreme fruit type in tomato, quantitative trait loci (QTL) analysis was performed on an F(2) population derived from a cross between Yellow Stuffer and the related species, Lycopersicon pimpinellifolium, which produces a small, round fruit typical of most wild species. F(2) plants were analyzed for both fruit size and the degree to which their fruit resembled the bell pepper. Three QTL were determined to influence bell pepper shape and seven QTL influenced fruit mass. The map positions of all three bell shape and six out of seven fruit size QTL appear to be allelic to components of fruit morphology analyzed in this population and to major fruit morphology QTL reported previously, adding support to the hypothesis that the majority of fruit size and shape variation in cultivated tomato is attributable to allelic variation at a limited number of loci. However, novel loci controlling components of fruit morphology, such as elongated fruit shape, bumpiness, number of seed per fruit and flowers per inflorescence were identified in this study as well. The three bell shape loci involved are: bell2.1, bell2.2 and bell8.1, and appear to correspond to locule number2.1 ( lcn2.1) and fruit weight 2.2 ( fw2.2) and fruit shape 8.1 ( fs8.1), respectively. The Yellow Stuffer alleles at lcn2.1 and fw2.2 increase locule number and fruit size, respectively, hence contributing to the overall bell pepper shape. The Yellow Stuffer allele at fs8.1 causes convex locule walls, giving the extended, bumpy shape characteristic of bell peppers. In addition, most fruit size QTL correspond to loci controlling number of flowers per inflorescence and/or stem-end blockiness. Comparisons among previously identified fruit morphology loci in tomato, eggplant and pepper suggest that loci affecting several aspects of fruit morphology may be due to pleiotrophic effects of the same, orthologous loci in these species. Moreover, it appears that the evolution of bell pepper-shaped tomato fruit may have proceeded through mutations of some of the same genes that led to bell pepper-type fruit in garden pepper.

Capsicum↗

PubMed1982

Fruit age and changes in abscisic Acid content, ethylene production, and abscission rate of cotton fruits.

The relationships of fruit age, abscisic acid (ABA) concentration, ethylene evolution, and abscission rates were studied in an effort to determine why cotton (Gossypium hirsutum L., cv. Deltapine 16) fruits rarely abscise more than 15 days after anthesis. Because abscission of cotton fruits is increased by conditions that limit photosynthesis, greenhouse-grown plants with fruits of various ages were placed in dim light for 3 days to induce high rates of fruit abscission. Abscission rates, ABA concentrations, and ethylene evolution rates were determined for fruits of various ages. Almost all of the young fruits abscised, but abscission rate declined with age until almost no abscission was observed in fruits that were 15 or more days past anthesis.Dim light increased the ABA concentrations of fruits that were 6 to 11 days old but did not increase ABA concentrations in fruits that were younger or older. The concentration of ABA declined with fruit age from peak values at 4 and 6 days after anthesis. Dim light also increased ethylene evolution from fruits up to 10 days old but had little effect on ethylene production or abscission of fruits more than 11 days old. Ethylene evolution declined with fruit age from peak values at 4 and 6 days after anthesis. Fruits of various ages (from plants not exposed to dim light) were sliced to induce high rates of wound ethylene production. The results indicated that the capacity for ethylene production declined with fruit age, parallel with a decline in abscission rate. Decreases in ABA concentration and ethylene evolution with fruit age indicate that change in the capacity to synthesize these hormones, especially in response to stress, is one cause of the decline in abscission rates as cotton fruits become older.

Journal Article↗

PubMed2002

Comparison of the nutrient content of fresh fruit juices vs commercial fruit juices.

OBJECTIVE: To compare the types and quantities of carbohydrate, electrolytes, pH and osmolarity of fresh fruit juices and commercial fruit juices. MATERIAL AND METHOD: Forty kinds of fresh fruits available in Thai markets were analyzed for types and quantities of carbohydrate, electrolyte, pH and osmolarity and compared with previously obtained data for commercial fruit juices. RESULTS: Most fresh fruit juices did not contain sucrose, whereas, commercial fruit juices mostly have sucrose in the range of 3-112 g/L. Although both fruit juices were acidic (pH varied from 3.6-6.7 and 3.2-5.8 of fresh juice and commercial juice), fresh fruit juices had a more neutral pH than commercial fruit juices. Apple, guava, orange, pear, and pineapple juices from commercial fruit juices had a high osmolarity compared with fresh fruit juices. All types of fresh fruit juices contained less sodium than commercial ones, whereas, most fresh fruit juices contained more potassium, phosphorus, and magnesium than commercial fluids. CONCLUSION: The nutrient content of fresh fruit juices and commercial fruit juices from the same kinds of fruits are not the same, possibly due to the manufacturing process. Therefore, physicians should know the composition of fruit juices in order to advise patients properly.

Beverages↗

PubMed1999

Early Application of Ethrel Extends Tomato Fruit Cell Division and Increases Fruit Size and Yield with Ripening Delay.

Flowers of tomato (Lycopersicon esculentum Mill.) plants cv. Castle Rock were sprayed with 100 ppm of ethrel, 0.5 mm aminooxyacetic acid (AOA), or water (control) 2 days after anthesis. The fruit period of cell division was extended up to 16-18 days after anthesis with the application of ethrel but reduced from 10-12 days (control) down to only 6-8 days with the application of AOA. In a trend opposite to AOA application, fruits that received ethrel treatment were of higher ethylene and 1-aminocyclopropane-1-carboxylic acid (ACC) levels than control. This was noticed not only during the first 2 weeks after anthesis but also during the fruit climacteric phase. Mesocarp cells of ethrel-treated fruits were greater in number/mm(2) but smaller in size than control; an opposite trend was obtained with the application of AOA. This was observed for a period of 18 days after anthesis, but by that time or at earlier ages, fruits of AOA treatment were larger in size and heavier in weight than control, and both were larger and heavier than ethrel-treated ones. At 5 weeks after anthesis and thereafter, the fruit response to all treatments was totally reversed because early ethrel-treated fruits became significantly larger in size and heavier in weight with a ripening delay of about 10 and 15 days compared with those of control and AOA-treated ones, respectively. When the same treatments were applied to the whole plant, similar results were obtained because the early application of ethrel increased the fruit yield by about 15% over control with a pronounced ripening delay; an opposite trend was obtained with the application of AOA. No significant differences were found among all treatments in terms of flower or fruit abscission or fruit number/plant. The data suggest that ethylene regulates tomato fruit transmission from cell division to cell enlargement. In addition, fruit cell division is terminated only when endogenous ethylene decreases to its basal level, allowing cell enlargement to dominate and proceed as in the case of the early application of AOA. The ripening delay of ethrel-treated fruits may be caused by the longer time required for the increased cell number to reach maturation. A low level of ethrel application at the tomato early fruiting stage may be used for increasing fruit yield by increasing fruit size and consequently its quality.Key Words. Tomato-Ethrel-AOA-Cell division-Cell enlargement-Ethylene-ACC-Ripeninghttp://link.springer-ny.com/link/service/journals/00344/bibs/18n1p15.html

Journal Article↗

PubMed2001

Relationship between tomato fruit growth and fruit osmotic potential under salinity.

To investigate the relationship between fruit growth and fruit osmotic potential (Psi(s)) in salty conditions, a sensitive tomato cultivar (Lycopersicon esculentum Mill.) and a tolerant accession of the wild species Lycopersicon pimpinellifolium Mill. were grown in a greenhouse with 0 and 70 mM NaCl, and the growth of the fruit studied from 15 to 70 days after anthesis (DAA). L. pimpinellifolium did not reduce significantly fruit weight in salty conditions throughout the growth period, whereas L. esculentum fruit weights decreased significantly with salinity from 45 DAA. L. esculentum fruit fresh weight reductions resulted from both less dry matter and water accumulation, although the fruit water content was affected by salinity before the fruit weight. In both species, fruit osmotic potential (Psi(s)) decreased significantly with salinity during the rapid fruit growth phase, although the changes were different. Thus, fruits from L. pimpinellifolium salt treated plants showed a Psi(s) reduction at the beginning (15 DAA) twice as high as that found in L. esculentum. As the advanced growth stage (from 15 to 55 DAA), the Psi(s) reduction percentages induced by salinity were quite similar in L. pimpinellifolium fruits, while increased in L. esculentum. Under saline conditions, the solutes contributing to reduce the fruit Psi(s) during the first 55 DAA were the inorganic solutes in both species, while in the ripe fruits they were hexoses. L. esculentum fruits accumulated K(+) as the main osmoticum in salty conditions, while L. pimpinellifolium fruits were able to use not only K(+) but also the Na(+) provided by the salt.

Journal Article↗

PubMed2006

Effects of fruit pre-harvest bagging on fruit quality of peach (Prunus persica Batsch cv. Hujingmilu).

Experiments were conducted to test the effects of pre-harvest bagging on fruit ripening and quality of peach (Prunus persica Batsch cv. Hujingmilu). Young fruits, at 50 days after full bloom (DAFB), were covered with bags made of single-, double-, and triple-layers of orange paper bag with 27.0%, 13.9% and 8.2% sunlight transmission, respectively. Ethylene production and respiration rate were measured, and fruit quality was analyzed at 111, 114, 117, 120 (firm-ripe stage) and 124 DAFB (full-ripe stage). Single- and triple-layer bagged fruits had higher ethylene production rates than double-layer bagged and un-bagged fruits. The skin of un-bagged fruit had higher brightness (L-value) but smaller hue angle (h degrees) at the full-ripe stage compared with that of bagged fruit. Flesh firmness of un-bagged fruit was higher than that of bagged fruit until the firm-ripe stage, although triple-layer bagged fruit had higher firmness than un-bagged fruit at the full-ripe stage. Total soluble solids in juice of single-layer bagged fruit were a little higher than those of other treated fruits at the full-ripe stage. Single-layer bagged fruit showed the highest level of gamma-decalactone, a main characteristic aroma of peach and total lactones at the firm-ripe and full-ripe stages. It was concluded that 'Hujingmilu' peach had high quality with abundant aromas when the fruits were bagged with single-layer orange paper bags at 50 DAFB. The biosynthesis of gamma-decalactone and other aromas may be affected by light to some extent.

Chromatography, Gas↗

PubMed2002

Studies on water transport through the sweet cherry fruit surface: III. Conductance of the cuticle in relation to fruit size.

Rain-cracking of sweet cherry fruit has been related to water absorption through the fruit surface and large fruit has been reported to be more susceptible to cracking than small fruit. Therefore, the effect of fruit size on water conductance of the cuticular membrane (CM) of exocarp segments excised from cheek, suture or stylar end region of mature sweet cherry fruit (Prunus avium L. cv. Sam) was investigated. Segments consisting of epidermis, hypodermis and several layers of mesocarp cells were mounted in diffusion cells filled with deionized water. Mass loss due to transpiration was monitored gravimetrically during an 8-h incubation period (25 +/- 2 degrees C) over dry silica in the dark. Conductance was calculated from the amount of water transpired per unit surface area and time divided by the difference in water vapour concentration across the segment. For an average size cv. Sam sweet cherry CM conductance was 1.06 x 10-4, 0.91 x 10-4 and 2.09 x 10-4 m s-1 in cheek, suture and stylar end region, respectively. Fruit size had no significant effect on conductance in cheek or suture regions, but for the stylar end region conductance was positively related to fruit size. Stomatal density in the cheek, but not the suture or stylar end region increased as fruit size increased. The area of the stylar scar was positively related to fruit size. Conductance of the stylar scar averaged 37.6 +/- 4.0 x 10-4 m s-1 and was 54-fold higher than that of the CM between stomata in the cheek region (mean 0.69 x 10-4 m s-1). Conductance calculated on a whole fruit basis is estimated to increase by 108% as fruit size increases from 6 to 12 g. Increased conductance on a whole fruit basis may be attributed to increased fruit surface area and increased conductance per unit fruit surface area, particularly in the stylar end region.

Journal Article↗

PubMed2004

Analysis of the tomato fruit growth response to temperature and plant fruit load in relation to cell division, cell expansion and DNA endoreduplication.

BACKGROUND AND AIMS: To better understand the regulation of fruit growth in response to environmental factors, the effects of temperature and plant fruit load on cell number, cell size and DNA endoreduplication were analysed. METHODS: Plants were grown at 20/20 degrees C, 25/25 degrees C and 25/20 degrees C day/night temperatures, and inflorescences were pruned to two ('2F') or five ('5F') flowers. KEY RESULTS AND CONCLUSIONS: Despite a lower fruit growth rate at 20/20 degrees C, temperature did not affect final fruit size because of the compensation between cell number and size. The higher cell number at 20/20 degrees C (9.0 x 10(6) against 7.9 x 10(6) at 25/25 degrees C and 7.7 x 10(6) at 25/20 degrees C) resulted from an extended period of cell division, and the smaller cell size was due to a shorter period of expansion rather than a lower expansion rate. By contrast, the lower fruit growth rate and size of 5F fruits compared with 2F fruits resulted from the slow down of cell expansion, whereas the number of cells was hardly affected in the proximal fruit. However, within the inflorescence the decreasing gradient of fruit size from proximal to distal fruits was due to a decrease in cell number with similar cell size. Fruit size variations within each treatment were always positively correlated to variations in cell number, but not in cell size. Negative correlations between cell size and cell number suggested that cells of tomato pericarp can be seen as a population of competing sinks. Mean ploidy was slightly delayed and reduced in 5F fruits compared with 2F fruits. It was highest at 25/25 degrees C and lowest at 25/20 degrees C. Treatments did not affect ploidy and cell size in similar ways, but within each treatment, positive correlations existed between mean ploidy and cell size, though significant only in the 2F-25/20 treatment.

Carbon↗

PubMed2001

Variation in surface conductance to water vapor diffusion in peach fruit and its effects on fruit growth assessed by a simulation model.

Surface conductance to water vapor diffusion was measured in individual peach fruits (Prunus persica (L.) Batsch) and plotted as a function of fresh fruit mass for four cultivars. Surface conductance increased with fresh fruit mass, but the pattern differed with cultivar, and fruit-to-fruit variation occurred. Relationships between fruit mass and surface conductance were modeled by fitting mathematical equations to the data. The simulation model of Fishman and Génard (1998) was used to study dry mass and water components of fruit growth (1) when surface conductance varied with fruit size or was constant, and (2) when surface conductance values were high, moderate or low with respect to fruit mass. Increased surface conductance with fresh fruit mass resulted in fruit growth cessation. Fruits differing in surface conductance had similar dry mass. However, under well-watered conditions (stem water potential between -1 and -0.2 MPa), the water balance components of growth (osmotic and hydrostatic pressure, water potential and water balance) differed greatly and, as a result, the lower the surface conductance the greater the fresh fruit mass. These differences were buffered under drought conditions (stem water potential between -2.4 and -0.6 MPa).

Fruit↗

PubMed2006

Mitigation of effects of extreme drought during stage III of peach fruit development by summer pruning and fruit thinning.

A water deficit during stage III of fruit growth was established with the aim of determining if it is possible to achieve an improvement in tree water status by summer pruning and fruit thinning. The experiment was set up as a randomized block split-plot design across trials (irrigation) where pruning was assigned to the main plot and fruit thinning to the sub-plots. The irrigation treatments were (1) standard full irrigation (FI), and (2) suppression of irrigation during stage III of fruit growth until leaves visibly withered (LWI); the pruning treatments were (1) experimental summer pruning (EP), and (2) standard summer pruning (CP); and three fruit thinning intensities were applied to facilitate analysis of the effects of the treatments in relation to fruit load. Changes in amount of light intercepted and in tree stem water potential (Psi stem) were evaluated. The EP treatment reduced the amount of light intercepted by the tree. In the FI treatment, there was a significant reduction in fruit growth measured as both water accumulation and dry mass accumulation. Under FI conditions, reductions in fruit load as a result of EP were not accompanied by a significant improvement in Psi stem. In the LWI treatment, EP produced a significant improvement of 0.17 MPa in Psi stem, but there was no improvement in fruit growth compared with CP trees. A reduction in fruit load from 350 (commercial load) to 150 per tree significantly improved Psi stem by 0.3 MPa at the end of stage III of fruit growth. These results indicate that improvements in water status in response to pruning may be insufficient to promote fruit growth if the pruned trees are unable to provide an adequate supply of assimilates to the developing fruits.

Disasters↗