Journal of Horticultural Science and Biotechnology

Published by Journal of Horticultural Science and Biotechnology
Online ISSN: 1462-0316
Publications
Root (closed circle), shank (open circle) and stem (closed triangle) biomass of Fuji/M.26 apple trees at the end of the first growing season fertigated with different N concentrations twice a week from June to August. Bars on each data point represent standard errors of mean of five replicates.
Nitrogen concentration in stem (closed circle), shank (open circle) and root (closed triangle) at dormant stage of Fuji/M.26 apple trees fertigated with different N concentrations twice a week from June to August. Bars on each data point represent standard errors of the mean of five replicates.
Article
Nitrogen (N) uptake, soil retention and loss of soil-applied N were studied in young apple trees with different N backgrounds. Bench-graft potted Fuji/M.26 (Malus domestica Borkh) trees were fertigated with 5, 10 or 20 mM N twice a week from June to August, and the trees were removed from soil and bare-root stored in a 2°C cold room in December of the first season. In April of the second season, the trees were washed and replanted in containers with a N-free medium (perlite:vermiculite=l:l v), and received 500 ml Hoagland's nutrient solution without N weekly through the experiment. The trees received 15NH4 15NO3 at 1g per plant or no N on June 21. Four trees from each treatment were harvested at one, two and four weeks after 15N application, and 15N and total N in plant tissues and soil were analysed. N fertigation rates during the first growing season increased tree growth and N reserve levels, and N content in trees in the second year. New shoot and leaf growth in the following season was positively related to reserve N. 15N uptake increased during the four weeks after 15N application while soil 15N retention decreased. There was no significant difference in the total 15N uptake per tree. However, trees with the lowest N contents at the end of the first growing season had the highest rate of 15N uptake per unit root dry weight. Four weeks after application of 15N, tree uptake of N accounted for about 60% of applied 15N, while about 20% of the N still remained in the soil, and another 20% of the N was lost. Our results suggested that trees with lower N status are more efficient in N uptake from soil.
 
Article
Levels of abortion of reproductive organs (i.e., buds, flowers, and young fruits) in sweet pepper plants (Capsicum annuum L.) are high, and cyclical fluctuations occur in fruit set. Stages susceptible to abortion are very young buds (< 2.5 mm), buds close to anthesis, and flowers and fruits up to 14 d after anthesis. An overview of factors and processes involved in flower and fruit abortion in sweet peppers is presented. More light, higher CO2 concentrations, and lower planting density, increase the availability of assimilates per plant, and decrease fruit abortion. The cyclical pattern in fruit set is caused by changes in demand for assimilates. High flower abortion occurs when fast growing fruit (at approx. 3 weeks after anthesis) are present, due to competition for assimilates. Fruit set increases when fast growing fruit are almost mature and have a low assimilate demand. Prior to abortion, auxin export from the reproductive organ diminishes, ethylene production increases, and lower levels of activity of sucrose-cleaving enzymes are found. Severe water stress and low nutrient supply also increase abortion levels. Low night- and high day-time temperatures hamper pollen development, causing low seed set, which can result in fruit abortion. Two theories have been used to explain abortion: unbalanced demand for and supply of assimilates, and hormonal dominance of developing fruit over young fruit. Attempts to prevent abortion or to diminish the cyclical pattern of fruit set have not yet been successful, but new suggestions are presented.
 
Article
Abscisic acid (ABA) treatment can confer chilling tolerance upon certain plant tissues that suffer injury at low temperatures. The present study investigated the efficacy of two post-harvest ABA treatments in suppressing low temperature injury (LTI) in cut rose (Rosa hybrida L.) flowers stored at 1°C or 5°C. A shortened vase-life was recorded for roses stored at 5°C compared to untreated roses and those stored at 1°C. Storage at 1°C significantly (P ≤ 0.01) increased electrolyte leakage in 'Akito' roses compared to roses stored at 5°C, or to untreated roses. Storage of 'First Red' and 'Akito' roses at 1°C or 5°C significantly (P ≤ 0.01) increased the malondialdehyde (MDA) contents of petal and leaf tissues. The highest MDA contents were recorded in roses stored at 1°C. ABA at 10 μM as a spray, or at 0.1 M as a pulse treatment, did not affect the MDA contents of either leaves or petals. When averaged over the two storage temperature treatments, the ABA content was highest in roses pulse-treated with 0.1 M ABA, followed by those sprayed with 10 μM ABA, then by untreated (control) roses. However, this increase did not have any apparent effect on the longevity or senescence of the cut roses. Moreover, this trend was inconsistent across all storage treatments. Pulsing with 0.1 M ABA or spraying with 10 μM ABA before storage did not significantly (P > 0.05) affect vase-life. However, pulsing 'Akito' roses with 0.1 M ABA before storage tended to reduce the level of electrolyte leakage from leaves.
 
Article
Post-harvest application of abscisic acid (ABA) can induce stomatal closure in the leaves of cut flower and foliage crops.This effect may be helpful in reducing water deficit stress. Acacia holosericea, a novel cut-foliage line with a short vase-life, was subjected to ABA treatments applied by dipping, pulsing, or in-vase solution, with a view to improving its water balance and extending its longevity. In the first of four experiments, cut single Acacia phyllodes (leaves) were dipped into 0.1, 1.0, or 10.0 mg l-1ABA for 60 s. In the second experiment, phyllodes were pulsed with these same ABA concentrations for 24 h at 20° ± 2°C. In the third experiment, ABA, at the same concentrations, was supplied to phyllodes as a vase solution. In the fourth experiment, cut Acacia whole stems were either dipped in 0.1 mg l-1 ABA solution, pulsed in 0.1 or 1.0 mg l-1 ABA, or stood in 0.01 or 0.10 mg l-1 ABA as vase solutions. Certain ABA dipping and pulsing treatments extended the vase-life of cut phyllodes by up to approx. 1.8-fold and 1.5-fold, respectively. Moreover, the application of ABA as a pulse or vase solution could reduce the uptake of vase solution by cut phyllodes, suggesting the induction of stomatal closure. Lower concentration ABA dip (1.0 mg l-1) and pulse (0.1 mg l-1) treatments extended the longevity of phyllodes, but high ABA dip and pulse concentrations (10.0 mg l-1) were ineffective.ABA in the vase solution at 0.01 mg l-1 extended the vase-life of cut stems, but did not reduce the uptake of vase solution. Overall, despite some vase-life and water balance benefits, post-harvest ABA treatments were not of value for cut A. holosericea foliage stems because of their inconsistent effects.
 
Article
Abscisic acid (ABA) supplied in the vase solution can induce stomatal closure in the leaves of cut flowers, including roses (Rosa hybrida L.). This effect may be beneficial in reducing water deficit stress. Extracellular pH can affect active ABA concentrations in the apoplast of guard cells, with sap alkalisation enhancing the physiological activity of ABA. Accordingly, it was hypothesized that vase solution pH may affect ABA-mediated stomatal closure of cut roses. Two experiments were conducted to study the interaction of vase solution pH and ABA. In the first, cut 'Baccara' roses were held in vase solutions with +/- 10(-5) M ABA at pH 6, pH 7 and pH 8. In the second experiment, roses were held with +/- 10(-5) M ABA at pH 6 and pH 8 in the presence and absence of 1 mg l(-1) AgNO3 as a bactericide. Supply of ABA increased vase life and reduced vase solution usage of flowers held in low pH 6 solutions, indicating induction of stomatal closure. Conversely, ABA supplied at pH 8 was associated with reduced vase life. This negative result was associated with enhanced development of vase solution microbes at high pH, which overrode any potential pH-mediated ABA efficacy effects.
 
Article
Exposure to ethylene gas elicits flower abscission from cut stems of Geraldton waxflower (Chamelaucium uncinatum Schauer). Ethylene response rates in plants are mediated by temperature. At 20degreesC, flower abscission from waxflower 'Purple Pride' occurred upon 12 h exposure to I mu11(-1) ethylene. This ethylene treatment did not cause flower abscission at either 10 or 2degreesC. Moreover, flowers held at 2degreesC were insensitive to 48 h exposure to 1, 10 and 100 mu11(-1) ethylene. However, increasing the duration of treatment with I mu11(-1) ethylene at 10 and 2degreesC to 48 and 144 h, respectively, induced flower abscission. When flowers were held at 20degreesC in air without exogenous ethylene following continuous exposure to I mu11(-1) ethylene at 2degreesC, the duration required to elicit flower abscission was reduced from 144 to 72 It. Collectively, these responses show that maintaining harvested waxflower at low temperature (e.g. 2degreesC) is an effective means to minimise ethylene-mediated flower abscission.
 
Article
Wilting associated with diminishing post-harvest water uptake is a major constraint on longevity for cut stems of many Acacia spp. Cu2+ ions have known biocidal activity and may also act as inhibitors of plant wound reaction enzymes. A series of experiments were conducted using Cu2+ ions as a pulse, or as a vase-solution additive to evaluate their potential to extend the vase life of cut A. holosericea foliage stems. Provision of Cu2+ ions in the vase-water at 0.5 mM, or as a 5 h pulse at 1.0 mM, resulted in 1.4- to 2.8-fold, and 1.7- to 2.1-fold extensions of vase-life, respectively, compared to de-ionised water controls. The pulse treatment was optimised, and a 5 h pulse with 2.2 mM Cu2+ ions resulted in a 2.6-fold extension of vase-life. Thus, Cu2+-pulsing can effectively delay wilting in cut A. holosericea foliage stems.
 
Article
Differences in environmental conditions are known to influence plant growth and growth-related traits. The aim of this study was to identify the variation in relative growth rate (RGR), and its underlying physiological and morphological traits, in a group of ten wild and cultivated Capsicum accessions of four Capsicum species at two contrasting temperatures. Therefore, a growth analysis was performed at two temperature regimes (21.1°/18.7°C and 17.3°/14.7°C; day/night).Variation in RGR, growth-related traits and their mutual relationships were analysed at the start of branching. RGR at branching proved to be a reliable predictor for the development of dry mass pre-anthesis in Capsicum. The reduction in RGR and growth-related traits, in response to lowered temperatures, varied between these Capsicum accessions; some being better adapted to low temperatures than others.The variation in the reduction of RGR under lowered temperatures was due to changes in both net assimilation rate (NAR) and leaf area ratio (LAR). Dry mass allocation to the leaves (leaf mass fraction) was not influenced by temperature. Specific leaf area (SLA) was correlated with RGR under standard temperatures, but not under lowered temperatures. At both temperatures, NAR was the most important factor to explain variations in RGR between the different Capsicum accessions. From this study, and the work of others, it was concluded that NAR was the most important factor to explain variations in RGR in plants of the same genus or species, and even between closely-related plant species.
 
Relation between leaf width (W) and leaf length (L) of single leaves from four measured Capsicum accessions measured in the calibration experiment. This figure includes the length and width of leaves of all ages and accessions. The lines represent linear regression lines for the different accessions: 'Jatilaba' (L = 2.7·W; R 2 = 0.94), 'Bruinsma Wonder' (L = 1.76·W; R 2 = 0.97), F 1 ('Jatilaba' 'Bruinsma Wonder') (L = 2.27·W; R 2 = 0.96) and 'Nassau' (L = l .74·W; R 2 = 0.97).  
Relation between calculated leaf area using (a) Model 1 (R 2 = 0.994; MSE = 5.4) or (b) Model 2 (R = 0.996; MSE= 4.0) and measured area of single leaves from four Capsicum accessions. Data originate from the validation set of the calibration experiment. Solid lines represent the linear regression lines; dotted lines represent the 1:1 relationship. Symbols indicate the different accessions tested.  
Article
Accurate measurements of leaf area are important for agronomic and physiological studies. To be able to perform repeated measurements of leaf area on single (genetically unique) plants, a method was developed to estimate leaf area from non-destructive measurements in Capsicum annuum L. independent of plant age and accession. Leaf length (L), width (W), position (leafno) and area of individual leaves were measured on 160 plants of four Capsicum accessions with different leaf shapes at different plant ages. Leaf area could be predicted from the product of length and width (α.LW), but this model could not account for changes in leaf shape during development of individual leaves and was dependent on both plant age and accession.The model became independent of plant age and accession when leaf width terms (W2, W) were added. Validation on leaves measured in a second experiment containing three accessions and 200 genetically unique F3 plants showed that the relation between calculated and measured area was very high.The model could still be refined by addition of the leaf position terms (R2=0.996). Even when the length and width of only 25␘f the leaves were measured, total plant leaf area was predicted well using the model with both leaf width and leaf position terms.Therefore, the models including the leaf width terms (W2, W) in addition to the LW term are useful tools in physiological research and breeding in Capsicum.
 
Article
Strawberry fruit are susceptible to microbial decay during post-harvest storage. To search for an effective alternative to currently-used fungicides for disease control, we investigated the effect of benzo-(1, 2, 3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) on fruit decay and the maintenance of quality in strawberries after harvest. Freshly harvested strawberry fruit were treated with 0 (control), 0.05, 0.20 or 0.50 g l-1 BTH for 5 min. BTH treatment at 0.20 g l-1 was most effective at inhibiting fruit decay in strawberry fruit during storage at 5°C, while quality parameters such as total soluble solids contents and titratable acidity were also maintained. Fruit treated with 0.20 g l-1 BTH exhibited reduced microbial populations and higher activities of chitinase and β-1,3-glucanase. However, treatment with 0.50 g l-1 BTH was ineffective at controlling fruit decay. Our results show that a post-harvest application of an appropriate concentration of BTH treatment was effective in reducing fruit decay and enhanced disease resistance in strawberry fruit. The data obtained suggest that BTH may provide an alternative to control post-harvest decay in strawberry fruit.
 
Article
The observation that the wild, red fruited tomato Lycopersicon pimpinellifolium has higher soluble solids than the cultivated variety L. esculentum may be related to differential controls on fruit carbohydrate metabolism. We therefore investigated the role of acid invertase (AI) in determining fruit sugar composition in these two species. At all stages of fruit development, the majority of AI was localized in the vacuole with about 10&percent; of the total activity in the extra-cellular space. Four forms of soluble AI activity were identified. Isoform 1 persisted throughout development. Isoform 2 showed a strong relationship to total fruit sugar content in both species, suggesting that this isoform is the tiv1 gene product located in the vacuole, and that it plays a major role in determining fruit soluble solids. Isoform 3 was very high in L. pimpinellfolium but not in L. esculentum. We suggest that AI has a major role in determining fruit sugar accumulation in L. pimpinellifolium, but not in L. esculentum. Pulse-chase in vitro unloading experiments with [3h]-glucose showed that a substantial amount of [3h]-sucrose was present in the apoplast, suggesting an exchange of sugars between extra- and intra-cellular spaces. Hence ``futile cycles'' of sucrose synthesis and degradation involving apoplastic AI can occur during fruit development.
 
Article
Compounds that activate host plant defence responses potentially offer socio-environmentally sound alternative methods for disease control. In a series of glasshouse trials over 2 years, pre-harvest sprays with acibenzolar-S-methyl (ASM) and methyl jasmonate (MeJA) were tested for suppression of post-harvest infection of cut Freesia hybrida L. flowers by Botrytis cinerea. For the ASM treatments, variability in reducing the incidence of B. cinerea disease was observed between years freesia varieties, incubation temperatures and ASM concentrations. In the first year, the greatest reductions in lesion numbers on ASM-treated var. 'Cote d'Azur' were recorded using 2.86 mM ASM. For three different post-harvest temperature regimes, the relative reductions in lesion numbers, compared to untreated controls, were 45% at 5 degrees C, 40% at 12 degrees C and 30% at 20 degrees C, respectively. In the second year, lesion numbers were most reduced using 1.43 mM ASM to treat freesia var. 'Dukaat' flowers. Here, the relative reductions were to 44% at 5 degrees C, 26% at 12 degrees C and 51% at 20 degrees C. MeJA treatments were, in general, more consistently effective than ASM treatments in reducing lesion numbers and lesion diameters on cut freesia flowers. MeJA-treated (0.2 mM) freesia flowers (var. 'Dukaat') incubated at 20 degrees C showed relative reductions of 62%, and 45% for lesion number and lesion diameter, respectively. The differing efficacy between ASM and MeJA treatments could be attributed to their differential abilities to induce the salicylic acid (SA)-mediated vs. the jasmonic acid (JA)-mediated host defence pathways, respectively.
 
Article
Scions from two siblings of a 'Goldspur Delicious' x '`Redspur Delicious' cross were budded to three rootstocks with different levels of vigour [M.9, M.7, and Malus domestica 'Antanovka' seedling] and planted in the field in 1997. The scions had two contrasting growth habits: one with narrow crotch angles, numerous short branches and an upright narrow (UN) canopy; and the other with wide crotch angles, few short branches, and a spreading round (SR) canopy. Shoot tips were collected at the time of bud-break in April 2004 and analysed for auxin (AUX), cytokinins (CK), and abscisic acid (ABA) to determine relationships between scion growth habit, size-controlling rootstock, and shoot tip hormone concentrations. Although not statistically different, the UN growth habit had numerically higher AUX, lower ABA, and equivalent CK levels as the SR growth habit. These differences resulted in statistically higher AUX:CK ratios (ACR). It is possible that the higher ACR contributed to the UN growth habit, which had more anti-gravitrophic shoot growth and appeared to have greater apical dominance than the SR growth habit. Either growth habit, grown on seedling rootstock, had nearly twice the ACR than on M.7 or M.9 rootstocks. The synthetic CK, 6-benzyl adenine (BA), was applied to 30 cm shoot explants of both growth habits in a greenhouse in March 2006. An 8.7 mM BA concentration stimulated bud-break in both growth habits, compared with controls, and bud-break was increased more in the UN than the SR growth habit. The results indicate that the ACR may be a factor regulating bud-break and the development of growth habit in apple scions, and that rootstock modified the hormone concentrations in shoot tips.
 
Article
The aim of this study was the identification of those product characteristics that are important for the adoption of fruit and fruit product innovations by consumers. Sixteen focus group discussions were held in four European countries (Greece, The Netherlands, Poland, and Spain). Different aspects of six innovative fruit products were discussed, revealing those characteristics that were important for the adoption of each of them. It was observed that the participants did not perceive fruit innovations as a homogenous group, but assigned them to different groups, which led to a number of categories of fruit innovation. Three categories concerned the level of preparation of fruit. These were fresh, prepared, and processed fruit product innovations. Another two categories, radical and evolutionary innovations, related to the level of novelty of the fruit innovation. Characteristics important for the adoption of each of these categories are given.The results will be used for further, more quantitative, research.
 
Article
Backhousia citriodora is typical of the many commercially valuable woody Australian Myrtaceae species that are recalcitrant in forming adventitious roots from cuttings after maturation. A series of experiments were conducted to identify an endogenous rooting inhibitor in line with established criteria. Endogenous levels of citral were correlated with the rooting capacities of juvenile versus mature, and easy- versus difficult-to-root genotypes of B. citriodora, in both winter and summer. The biological activity of citral was confirmed in bioassays on mung beans and easy-to-root B. citriodora seedlings. Evidence of a common mechanism of root inhibition with other species in the Myrtaceae and the role of action of citral are discussed.
 
Article
The hypothesis that water flow into tomato fruits is affected similarly by osmotic potential of the nutrient solution and potential transpiration (shoot environment) via their effects on stem water potential, was tested through experiments carried out in two glasshouses where climate was controlled to maintain a desired potential transpiration rate (normal and depressed, respectively). This climate treatment was factorially combined with a root zone osmotic potential treatment, whereby two values of osmotic potential were compared in each experiment. Data showed that water uptake per unit leaf area was not affected by osmotic potential of the nutrient solution. The hydraulic resistance within the plant, deduced from measurements of leaf and stem water potential, was independent of the transpiration flow and was not affected by the osmotic potential of the nutrient solution. Water import into the fruit was affected by both treatments and was correlated with the water potential gradient between the stem and the fruit. Since fruit osmotic potential was relatively constant at a given concentration of the nutrient solution, the stem water potential appeared to be a good indicator of fruit growth rate.
 
Article
The cracking of bell pepper fruit is one of the main physiological disorders that reduce marketable yield. Understanding the environmental and endogenous factors that influence this disorder may help to reduce its severity. Plants grown in three greenhouses were subjected to differing potential transpiration (Tp) at night, with identical daytime Tp. Measurements included climatic variables in the greenhouses, soil water content, sap flow, transpiration, leaf temperature, surface and internal fruit temperatures, fruit and stem diameters, stomatal conductance, and leaf area. The results show that at night pepper plants transpired at a rate proportional to the vapour pressure difference (leaves to air; VDP(1a)) in the respective greenhouses. The percentage of cracked fruits was highest in the greenhouse with the lowest night vapour pressure deficit (VPD) and lowest in the greenhouse with the highest VPD. Both increased direct radiation reaching the fruit surface and decreased soil water content reduced the growth rate of the fruit. Direct radiation and the temperature of the fruit inner space were well correlated with diurnal expansion and shrinkage of the fruit. The fruits with the higher expansion-shrinkage amplitude had more severe cracking symptoms. Decreased soil water potential counteracted the negative effect of direct radiation. These results indicate that the water status of the fruit is a key factor in determining the severity of fruit cracking. The implications of these results for greenhouse management in pepper production are discussed.
 
Percentage of flower buds per plant of Chrysanthemum morifolium cv. 'Reagan Improved' as a function of the interaction between temperatures during: (A) phases I and II; (B) phases II and III. Overall regression model for the transformed data: y = – 2.76 + 0.0564T I + 0.121T II + 0.0761T III – 0.00287T I T II – 0.00156T II T III ; R 2 = 0.76. Symbols represent temperatures applied during: (A) phase I: 18°C; 24°C; and (B) phase III: 15°C; 18°C; 21°C; 24°C. Vertical bars indicate LSD = 7.3 (A) and LSD = 10.4 (B) using transformed data (arcsine square root transformation).  
Individual flower dry mass (A) and individual flower area (B) of Chrysanthemum morifolium cv. 'Reagan Improved' as a function of temperature during phase II and phase III. Overall regression models: (A) y = 0.42 + 0.0055T II – 0.0262T III + 0.00052T III 2 ; R 2 = 0.70; (B) y = – 0.10 + 0.57T II + 2.54T III – 0.087T III 2 ; R 2 = 0.77. Vertical bars indicate LSD = 0.012 (A) and LSD = 1.6 (B).  
Article
The sensitivity to temperature of the number of flowers per plant including flower buds (NFPP), flower size, position and colour was investigated in cut chrysanthemum (Chrysanthemum morifolium cv. `Reagan Improved¿). Plants were grown either in a glasshouse at constant 24 h mean temperatures throughout cultivation (17°C or 21°C), or in growth chambers at 32 different temperature combinations (from 15°C to 24°C). The latter temperature combinations were applied by dividing the cultivation period into three sequential phases: long-day period (phase I), start of short-day period to visible terminal flower bud (phase II), and end of phase II to harvest stage (phase III). All flower characteristics were affected significantly by temperature, except for flower position within the plant. Higher temperatures increased NFPP, mainly by increasing the number of flower buds, but decreased individual flower size. The temperature effect was also dependent on the phase of the cultivation period. In general, flower characteristics were less sensitive to temperature applied during the long-day period. NFPP was affected positively by temperature, mainly during phase III, whereas individual flower size increased with temperature during phase II, but decreased with temperature during phase III. Lower temperatures during phase III significantly enhanced flower colour intensity. Interest in using a more dynamic heating strategy is discussed
 
Article
Tomato plants (Lycopersicon esculentum Mill. 'DRK') were grown hydroponically in two experiments to determine the effects of nutrient concentration and distribution in the root zone on yield, quality and blossom end rot (BER). The plants were grown in rockwool with their root systems divided into two portions. Each portion was irrigated with nutrient solutions with either the same or different electrical conductivity (EC) in the range 0 to 6 dS m(-1). In both experiments, fruit yields decreased as EC increased from moderate to high when solutions of equal concentration were applied to both portions of the root system. However, higher yields were obtained when a solution with high EC was applied to one portion of the root system and a solution of low EC to the other portion. For example, the fresh weight of mature fruits in the 6/6 treatment was only 20% that of the 3/3 treatment but the 6/0 treatment had a yield that was 40% higher. The reduction in yield in the high EC treatments was due to an increase in the number of fruits with BER and smaller fruit size. BER increased from 12% to 88% of total fruits as EC increased from 6/0 to 6/6 and fruit length decreased from 67 mm to 52 mm. Fruit quality (expressed as titratable acidity and soluble solids) increased as EC increased. In summary, high yields of high quality tomatoes with minimal incidence of BER were obtained when one portion of the root system was supplied with a solution of high EC and the other portion with a solution of moderate or zero EC.
 
Effects of nitrogen [N] fertigation during the growing season and foliar urea application in the fall on concentrations of free (A) and total amino acids (B), and the ratio of protein N to free amino acid N (C) of young almond trees. Each value is the mean of five replicates. Error bars represent standard errors of the mean for each treatment. F = N fertigation, and F + U = N fertigation and foliar urea treatments.
Effects of nitrogen [N] fertigation during the growing season and foliar urea application in the fall on the ratio of nitrogen in free arginine to that in free amino acids (A), and the ratio of nitrogen in total arginine to that in total amino acids (B) of young almond trees. Each value is the mean of five replicates. Error bars represent the standard errors of the mean for each treatment. F = N fertigation, and F+U = N fertigation and foliar urea treatments.
Effects of nitrogen [N] fertigation during the growing season and foliar urea application in the fall on molar Carbon/Nitrogen [C/N] ratio in free (A) and total amino acids (B) from young almond trees. Each value is the mean of five replicates. Error bars represent the standard errors of the mean for each treatment. F = N fertigation, and F+U = N fertigation and foliar urea treatments.  
Effects of nitrogen [N] fertigation during the growing season and foliar urea application in the fall on the concentrations (mg g-1 DW) of glucose (A), fructose (B), sucrose (C), sorbitol (D), starch (E), and TNC [total non-structural carbohydrates] (F) from young almond trees. Each value is the mean of five replicates. Error bars represent the standard errors of the mean for each treatment. F = N fertigation, and F+U = N fertigation and foliar urea treatments.
Concentrations of non-structural carbohydrates (TNC) in relation to concentrations of total amino acids from young almond trees. Regression equation: Y = 243.58 -1.964X (r 2 = 0.66, P<0.0001). F = N fertigation, and F+U = N fertigation and foliar urea treatments.  
Article
June-budded 'Nonpareil/Nemaguard' almond (Prunus dulcis (Mill) D. A.Webb) trees were fertigated with one of five nitrogen (N) concentrations (0, 5, 10, 15, or 20 mM) in a modified Hoagland's solution from July to September. In October, the trees were sprayed twice with either water or 3% urea, then harvested after natural leaf fall and stored at 2°C. Trees were destructively sampled during winter storage to determine their concentrations of amino acids, protein, and non-structural carbohydrates (TNC). Increasing N supply either via N fertigation during the growing season or with foliar urea applications in the fall increased the concentrations of both free and total amino acids, but decreased their C/N ratios. Moreover, as the N supply increased, the proportion of nitrogen stored as free amino acids also increased. However, protein was still the main form of N used for storage. The predominant amino acid in both the free and the total amino-acid pools was arginine. Arginine N accounted for an increasing proportion of the total N in both the free and the total amino acids as the nitrogen supply was increased. However, the proportion of arginine N was higher in the free amino acids than in the total amino acids. A negative relationship was found between total amino acid and non-structural carbohydrate concentrations, suggesting that TNC is increasingly used for N assimilation as the supply of nitrogen increases. Urea applications decreased the concentrations of glucose, fructose, and sucrose, but had little influence on concentrations of sorbitol and starch.We conclude that protein is the primary form of storage N, and that arginine is the predominant amino acid. Furthermore, the synthesis of amino acids and proteins comes at the expense of non-structural carbohydrates.
 
Average 15 N uptake rate of young Fuji/M.9 apple trees 10 d after 15 N-urea was applied either to the foliage (white) or through the soil (gray) at different times of the season. Bars on each column represent standard errors of the mean of five replicates. Columns with the same letter above them are not significantly different (LSD, P ≤ 0.05). May Jul Sep
The percentage of 15 N in major organs (A-C) of Fuji/M.9 apple trees 10 d after 15 N-urea was applied either to the foliage (white) or through the soil (gray) at different times of the season. Bars on each column represent standard errors of the mean of five replicates. Columns with the same letter above them are not significantly different (LSD, P ≤ 0.05).
Article
Leaf and root nitrogen (N) uptake was compared at different times of the season in young apple trees. One-year-old potted Fuji/M.9 trees were supplied with 1% 15N-labelled urea either by foliar or soil applications in May, July and September. Trees receiving only water served as controls. The trees were harvested 10 d after 15N application, separated into shoots (leaves and current-year stems), stem (previous-year wood) and roots. Biomass, total N and 15N contents of all tissues were determined. New shoot biomass and total tree biomass increased as the season advanced, while root biomass peaked in July. Leaf N uptake was higher than root uptake in May and September, while root N uptake was higher than leaf uptake in July. Leaf N uptake increased as the season advanced, while root N uptake was highest in July. The lowest 15N recovery (11%) was obtained in May with soil N application, and the highest 15N recovery (48%) was obtained in September with foliar N application. Our results suggest that foliar application of N early in the season, followed by soil N application in mid-season, then foliar application again late in the season is an efficient N management strategy for young trees.
 
Article
Uniformly mature green 'Delta R2E2' mangoes were stored at 13° ± 1°C in normal air (control) or in controlled atmosphere (CA) chambers containing combinations of three concentrations of O2 (1.5%, 2% or 3%) and two levels of CO2 (6% or 8%) to investigate the effects of CA-storage on the biosynthesis of aroma volatile compounds in ripe fruit. Fruit were removed after 24 d and 38 d of storage and ripened at 21° ± 1°C. CA-storage of fruit for 24 d in 6% CO2 significantly reduced the total concentrations of aroma volatile compounds and monoterpenes. However, increased O2, in combination with 8% CO2 in CA-storage significantly increased most of the individual monoterpenes including α-terpinolene (the most abundant terpene). All CA treatments significantly reduced total sesquiterpene levels compared to air-stored fruit irrespective of the storage period. Increased concentrations of O2 (1.5% to 3%), in combination with 6% and 8% CO2 in CA-storage, increased the production of sesquiterpenes in the pulp of ripe fruit and the trend was more pronounced in fruit stored for 24 d. Fruit stored in a CA of 1.5% O2 and 8% CO2 for 24 d resulted in significantly higher levels of ρ-cymen-8-ol; however, after 38 d of storage, levels of this compound were significantly higher in fruit stored in 3% O2 and 6% CO2, compared to all other CA treatments. Levels of acetic acid and β-ionone were high in ripe fruit stored under normal conditions for 24 d. After 38 d of storage, acetic acid was higher in fruit stored in a CA of 1.5% O2 and 8% CO2. Ethanol, acetaldehyde and esters were significantly higher in fruit stored in CAs of 1.5% O2 and 6% CO2, as well as in 1.5% or 2% O2 in combination with 8% CO2, compared to all other treatments. CA-storage for up to 38 d in 6% CO2 and 3% O2 appears promising for 'Delta R2E2' mango, without causing significant fermentation products, especially ethanol and acetaldehyde.
 
The principal "House of Quality" used by ISAFRUIT for the "Vasco da Gama" process
Article
The goal of ISAFRUIT to increase fruit consumption has strong foundations in the new knowledge created by a multidisciplinary team of natural and social scientists addressing critical aspects of the multi-faceted fruit chain. Bridging the gap between disciplines proved to be a substantial challenge, as they have quite different languages, methods, and networks. In March 2008, ISAFRUIT launched an initiative to address this gap and named it the “Vasco da Gama process”, after the Portuguese explorer who, early in the 16th century, embarked in the first ships to sail directly from Europe to India and to bridge the gap between continents and cultures. ISAFRUIT’s process for bridging between research disciplines was to discover if the research conducted indeed contributed to increased fruit consumption in Europe. For this purpose, the Quality Function Deployment (QFD) method was applied. This includes the construction of a House of Quality (HoQ), which is a conceptual and graphical tool that presents the positive and negative relationships between technical quality traits, as studied and influenced by pre- and post-harvest experiments, and consumer-demand terms. This paper explains the methodology in greater detail. The first experience with this process showed that, even if scientists from different disciplines were keen to be involved, there was a need for a sustained effort to drive such a process. The process is still underway, and specific results will be published later
 
The principal "House of Quality" used by ISAFRUIT for the "Vasco da Gama" process 
Article
The goal of ISAFRUIT to increase fruit consumption has strong foundations in the new knowledge created by a multidisciplinary team of natural and social scientists addressing critical aspects of the multi-faceted fruit chain. Bridging the gap between disciplines proved to be a substantial challenge, as they have quite different languages, methods, and networks. In March 2008, ISAFRUIT launched an initiative to address this gap and named it the “Vasco da Gama process”, after the Portuguese explorer who, early in the 16th century, embarked in the first ships to sail directly from Europe to India and to bridge the gap between continents and cultures. ISAFRUIT’s process for bridging between research disciplines was to discover if the research conducted indeed contributed to increased fruit consumption in Europe. For this purpose, the Quality Function Deployment (QFD) method was applied. This includes the construction of a House of Quality (HoQ), which is a conceptual and graphical tool that presents the positive and negative relationships between technical quality traits, as studied and influenced by pre- and post-harvest experiments, and consumer-demand terms. This paper explains the methodology in greater detail. The first experience with this process showed that, even if scientists from different disciplines were keen to be involved, there was a need for a sustained effort to drive such a process. The process is still underway, and specific results will be published later
 
Illustration of grafting in 'Elstar' apple (scion) with M.9 rootstock. 'Elstar' apple GM line TJ1 scion (1). The top of the M.9 rootstock was cut-off immediately above the graft union (2). The graft union (3). The 'Elstar' GM scion was cut free from its own root 1-2 cm below the graft union (4). The rooted 'Elstar' GM TJ1 line, with a new lateral shoot, could be used again for a new grafting on the same rootstock, if the first grafting failed (5). The M.9 rootstock (6). Pot diameter 18 cm. 
Real-time quantitative PCR amplification plot showing the amount of 18S rRNA and Mal d 1 mRNA in leaves of selected GM 'Elstar' apple lines. Mal d 1 EL was the non-GM-EL control. 18S rRNA was the endogenous control. Mal d 1 lines TM1 and TL1 were moderately silenced GM-lines. Mal d 1 lines TB, TG, TI, TJ, and TK were efficiently silenced GM-lines. 
Article
Many people who are allergic to birch pollen are also allergic to apple fruit, due to cross- allergenicity. Since apples are the most extensively consumed fruit in Europe, it is highly relevant to develop a hypo-allergenic apple. Apples with significantly reduced levels of the allergen, Mal d 1, may allow many apple allergics to eat them without an allergic reaction. We are currently collaborating to develop a hypo-allergenic apple within the European Integrated Research Project, ISAFRUIT (www.isafruit.org). Hypo-allergenic apple plants (Malus × domestica Borkh., ‘Elstar’) with decreased levels of Mal d 1 mRNA were produced by RNA interference (RNAi) technology. Ten genetically modified (GM) apple lines were selected. In vitro plantlets were first transferred to a greenhouse, then grafted onto wild-type M.9 rootstock to promote the development of fruit-producing trees. Levels of Mal d 1 gene silencing were measured repeatedly by quantitative real-time PCR. Compared to leaf samples from wild-type ‘Elstar’, two GM lines showed modest levels of gene silencing (up to 250-fold), whereas the other eight GM lines were significantly silenced (up to10,000-fold) in Mal d 1 gene expression. These levels of silencing were unaffected by grafting, and have been stable over more than 3 years, and throughout all developmental stages.
 
Total tree dry weight (A) and change in total tree dry weight (B) of young almond trees fertigated with nitrogen (N) (+N) or without N (–N) in the spring. Each data point represents the least squares mean; error bars are SEs of the mean of five replicates.  
Dry weight of leaves (A), new shoots (B), roots (C), and stems (D) of young almond trees fertigated with nitrogen (N) (+N) or without N (–N) in the spring. Each data point represents the least squares mean; error bars are SEs of the mean of five replicates.  
Distribution of 15 N in leaves, stems, new shoots and roots following 15 N fertigation of young almond trees in the spring. Each data point represents the least squares mean; error bars are SEs of the mean of five replicates.  
N content of leaves (A), new shoots (B), roots (C), and stems (D) of young almond trees fertigated with nitrogen (N) (+N) or without N (-N) in the spring. Each data point represents the least squares mean; error bars are SEs of the mean of five replicates. +N ( 15 N uptake) = total-15 N content in trees that were fertigated with N. +N (Reserve) = difference between the total-N and labelled-15 N contents in trees that were fertigated with N (=reserve N remobilized in N-fertigated plants).
Article
One year old 'Nonpareil' almond (Prunus dulcis (Mill) D.A.Webb) trees on 'Lovell' rootstocks were used to evaluate the effects of soil nitrogen (N) availability in the spring on N remobilization, uptake, partitioning, and tree growth. After being transplanted to an N-free medium, the trees received a modified Hoagland solution, with or without N from 15N-depleted NH4NO3, twice a week for 12 weeks. During the first four weeks, the N used for new shoot and leaf growth mainly came from the nitrogen that had accumulated in storage tissues. No significant differences were seen in the amount and duration of N remobilization between N-fertilized trees and those that received no N. However, trees that were fertilized in the spring had significantly more new shoot and leaf growth. Uptake of 15N by the roots began two weeks after transplanting. Nitrogen was rapidly taken up from the soil during the period of greatest shoot and leaf growth; leaves were the major sink for N from both root uptake and storage. Six weeks after transplanting, the whole-tree N content was significantly higher in fertilized trees than in the controls. We conclude that the remobilization of N for spring new growth takes place irrespective of the current-year external N supply. However, the new growth in young almond trees is highly dependent on soil N availability, which demonstrates the importance of spring N fertilizer applications following transplantation.
 
Article
June-budded 'Nonpareil'/'Nemaguard' almond (Prunus dulcis (Mill) D. A. Webb) trees were fertigated with one of five nitrogen (N) concentrations (0, 5, 10, 15, or 20 mM) from July to September. The trees were sprayed with either water or 3&percnt; urea in October, then harvested bareroot after natural leaf fall, and stored at 2°C. One set of trees was destructively sampled for total N content; the remaining trees were transplanted into N-free media in the spring after cold storage. After budbreak, these trees were supplied for 70 d with either N-free Hoagland's solution or Hoagland's solution containing 15N-NH4,NO3. Nitrogen concentrations in both stem and root tissues were positively correlated with the N-fertigation concentration. Fall foliar urea applications increased levels of stem and root N regardless of the N-fertigation concentration. During the first 70 d of spring growth, the trees utilized nitrogen from both their reserves and spring fertilizer applications. The amount of N reserves used for growth of new shoots and leaves was proportional to the total amount of reserves. Trees with low N reserves relied primarily on the spring fertilizer as their source of nitrogen. We conclude, therefore, that both reserve N and spring-applied N fertilizers are important for enhancing the regrowth of bareroot almond nursery trees during establishment after transplanting. Nitrogen fertilization in the spring can especially improve the performance of trees with low N reserves.
 
Article
Two cDNA clones, idi1 and idi2, representing different isoforms of isopentenyl pyrophosphate isomerase (IPP isomerase) were isolated from Melaleuca alternifolia (Cheel) by functional complementation of carotenoid biosynthesis in E. coli.. Excluding the putative transit peptide region, share 89.5% predicted protein sequence identity. The high level of conservation between the isoforms indicates that these genes may share a common ancestral origin and supports the proposition that cytosolic and plastid targeted IPP isomerase may be differentially translated from a single gene. This study supports recent evidence suggesting that isopentenyl pyrophosphate and dimethylallylic pyrophosphate are both immediate products of the deoxyxylulose pathway and that IPP isomerase may have a more central role in the biosynthesis of carotenoids than in the biosynthesis of monoterpenes.
 
Article
We assessed whether adding inoculum of the vesicular-arbuscular mycorrhizal fungus (VAMF) Glomus intraradices into growing medium of three Zephyranthes spp (White Rain Lily [WRL], Z. Candida; Pink Fairy Lily [PFL], Z. robusta; Yellow Zephyr Lily [YZL], Z. sulphurea) alters aspects of flower and bulb production. Shoots of inoculated plants emerged 7-13 d earlier than those of non-inoculated plants. Inoculation slightly delayed the emergence of flower buds on WRL and PFL, but did not delay the time of flower opening of WRL. Inoculated YZL flowered 4-11 d earlier than non-inoculated plants. The number of flowers produced by YZL was consistently increased by inoculation, while the inoculation with VAMF increased flower production by WRL and PFL only when plants were growing in pasteurized soil. Leaf biomass of inoculated WRL was larger than non-inoculated plants, while leaf biomass was generally smaller in inoculated PFL and YZL. Partitioning of biomass to bulbs and offsets varied with species, soil pasteurization, and inoculation. Inoculation increased the combined weight of bulbs and offsets at the end of the second growing cycle by 50-150%. Inoculated YZL and WRL consistently produced more offsets in the second growing season after inoculation. For all species, inoculation increased phosphorus and carbohydrates and decreased nitrogen and amino acids in bulbs. Adding VAMF into the growing medium of Zephyranthes altered aspects of plant development and biomass partitioning important to flower and bulb production during the first growing cycle after inoculation, and most effects of VAMF inoculation are more pronounced in the second growing cycle after inoculation. Of the three species examined, Z. sulphurea showed the most consistent responses to inoculation.
 
Article
One-year-old rhododendron (Rhododendron ‘H-1 P.J.M’) and azalea (Rhododendron ‘Cannon’s Double’) plants grown at different nitrogen (N) fertilisation rates were used to assess the influence of soil N applications during the growing season, and foliar applications of urea in the Autumn, on N uptake and accumulation, and plant growth in the following Spring. N uptake efficiency declined linearly during the first growing season with an increasing rate of N fertilisation. For both cultivars, foliar urea application in the Autumn significantly increased plant N content without affecting plant size, regardless of plant N status. Leaves of rhododendron accumulated more N than other plant structures. Plants sprayed with foliar urea in the Autumn had more new growth the following Spring than plants receiving no urea, regardless of whether the plants received fertiliser in the Spring. For azalea, N uptake in the Spring was, in general, not affected by applications of urea during the previous year. For rhododendron, urea application in the Autumn decreased N uptake the following Spring. For both cultivars, increasing N availability during the growing season increased the ratio of above-ground to below-ground dry weight. Our results suggest that combining optimum N applications during the growing season with foliar application of urea in the Autumn can improve N uptake efficiency, increase N storage, and optimise growth in Rhododendron.
 
Article
Phosphonate fungicides are used widely in the control of diseases caused by Phytophthora cinnamomi Rands. For the most part phosphonate is seen as a safe to use on crops with phytotoxicity rare. However, recent research has shown that phosphonate has detrimental effects on the floral biology of some indigenous Australian plants. Since phosphonate fungicides are regularly used for the control of Phytophthora root rot in avocados, research was carried out to study the translocation of phosphonate fungicide in `Hass' trees and any effects on their floral biology. Field- grown trees were sprayed with 0, 0.06 or 0.12 M mono-dipotassium phosphonate (pH 7.2) at summer flush maturity, floral bud break or anthesis. Following treatment, phosphonic acid concentrations were determined in leaves, roots, inflorescence rachi and flowers and in vitro pollen germination and pollen tube growth studied. Phosphonic acid concentration in the roots and floral parts was related to their sink strength at the respective times of application with concentration in roots highest (36.9.mg g±1) after treatment at summer flush maturity and in flowers (234.7 mg g±1) after treatment during early anthesis. Phosphonate at >0.03 M was found to be significantly phytotoxic to in vitro pollen germination and pollen tube growth. However, this rate gave a concentration far in excess of that measured in plant tissues following standard commercial applications of mono-dipotassium phosphonate fungicide. There was a small effect on pollen germination and pollen tube growth when 0.06 and 0.12 M mono-dipotassium phosphonate was applied during early anthesis. However, under favourable pollination and fruit set conditions it is not expected to have commercial impact on tree yield. However, there may be detrimental commercial implications from phosphonate sprays at early anthesis if unfavourable climatic conditions for pollination and fruit set subsequently occur. A commercial implication from this study is that phosphonic acid root concentrations can be elevated and maintained with strategic foliar applications of phosphonate fungicide timed to coincide with peaks in root sink strength. These occur at the end of the spring and summer flushes when shoot growth is relatively quiescent. Additional foliar applications may be advantageous in under high disease-pressure situations but where possible should be timed to minimize overlap with other signifcant growth events in the tree such as rapid inflorescence, and fruit development and major vegetative flushing.
 
Article
ISAFRUIT is an integrated European Union Project focussed on increasing fruit consumption as a means to improve human health, through evaluating the fruit chain and addressing bottlenecks therein.The innovations which are being developed throughout the ISAFRUIT Project have been analysed to determine both the success factors and the obstacles in reaching the commercialisation stage. Only 9.58% of the deliverables planned within the Project were focussed on developing technological innovations.There is evidence, however, of successes in the development of new innovations arising from the ISAFRUIT Project, with several other potential innovations in the pipeline. Of the technologies identified, 67% are still at the “invention stage”; that is, the stage prior to bridging the so-called “valley of death”, the stage between an invention and an innovation. Those which are considered to have moved over the “valley of death” either had industry partners included in the Project, or had consulted with industry to ensure that the technology was relevant, or met a recognised industry need. Many of the technologies which made less progress did not have the same interactions with industry. A number of other issues were identified which prevented further progress towards innovation. The need for scientists to publish scientific papers, both for their career pathways and to increase their chances of future funding, was identified as one issue, although the filing of patents is now becoming more accepted and recognised. The patenting system is considered complex by many scientists and is not well-understood. Finally, agreements between partners on the sharing of intellectual property rights can cause a delay in the innovation process.
 
Article
Graft incompatibility in solanaceous plants was investigated using representative cultivars of tomato (Solanum lycopersicum L.), eggplant (Solanum melongena L.), and pepper (Capsicum annuum L.). Evaluations of the extent of graft (in)compatibility were made by examining survival percentages, fruit yields, and fruit quality in grafted plants. Tomato/pepper (scion/rootstock) and pepper/tomato grafts were considered severely incompatible, and the tomato/eggplant and eggplant/tomato grafts were considered moderately incompatible, when compared with the compatible homo-specific graft combinations of tomato/tomato, eggplant/eggplant, and pepper/pepper. Three, or 3 and 6 weeks after grafting, the dry weights of scions and rootstocks, carbohydrate concentrations in stems above and below the graft unions, scion mineral nutrient concentrations, water potentials of scions, and xylem hydraulic conductivities were measured in the grafted plants. The anatomy of the graft unions was also observed. Growth inhibition and high mortality in tomato/pepper and pepper/tomato grafts (i.e., severe graft incompatibility) was due to discontinuities in the vascular bundles at the graft union, which prevented the translocation of assimilates, mineral nutrients, and water between scions and rootstocks. Reductions in fruit yield and/or fruit quality of tomato/eggplant and eggplant/tomato grafts (i.e., moderate graft incompatibility) may have been due to differences in the requirements for assimilates and mineral nutrients between tomato and eggplant. Plant responses to graft incompatibility varied in solanaceous plants depending on the scion and rootstock combination.
 
Article
Priming treatments (osmoconditioning), which can considerably improve seed germination performance, are widely applied by seed companies to increase the rate and uniformity of seedling establishment of commercial vegetable and flower seeds. Advancement of embryonic root tip cells into S and G2 phases of the cell cycle, as measured by the increase in the percentage of nuclei showing a 4C DNA content, has been observed to occur after osmoconditioning of pepper (Capsicum annuum L.) seeds. Here we report the relationship between osmoconditioning effects and the activation of DNA replication as well as the accumulation of β-tubulin, a constitutive element of microtubules, in the embryo root tips during priming in PEG 6000 solutions, at the osmotic potentials of -1.1 and -1.5 MPa. With dry seeds, flow cytometric profiles indicated that most of the cells were arrested at G1 phase of the cell cycle while β-tubulin was not detectable on western blots. During priming, β-tubulin appeared to be synthesized de novo and its accumulation preceded DNA replication. Within each priming condition, the time courses and amounts of DNA replication and β-tubulin accumulation were found to correlate with improved seed germination performance. Their potential use as molecular markers for discriminating a priori priming effectiveness is discussed.
 
Article
The effects of nitric oxide (NO) on lipid peroxidation and anti-oxidant activity in longan fruit were investigated during storage. Fruits were dipped for 5 min in a solution containing 1 mM sodium nitroprusside (SNP), an NO donor. They were then packed into polyethylene bags and stored for 6 d at 28 degrees C. Changes in pericarp browning index, membrane permeability, malondialdehyde (MDA) content, the rate of superoxide production, the activities of lipoxygenase (LOX), superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT), alpha,alpha-diphenyl-beta-picrylhydrazy (DPPH) radical scavenging activity, and reducing power were measured. Treatment with SNP inhibited pericarp browning and suppressed increases in membrane permeability and lipid peroxidation. These effects were associated with lower LOX activity, higher APX and CAT activities, better maintenance of DPPH radical scavenging activity and reducing power, and lower superoxide production rate. However, SOD activity was higher in control (non-SNP-treated) fruit than in SNP-treated fruit over the first 4 d of storage. Overall, these findings suggest that treatment with NO enhanced the anti-oxidant activity in pericarp tissue of longan fruit during storage, and contributed to reduced lipid peroxidation. Reduced lipid damage apparently maintained the compartmentation of enzymes and substrates and, thereby, lessened enzymatic browning.
 
Article
Maintenance of quality in fresh-cut produce is an important issue for the rapidly expanding minimal processing sector. Treatment of ethylene generating and/or sensitive fresh-cut produce with the ethyle ne-binding inhibitor 1-methylcyclopropene may assist in quality maintenance over time. Intact (control) and sliced 'Golden Delicious' apple fruit at 20degreesC were treated either with I-methylcyclopropene (1-MCP) for 6 h at 0.1 to 10 mul 1(-1) or 1 mul 1(-1) for periods of I to 6 h. Fruit was then kept at either 20degreesC or 4degreesC. Exposure of intact or fresh-cut apple fruit to 1-MCP resulted in reduced respiration and ethylene production rates and delayed softening and colour changes. The degree of benefit generally increased with increasing 1-MCP treatment concentration and duration. Compared with untreated tissue, quality was better maintained at 4degreesC for apple slices to which 1-MCP was applied either before or after the fruit were processed.
 
Time-course changes in the observed date of the F1 stage in 'Golden Delicious' apple trees recorded at three representative locations in the French cropping area. Each date is expressed in calendar days from 1 January of the flowering year (n).  
Article
This study aimed to improve the modelling of flowering time in fruit trees and to understand to what extent global warming has affected this trait since the end of the 1980s. The onset of flowering time (F1 stage) in apple trees has advanced by 7 - 8 d in France since the late 1980s. In this context, a sequential model composed of a chilling sub-model and a heat sub-model was considered. The input data consisted of F1 dates for 'Golden Delicious' apple in three French cropping areas from the North-West to South-East over the period 1976 - 2002 (81 F1 dates). A user-oriented software package, called 'Pollenoscope', automatically optimised combinations between seven chilling and three heat temperature functions. This was achieved by maximizing the R 2 values between the observed and simulated flowering dates. The study provided comparative information for assessing the respective effects of temperature functions commonly used for modelling flowering time in temperate trees. Three selected models explained 82 - 86% of the observed variability in flowering. Their fitness for an accurate prediction of the F1 date was validated using independent flowering datasets. All three models simulated similar time-course changes in the duration of the chilling effect at all three locations [i.e., a mean increase in the duration of this effect (by 3 - 5 d) since the end of the 1980s]. Consequently, it suggested that the duration of the heat effect had decreased (10 - 13 d) to explain the advance in flowering time. Hence, our results support the idea that global warming has, simultaneously, exerted two opposing effects in France between 1976 - 2002: (i) a slower mean rate of completion for the chilling requirement, and (ii) a higher mean rate of completion for the heat requirement. A more marked effect on completion of the heat requirement may have resulted from more pronounced warming from January to April, corresponding to the active growth phase of floral primordia, than from October to January, corresponding to the dormancy-breaking phase.
 
Article
Fresh apricots (Prunus armeniaca L.) are in high demand, but are available for only a short period during the Spring and the beginning of the Summer.There is no information on the correct harvest maturity stage that should be chosen to ensure a long post-harvest life and high sensory quality. The objective of this study was to evaluate the effect of maturity stage at harvest on the sensory quality of ‘Palsteyn’ apricots after 14, 28, or 42 d in cold storage. Sourness, flavour, and acceptability showed major changes during cold storage. Ripe fruit (orange-yellow skin colour) showed the highest acceptability, as assessed by a “mini-consumer test” (i.e., an untrained panel; n = 36). Fruit harvested at an intermediate stage of maturity (light yellow skin colour) reached an average acceptability, while unripe fruit (greenish skin colour) were not acceptable. After 28 d of cold storage, fruits were still acceptable; but, after 42 d, fruits reached the “dislike” zone. On a principal component analysis, acceptability was shown to be positively associated with sweetness, flavour, juiciness, and aroma, and negatively associated with sourness. After 28 d and 42 d of cold storage, unripe fruit appeared to have low acceptability and quality attributes. ‘Palsteyn’ apricot harvested with an orangeyellow skin colour, as the least ripe fruits, showed that they could reach high sensory quality standards and were able to withstand long periods of cold storage.
 
Article
The effects of post-harvest dips with calcium salts on the quality attributes of nectarine fruits (Prunus persica var. nectarina Ait. Maxim, cv. ‘Caldesi 2000’) were determined after harvest or in cold storage for up to 6 weeks. Nectarine fruits were harvested at the firm-ripe stage (flesh firmness 70 ± 2 N; soluble solids content 10.5 ± 0.2%) and dipped in deionised water (control) or calcium salts (chloride, lactate or propionate) at two calcium concentrations (62.5 or 187.5 mM). The calcium content of nectarine fruits increased up to 240% in the peel, and up to 31% in the flesh, 1 d after immersion. The increase in calcium content in the flesh was accompanied by increased cell wall calcium, corresponding to a significant increase in the “insoluble” pectin fraction. The highest calcium accumulation in the “insoluble” pectin fraction was attained with 62.5 mM calcium which positively affected fruit firmness. The higher calcium concentration (187.5 mM) resulted in increased calcium in the “water-soluble” pectin fraction which did not appear to contribute to retention of tissue firmness. Additionally, still higher concentrations of calcium lactate and calcium propionate resulted in surface damage, leading to undesirable characteristics during fruit ripening.
 
Article
The influence of assimilate supply on leaf formation in sweet pepper and tomato was investigated. Assimilate supply for vegetative growth was varied by light intensity, by plant density and by fruit, truss and leaf pruning. In both species, a higher assimilate supply led to an increasing dry weight of the vegetative parts of up to 82%, whereas leaf appearance rate was hardly affected. Area of individual leaves was hardly influenced by fruit or leaf pruning, but increased with increasing light intensity, decreasing plant density or the removal of every other truss. Increased assimilate supply resulted in an increase in dry weight of individual leaves and a decrease in specific leaf area. In addition, for sweet pepper grown under daylight conditions at a constant 24-hour temperature, the rate of dry weight increase of total plant and vegetative parts changed considerably (coefficient of variation (CV) 0.52 and 0.44, respectively), but leaf appearance rate was rather constant during a growing season (CV = 0.07). It is concluded that, within a large range, assimilate supply had little effect on leaf appearance rate during the generative stage of sweet pepper and tomato plants, whereas leaf size was affected.
 
Article
The influence of assimilate availability on the number of flowers per plant, individual flower size and plant height of chrysanthemum was investigated in different seasons, integrating the results from eight greenhouse experiments. Increased assimilate availability was obtained by higher light intensity, higher CO2 concentration, lower plant density or longer duration of the long-day (LD) period. Within each experiment, conditions that were expected to increase assimilate availability indeed resulted in higher total dry mass of the plant, excluding roots (TDMp). In contrast, flower mass ratio was hardly affected, except for the increased duration of the LD period that significantly reduced the partitioning towards the flowers. Consequently, an increase in total flower dry mass with assimilate availability was observed and this was mainly a result of higher numbers of flowers per plant, including flower buds (NoF). Individual flower size was only influenced by assimilate availability when average daily incident PAR during short-day period was lower than 7.5 mol m-2 d-1, resulting in lighter and smaller flowers. Excluding the positive linear effect of the duration of the LD period, assimilate availability hardly influenced plant height (<10% increase). It is concluded that within a wide range of growth conditions chrysanthemum invests additional assimilates, diverted to the generative organs, in increasing NoF rather than in increasing flower size. Irrespective of the growth conditions and season a positive linear relationship (r22 = 0.90) between NoF and TDMp was observed. This relationship was cultivar-specific. The generic nature of the results is discussed.
 
Article
The effects of modified atmosphere (MA) conditions on the quality of minimally processed pineapple slices were determined. Commercial pineapple slice packs sealed with 40 pm thick polyester film were kept at 4.5 degrees C for 14 d. The oxygen transmission rate of the film was 23 ml m(-2) day(-1) atm(-1) (at 25 degrees C, 75% RH). In-built atmospheres and the quality of the products were determined. O-2 concentrations within the packs stabilised at 2%, while CO2 concentrations increased to 70% by day 14. The high CO2 level suggested an inappropriate lidding film permeability for the product, and hence affected its quality. Three batches of pineapple slices were packed in the laboratory using lidding films with oxygen transmission rate of 75, 2790 or 5000 ml m(-2) day(-1) atm(-1) (at 23 degrees C, 0% RH). Headspace atmospheres from laboratory-packed pineapple slices suggested an optimum equilibrium modified atmosphere of ca. 2% O-2 and 15% CO2. Respiration data from the laboratory-prepared packs were pooled together and used to develop a correlation model relating respiration rates to O-2 and CO2 concentrations. The model showed a decrease in respiration rate with decreasing O-2 and increasing CO2 concentrations. Respiration rate stabilised at 2% 02 and 10% CO2. The high concentrations of CO2 observed in the commercial packs did not fit the range in the respiration model. The model could aid in selection of MA conditions for minimally processed pineapple fruit.
 
Article
Peeling and cutting processes wound tissues and enhance deterioration in minimally processed fruits. Controlled atmosphere (CA) or modified atmosphere (MA) conditions can help maintain the quality of minimally processed products. The effects of various combinations Of CO2 and O-2 on the quality of fresh pineapple (cv. Smooth Cayenne) slices held at 4.5 degrees C were investigated. Among a range of CA treatments, 15 kPa CO2 maintained flesh colour, with low alcohol and acetaldehyde concentrations, and also prevented microbial growth. O-2 at 5 kPa also maintained a high visual quality, and gave low alcohol and acetaldehyde concentrations. Likewise, O-2 at 80 kPa maintained a high visual quality and prevented the accumulation of fermentation-related volatiles, but caused high electrolyte leakage. Both 5 kPa and 80 kPa O-2 treatments resulted in a reduced loss of firmness. Nonetheless, the respiration rate was higher in 80 kPa O-2 than in 5 kPa O-2. When the Optimum O-2 and CO2 concentrations were combined and compared to 21 kPa O-2 + 0 kPa CO2 (air control), both 5 kPa and 80 kPa O-2, with 15 kPa CO2, maintained the quality of pineapple slices. However, because low O-2 is more readily attained and maintained in MA, 5 kPa O-2 + 15 kPa CO2 appeared to be the most appropriate atmosphere for storage of minimally processed pineapple fruit.
 
Article
Near-ripe ‘Kensington Pride’ mango (Mangifera indica L.) fruit with green skin colour generally return lower wholesale and retail prices. Pre-harvest management, especially nitrogen (N) nutrition, appears to be a major causal factor. To obtain an understanding of the extent of the problem in the Burdekin district (dry tropics; the major production area in Australia), green mature ‘Kensington Pride’ mango fruit were harvested from ten orchards and ripened at 20 ± 0.5 O C. Of these orchards, 70% produced fruit with more than 25% of the skin surface area green when ripe. The following year, the effect of N application on skin colour and other quality attributes was investigated on three orchards, one with a high green (HG) skin problem and two with a low green (LG) skin problem. N was applied at pre-flowering and at panicle emergence at the rate of 0,75,150,300 g per tree (soil applied) or 50 g per tree as foliar N for the HG orchard, and 0,150,300,450 g per tree (soil applied) or 50 g per tree (foliar) for the LG orchards. In all orchards the proportion of green colour on the ripe fruit was significantly (P<0.05) higher with soil applications of 150 g N or more per tree. Foliar sprays resulted in a higher proportion of green colour than the highest soil treatment in the HG orchard, but not in the LG orchards. Anthracnose disease severity was significantly (P<0.05) higher with 300 g of N per tree or foliar treatment in the HG orchard, compared with no additional N. Thus, N can reduce mango fruit quality by increasing green colour and anthracnose disease in ripe fruit.
 
Article
To determine the potential for rootstocks to improve avocado quality, 'Hass' fruit from trees on seedling 'Velvick' (SV), clonal 'Velvick' (CV) or clonal 'Duke 7' (CD) rootstocks were harvested in 1999 and 2000, ripened at 20 C immediately after harvest (non-stored) or stored at 5 C for four weeks (stored), and then fruit quality and mineral concentrations determined. In 2000, non-stored CV fruit had lower severity of body rots (5% of flesh volume affected, caused mainly by Colletotrichum gloeosporioides) than CD fruit (20%), while body rots severity in stored CV fruit was 20% compared with 38% in stored CD fruit. Stored CV fruit had less severe diffuse discoloration (3% and 9% in 1999 and 2000, respectively) than CD fruit (7% and 20%, respectively). Stored CV fruit also had less severe vascular browning (19%) than CD fruit (33%) in 2000. In both seasons, CV fruit had 15-19% higher flesh calcium concentrations, 17-22% higher flesh boron concentrations, and 14-15% lower flesh nitrogen concentrations than CD fruit. In 2000, CV fruit also had 27% more skin calcium and 14% less skin nitrogen than CD fruit. There were no effects of rootstock on yield, canopy volume, measured length of non-suberized roots, average fruit weight, fruit length: width ratio, skin thickness, dry matter, proportion of the fruit skin purple-black when ripe, or seed mass: fruit weight ratio. These results suggest that there is potential to improve 'Hass' avocado quality through rootstock selection, and that tree and fruit mineral concentrations have a role in this relationship.
 
Article
The effects of nitric oxide (NO) treatment on the sensitivity of banana fruit slices to ethylene were investigated. Fruit slices were partial-pressure infiltrated for 3 min in a NO donor solution of 5 mM sodium nitroprusside (SNP), followed by treatment with 100 μl I-1 ethylene for 24 h, then packed into polyethylene bags and stored for 5 d at 24°C. Control slices were treated with distilled water instead of SNP, then treated with ethylene. Changes in fruit firmness, chlorophyll content, respiration rate, the activities of three cell wall modifying enzymes [polygalacturonase (PG), endo-β-1,4-glucanase (EGase), and β-galactosidase (β-Gal)], and total amylase activity were measured. Expression of the expansin (MaExp1) and ethylene receptor (MaERS2) genes were also analysed. The application of NO, prior to ethylene exposure, retarded pulp softening and peel de-greening. Pre-treatment with NO also decreased the respiration rate of banana fruit slices during ripening. Delayed pulp softening by NO was associated with decreased activities of PG, EGase, β-Gal, and total amylase, as well as reduced expression of the MaExp1 gene. Expression of the MaERS2 gene was also suppressed in NO-treated banana fruit slices. Collectively, these findings suggest that NO pre-treatment decreased the sensitivity of banana fruit slices to ethylene, and thereby delayed ripening.
 
Article
This case study reports the post-harvest qualities of conventionally versus organically grown banana fruit from nearby plantations in the Dominican Republic. The comparison involved six repeated harvests over the transition from cooler to hotter seasons. Green mature Cavendish 'Grande Naine' banana fruit were shipped to the UK. They were triggered to ripen with ethylene gas and kept under simulated retail conditions. Fruit mass, colour, firmness and flavour parameters were measured every second day over 12 d of shelf life. Sensory comparisons were conducted on four of the six harvest times. Significant differences (P<0.05) in measured quality attributes between conventionally and organically grown fruit were few and marginal. Moreover, any differences were inconsistent across harvest-times and during shelf life. Thus, organically and conventionally grown product had almost identical qualities. Sensory comparison confirmed that there was no flavour difference. This case study provides data that challenge a general perception that organic bananas have better flavour than conventional bananas.
 
Article
The importance of new basal-shoot formation for plant development and flower production of Rosa hybrida 'Motrea' was studied for more than four years. After one year, new basal-shoot formation was either restricted or undisturbed. In both treatments, fresh-weight production decreased after the second year; this is discussed in relation to an increase in respiration as a result of an increase in stem biomass. Limiting the number of new basal shoots increased flower weight and slightly enhanced flower production during the second year as compared with leaving all renewal canes on the plant. In the latter case, the number of basal stems was almost twice as high after three years. New basal shoots may compete with existing ones as indicated by the limited diameter increase and the higher mortality rate for old basal shoots in comparison with the treatment in which basal-shoot formation was restricted. Further, the weight of flowers harvested from new basal shoots was clearly greater than from older shoots. However, restricted basal-shoot growth had hardly any significant effects on the total number of harvested flowers and average flower weight as compared with the undisturbed situation. In the fourth year a slightly decreased flower production was observed in the case of restricted basal-shoot formation. It may be concluded that there is no relation between the number of basal shoots and flower production over a series of years.
 
Article
The objective of this research was to study the role of fruit expansion and turgor in the formation of cuticular cracking in bell pepper (Capsicum annuum L.). Fruit was artificially cracked by filling detached hollowed pepper fruits with distilled water. However, when isotonic mannitol solution was used, cracking did not occur. Similarly, immersion of intact red fruits in tap water caused formation of cuticular cracks following a delay of 30 h during which the turgor potential of the red pericarp and the expansion of the fruit diameter increased to critical threshold values of 0.65 MPa and 1-2%, respectively. On the other hand, in the greenhouse, attached red fruits underwent diameter change of only 0.2% and, when most expanded, the fruit had a turgor potential of only 0.3 MPa. In greenhouse grown plants, pepper fruits become susceptible to cracking at the stage of colour turning, a stage at which they also become susceptible to artificially induced cracking by immersion in water. Under greenhouse conditions both young and mature fruits exhibited growth independent of diurnal diameter fluctuations. Larger diameter fluctuations were observed in mature fruit, under conditions which encouraged cracking. Based on these results, we suggest that it is the magnitude of the diurnal fluctuations in fruit turgor and diameter, continuing over a long period which may cause the splitting of the cuticle.
 
Average stigma receptivity (shaded bars, n=70) and pollen viability (white bars, n=100) +SE during flower life.
Article
In this paper, the floral biology and pollination ecology of Salvia splendens are described. All flower characteristics (red corolla, large tubular flowers with abundant but dilute nectar) indicate that S. splendens is adapted to hummingbird pollination. Honeybees, however, were also found to be good pollinators of this plant. Apis mellifera was equally effective in pollinating S. splendens as hand pollination and open pollination, resulting in a 300% increase in seed set compared with bagged control plants. The much smaller stingless bee Tetragonisca angustula was not an effective pollinator of these flowers since during visitation its body failed to touch the stigma. Although pollination seemed not to be the only limiting factor in seed production, external pollinators enhance seed production in S. splendens, and Apis mellifera is an effective, commercially available pollination agent of this economically important ornamental plant.
 
Top-cited authors
Zora Singh
  • Edith Cowan University
Raphael Abraham Stern
  • Migal - Galilee Technology Center
Anita Sønsteby
  • Norwegian Institute of Bioeconomy Research
Ola M. Heide
  • Norwegian University of Life Sciences (NMBU)
J. A. Franco
  • Universidad Politécnica de Cartagena