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Mango fruit is a tropical crop characterized by heterogeneity in fruit size and quality at harvest. The effect of source-sink relationships on fruit production have been reported in many species but their interplay at the branch, scaffold and tree scales has been little investigated. This study aims at evaluating how source-sink relationships from a local (branch) to a global (tree) scale affect fruit production. Experiments were conducted on mango trees ('Cogshall') in Réunion Island. Fruit-bearing branches were randomly selected on six trees with low to high fruit load. Half of them were girdled and ratios of 10 and 100 leaves fruit‑1 were established on girdled and non-girdled branches. Pulp dry matter content, titratable acidity and total soluble solids were measured on one ripe fruit per branch. Number of fruits, yield and trunk and scaffolds cross-sectional areas were collected on these trees, and on other trees over several years. Average fruit fresh mass at the scaffold and at the tree scales was negatively related to fruit load, expressed in number of fruits per scaffold and per trunk cross-sectional area, respectively. A global negative effect of tree fruit load on average fruit fresh mass at the scaffold scale was also observed. Between-trees variability of average fruit fresh mass decreased with fruit load. At the branch scale, low leaf-to-fruit ratio and girdling induced fruit drop in the early stages of fruit development and reduced fruit growth, pulp dry matter content and total soluble solids. Results suggested partial autonomy of the scaffolds and fruit-bearing branches with respect to fruit growth. As a next step, a modeling approach integrating carbon-related processes from the branch to the tree scale should be used to further investigate to what extent source-sink relationships, and other factors such as light environment or water availability, can explain fruit production variability.

Girdling, otherwise known as cincturing or ring barking, was tested for its ability to improve yield and quality of Actinidia chinensis var. deliciosa ‘Hayward’, A. chinensis var. chinensis ‘Hort16A’ and, more recently, A. chinensis var. chinensis ‘Zesy002’ kiwifruit grown commercially in New Zealand. Originally, we developed girdling of individual 1-year-old fruiting canes as a technique to increase fruit size for organic kiwifruit growers. However, the technique was rapidly adopted by growers of conventional kiwifruit. Girdles healed rapidly within 3-6 weeks of application, and plants recovered fully. Cane girdling was largely superseded by girdling of the main trunks, which resulted in similar benefits to cane girdling, but was faster to apply, responses were larger, and there was less variability of fruit characteristics within vines. However, there was some risk of negative plant responses if girdles were applied too deeply, so that the xylem tissue was damaged, or when girdles were applied late in the growing season. In both of these cases, girdles did not always heal before winter, and development of leaf canopies in spring was retarded. Timing of girdle applications was critical for response. Girdles applied soon after fruit set, during the rapid phase of fruit growth, increased fruit weight, while those applied during the starch accumulation phase increased dry-matter content of fruit and improved the eating quality of fruit. Girdles applied in autumn increased bud break and flower numbers of vines in the following season. The story of how girdling was developed for New Zealand kiwifruit growers is also an informative case study. It demonstrates that a significant extension plan is required for the rapid adoption of even a relatively simple new technology by a horticultural industry.

Taiwan's scientists have bred and released a number of fruit cultivars last decade, including papaya, Indian jujube, pineapple, wax apple, guava, mango, lychee, sugar apple pitaya and carambola. These new cultivars provide a richer choice of healthy products and better fruit quality that enrich the food supply for Taiwanese. The most preferred characteristics for varietal development of fruit are targeted at enjoyable flavor, comfortable total soluble solids (TSS), thick flesh, disease resistance, longer shelf life, and vigor growth. For some of them, color of flesh or skin, high yielding potential, and rich nutrient are also important. Recently, high resistance (tolerance) to pests and diseases are emphasized in research. Solutions to the problem have been found and used with good result in the farmer orchards. Then, cultivation techniques were advanced for unseasonal fruit production of wax apple, guava and sugar apple. The fruits can be produced in their season and off-season, a year-round production. The forcing culture technique was used for short breeding program at least 2-3 years, for example covering with black nylon net, girdling, flooding, root cutting, grafting and fertilizers techniques. We are continuously releasing new cultivars of fruits and transferring technologies to bring the efforts of the R&D program for outputs into outcomes practice in Taiwan.

The fruit production in the tropics offers a greater scope to modify a plant's flowering and fruiting cycles than in temperate areas. Changing the normal seasonal flowering cycle offers growers considerable economic advantages, by enhancing the ability to market tropical fruit in the off-season. A grower can cycle different blocks of trees to provide continuous employment for workers, schedule production to avoid the peak periods when gluts occur and often the price is less than the production costs, and can accept orders to deliver fruit at a future date. The practices used to modify the timing of flowering also offers the opportunity to improve product quality and reduced cull losses when coupled with practices such as fruit thinning and bagging. Cold temperatures and photoperiodism determine flower induction in temperate, and subtropical growing areas. The cold season in the subtropics often leads mango, for example, to have only one flowering cycle per year, whereas in the tropics, it might flower two to three times per year. The phenology of many tropical fruit crops and some temperate crops when grown in the tropics can be modified by production practices such as the fertilization and irrigation, pruning and chemical treatments. However, differences occur in the varietal responses to these modified practices. The classic example of a change in the seasonal timing of flowering is pineapple, after it was observed that smoke induced off-season flowering in this photoperiodic species. Water stress and fertilization timing frequently play a significant role in modifying seasonal flowering patterns in tropical species, as does girdling, shading, roots pruning and chemical treatments to stimulate and inhibit growth. Plant growth regulators and inhibitors are used to hasten the completion of the natural phenological vegetative and root growth phases and prepare the tree for flowering. The modification of the natural phenological cycles has raised concerns by some orchardists and researchers that the tree's useful life might be reduced. The reduction in a tree's productive life due to cycling can incur additional expenses to replant and wait for the new planting to mature and produce fruit. It would be necessary to balance the cost of replanting, if needed, with the advantages from cycling trees to achieve higher fruit prices. Examples of crops where flowering and fruiting cycles have been modified, include; carambola, durian, grape, guava, longan, mango, pineapple, rambutan, sweetsop and wax apple. The potential also exists to tailor production practices in other tropical fruit crops to allow year-round marketing of high quality tropical fruit.

The most important problem in world citrus production is the bacterial disease Huanglongbing (HLB; greening) which is caused by a phloem-limited bacterium that is vectored by a phloem-feeding psyllid. The earliest visible symptoms of HLB in leaves are an asymmetrical chlorosis referred to as "blotchy mottle", thought to be from starch accumulation from a phloem dysfunction and a decline in root health. We tested the hypothesis that such visible symptoms are not unique to HLB by stemgirdling two year-old seedling trees of 'Cleopatra' mandarin and 'Swingle' citrumelo rootstocks in the greenhouse. Girdling induced a 4-fold greater starch concentration in leaves on well-watered trees while starch in woody roots of girdled trees decreased up to 19 fold relative to non-girdled trees. Drought stress cycles induced some starch accumulation in non-girdled roots but there were no effects of drought stress on root starch in girdled trees. Girdling reduced leaf transpiration in well-watered trees. Leaves on girdled trees clearly had HLB-like visible blotchy mottle symptoms but no visible symptoms developed on non-girdled trees. The up to 40% increase in leaf starch increased leaf dr wt per leaf area (DW/LA) and consequently reduced many leaf nutrients on a leaf DW basis. Most of these differences disappeared when expressed on a LA basis except for the girdle-induced decreases of leaf phosphorous and sulphur. Leaf boron (B) was inversely related to leaf starch when both were expressed on a LA basis. In the absence of HLB, girdling increased leaf starch, decreased root starch, and duplicated the asymmetric blotchy mottled visual leaf symptoms that have been associated with HLB-infected trees.

Major export countries use a matrix of quality attributes of fruit at harvest to support decisions on the travel potential of key cultivars. However there is uncertainty whether levels of firmness and soluble sugars at harvest are indicative of these attributes postharvest. The objective of this study was to determine the effects of manipulating tree carbohydrate availability through girdling or defoliation on fruit quality at harvest and postharvest. Trunk girdling and limb defoliation treatments were applied five weeks after full-bloom in trees of 'Kordia' and 'Lapins' cultivars in order to manipulate carbohydrate supplies to fruit. Fruit were harvested at commercial maturity and analysed for fruit quality and chemistry parameters at harvest and after 28 days of postharvest storage. Girdling in 'Kordia' resulted in fruit that were significantly firmer, higher in TSS, and larger in diameter which was further pronounced after postharvest storage. Defoliation in 'Kordia' resulted in fruit that were softer, had lower TSS, and were smaller in both mass and diameter. The 'Lapins' treatments often didn't respond in the same way that 'Kordia' did and thus the results of this study indicate a distinct carbohydrate source: sink relationship in 'Kordia' relative to 'Lapins', which may be due to differences in sink competition. Therefore this study indicates that girdling can lead to increased carbohydrate availability resulting in higher quality fruit, particularly following postharvest storage which could improve outcomes when exporting.

Fruitlet abscission is an issue impacting the profitability of the cherry industry, with particular cultivars showing enhanced susceptibility. This study examined the role of carbohydrate availability in fruitlet abscission in two sweet cherry cultivars, 'Kordia' and 'Lapins'. Starch and soluble sugar concentrations in branch, trunk and root tissue were measured regularly throughout the growing season of 2012/2013. Normal transport of carbohydrates was disrupted 5 weeks after full-bloom by applying trunk girdling and limb defoliation treatments, and the rate of flower and fruitlet abscission was monitored. In 'Lapins', trunk girdling decreased the rate of abscission, but abscission was unaffected by girdling in 'Kordia'. When fruit was assessed at commercial harvest, the fruit from the defoliated treatment was immature in both cultivars. The highest sugar concentration was found in fruit from the girdled trees in both 'Kordia' and 'Lapins'. Trunk starch concentrations ranged from 22.6 mg g-1 at the beginning of the season to 28.80 mg g-1 just after harvest in 'Lapins', and were higher in 'Kordia' with 42.02 mg g-1 at the beginning of the season to 39.13 mg g-1 just after harvest. Shoot starch concentrations were very similar to trunk in both cultivars, whereas root carbohydrate concentrations did not recover after the trunk girdling treatment in either cultivar, which is expected to have an impact on the following season's return bloom.

The effect of carbohydrate sources on vegetative growth in macadamia at two major flushing times (March and September in southern hemisphere) were studied indirectly by measuring the growth rate of individual flushes in response to girdling and defoliation treatments during the vegetative growth period. Internode length and girth of a single flush were affected significantly by girdling and defoliation treatments. Two sources of carbohydrate were hypothesised for vegetative growth of the single flush; reserved carbohydrate and current photosynthate. The contribution of these sources to vegetative growth were defined and calculated from the differences between the combinations of girdling and defoliation treatments over time. Based on the results for two major flushing times, reserved carbohydrate contributes more to vegetative growth of macadamia than current photosynthesis.

The quality of wine is influenced primarily by the quality of the raw material and secondly by fermentation technology. In general, important methods of cultivation for increasing the quality of the grape are shoot thinning, desuckering, shoot positioning and topping, basal leaf removal, girdling, cluster thinning and berry thinning. In this study the influence of cluster thinning was investigated to set standards for management for the grape cultivar ?Doonuri?. The ?Doonuri? grape was a cross of ?Schuyler? and ?Campbell Early? at the National Institute of Horticultural and Herbal Science in Korea in 2006. This red grape has a full fruit aroma, and it was used as a table and wine grape. In addition, this cultivar had a resistance to cold in winter as well as a downy mildew resistance. The fruit setting of grapes after cluster thinning was adjusted to 1.1 ton (1 cluster per shoot), 1.5 tons (1.5 clusters per shoot), and 2.1 tons (2 clusters per shoot) per 10 ares. As a result, ripening was faster when the yield was 1.5 t then 2.1 t per 10 are. Total acidity was reduced about 0.2% (w/v) at 1.5 t compared with 2.1 t. On the other hand, the sugar content was higher, about 2~3°Brix. The total acidity and sugar content for the 1.1 and 1.5 t levels were not significantly different. As cluster thinning increased, total polyphenol and total anthocyanin contents increased with early maturity. Also, the grapes with less 1.5 t per 10 acre were able to produce high quality wine.

A causal agent for Dry root rot (DRR) of citrus has not been definitively identified, but the organism most consistently associated with DRR is Fusarium solani (Mart.) Sacc. To efficiently screen a citrus germplasm collection for resistance to F. solani, a core subset of the collection was evaluated. Seedlings of forty-five accessions were wounded by girdling. Treatment consisted of inoculation with F. solani, with uninoculated controls. Three parameters were evaluated: recovery from girdling (0 - 3); amount of DRR (0 - 4); and percentage of healthy feeder roots. Twenty-four accessions showed no significant difference in DRR between inoculated and uninoculated seedlings, and 12 of these accessions showed low development of DRR ( 2.7). Twenty-four accessions showed no significant difference in % healthy feeder roots between inoculated and uninoculated seedlings and eight of these showed a high percentage (> 80 %) of healthy feeder roots. Five accessions were superior in all three parameters: 'Fremont' mandarin (PI 539507), 'Lamas' lemon (PI 539226), 'Mato buntan' pummelo (PI 529398), 'Olivelands' sour orange (PI 539164), and 'South Coast Field Station' citron (PI 539435). These accessions would probably represent the best candidates for further study of F. solani resistance.

The objective of this study was to investigate the basis for yield differences between ‘Kordia’ and ‘Sylvia’, low- and high-crop load carrying sweet cherry cultivars, respectively. Branch girdling was effected on ‘Kordia’ and ‘Sylvia’ set up as Spanish Bush at Old Beach in the Derwent Valley, near Hobart, Tasmania, Australia. Photosynthesis was measured with a Li-Cor 6400 four times pre- and once post-harvest. Fruit set was 42% and 56% and fruitlet abscission was 69% and 34% in ‘Kordia’ and ‘Sylvia’, respectively. Maximum photosynthetic rate ( A sat ) increased from a low or around 12 µmol m -2 s -1 in early Spring to a maximum of around 18 µmol m -2 s -1 early Summer and was similar between cultivars pre-harvest. However, post-harvest, A sat of ‘Kordia’ was significantly lower at around 8 µmol m -2 s -1 relative to that of ‘Sylvia’ at around 16 µmol m -2 s -1 . Girdling had a stronger effect on A sat in the low-yielding ‘Kordia’ than in the high-yielding ‘Sylvia’ (-13% vs. -11%, respectively), and there was a greater increase in foliar soluble sugar (SS) content in ‘Kordia’ than ‘Sylvia’ (+18% vs. +13%), averaged across the season. There was a strong negative correlation between SS and A sat in leaves, across the season, cultivars and treatments. There were no girdling or cultivar effects on foliar starch content. The results suggest that girdling-induced sink-limitation leads to down-regulation of photosynthesis that is linked to the accumulation of SS content in the leaves. Despite minor differences in A sat between varieties, our results imply that the low-yielding ‘Kordia’ variety is not limited by source-supply potential during the growing season, but that low A sat post-harvest could be linked to the subsequent season’s fruitlet abscission that limits potential yields. Further investigation is warranted regarding carbohydrate storage as a factor in the relatively high fruitlet abscission in ‘Kordia’, and other low-yielding varieties of sweet cherry.

Girdling can be used as a valuable research tool to improve our understanding of the tight coupling between water (xylem) and sugar (phloem) transport. Therefore, double girdling was applied on young oak trees (Quercus robur L.) to manipulate the sugar flow by mechanically removing a complete band of bark at two different heights. The double girdling effects on both the water and sugar transport were investigated by analysing stem diameter variations, photosynthesis, xylem sap flow and content of carbohydrates. The double-girdled oak trees were divided in three stem zones: (1) the upper stem zone (U) still receiving new assimilates from the leaves, (2) the lowest stem zone (L) receiving only stored sugars from the roots, and (3) the middle stem zone (M) completely isolated from crown and roots. As downward carbon transport was interrupted by girdling, the stem expansion and carbohydrate content increased in U, indicating that U became the major sink instead of the roots. In contrast to U, stem expansion and carbohydrate content decreased in the two lower stem zones (M and L). Furthermore, a decrease in photosynthesis and sap flow rate was observed, which could be attributed to an indirect effect of girdling.

Trunk spiral girdling was carried out on six years old litchi (Litchi chinensis Sonn. 'Nuomici' and 'Guiwei') trees which poorly fruiting during the early flower bud differentiation phase (about early December). A 1.2 to 1.8 spiral circle with a width of 0.2 to 0.4 cm and a spiral angel of 16-19 degrees was extended into the xylem of the trunk or branch. The wound was almost healed at harvesting time. Compared with the control (no girdling), the ratio of fruit-setting plants was 55.3, 64, 74.7, 78, 74 and 73.3% higher in cultivar 'Nuomici', and 58, 62.7, 68.7, 73.3, 70 and 65.4% higher in cultivar ‘Guiwei’ in 2000, 2001, 2002, 2003, 2004 and 2005, respectively. Yield per plant was 2.5, 4.2, 6.5, 9.2, 13.5 and 16.5 kg higher in cultivar 'Nuomici', and 2.4, 3.8, 5.5, 8.9, 13.9 and 14.8 kg higher in cultivar ‘Guiwei’, respectively. The plants with spiral girdling fruited 6 years early than control. Total sugar concentration in fruit of plant with spiral girdling was 3.5 and 2.1% higher than those in control, while total acid concentration was 0.7 and 0.4% lower than those in control in cultivars ‘Nuomici’ and ‘Guiwei’, respectively.

The effects of different source-sink ratios on fruit quality were studied for the table olive cultivar ‘Picholine’. This cultivar represents 15% of the production of table olives in Tunisia. Fruit size is an important quality parameter for table olives as small fruits have lower economical value. Three tertiary branches/tree were selected on 27-years-old olive trees (10 trees in total) at the start of the growing season 2009. After fruit set in early May four fruit-to-leaf ratios were imposed on 1-year-old wood (no fruits, 1:1, 1:2, 1:3) of each branch. Apexes of all shoots were removed in order to reduce the vegetative sinks. In mid-July five trees were randomly selected and all branches were girdled. The absence of fruits or girdling decreased leaf net photosynthetic rate (An) and increased leaf carbohydrate contents. Girdling stimulated fruit growth, while the effect of leaf-to-fruit ratio was less pronounced.

Kiwifruit production systems in New Zealand are driven by the need to achieve both high productivity (yield of Class 1 fruit per canopy hectare) and superior fruit taste for consumers. Fruit dry matter content at harvest (DMC) is used as a proxy for potential taste of ripe fruit, and growers receive incentives to produce high DMC fruit. High DMC fruit would be considered c. 17% for 'Hayward' and c. 18.5% for 'Hort16A', with starch accounting for most of the DMC at commercial harvest. Vine management systems need to optimise both fruit number and fruit size per unit area of canopy as well as maximising the partitioning of carbohydrate to the fruit, to achieve this high starch content. In New Zealand, a number of plant management techniques have been introduced to manage fresh and dry matter accumulation in fruit over the last 10 years. This has occurred by an active process of intensive research, development and technology transfer extension. Techniques successfully introduced include girdling, management of fruit biostimulants, gel pruning, cane stringing and thinning. By integrating these techniques with existing orchard management procedures and ongoing fine tuning of on-orchard systems, top performing growers can consistently deliver both high productivity and high taste potential. In this paper, we outline several of these management techniques.

Pomegranate (Punica granatum L.) regarded as a “Fruit of Paradise” is one among the major fruit crops of arid zones. The crop is mainly grown in Maharashtra, Karnataka, Andhra Pradesh and Tamil Nadu. In Karnataka, it is extensively cultivated in the northern districts viz., Bijapur, Bagalkot, Bellary and Koppal. It was a dollar earning and boom commercial fruit crop for farmers since 2002. From the year 2002, growers are in dire straits due to severe outbreak of bacterial blight caused by Xanthomonas axonopodis pv. punicae, which was once deemed as a minor important disease and became a serious threat for pomegranate production resulting in severe yield losses both in terms of quality and quantity. A survey report revealed 20-90% of disease severity in Bijapur and Bagalkot district. Similarly 71.14% severity was reported in Bellary district. Recent reports revealed the highest severity of trees was 74.80% in Bagalkot district and minimum severity (6.73%) in Bellary district. The disease is characterized by the appearance of one to several small water soaked, dark colored irregular spots on leaves resulting in premature defoliation under severe cases. The pathogen also infects stem and branches causing girdling and cracking symptoms. Spots on fruits were dark brown irregular slightly raised with oily appearance, which split open with L-shaped cracks under severe cases. Screening of different botanicals and bactericides by in vitro method revealed the superior efficacy of bactrinashak at 0.05% (20 mm inhibition zone) followed by streptocycline (0.05%). Garlic extract 5% was found the next best effective treatment. Field evaluation over the seasons showed that bactrinashak, streptocycline or bacteri¬mycin at 0.05% concentration in combination with COC 0.25% were equally effective in reducing the disease severity. Integrated disease management practices like selection of disease free seedlings, use of organics, proper spacing, pruning time, method of pruning, sanitation, sufficient rest after harvest and use of antibiotics with copper fungicides have proven well in reducing the severity of bacterial blight of pomegranate. Since it is an airborne disease, a mass eradication program will be beneficial.

The low fruiting is one of the main problems related to the pear production in Brazil. In this context, this work aimed to determine the fruit set of pear fruits 'Garber' in the different fruiting organs regarding the North, South, West and East quadrant by using physical and chemical treatments. Sixteen-year-old trees were conducted at spacing of 6 × 8 m. The treatments were: 1) control; 2) summer short pruning; 3) branches bending + summer long pruning; 4) winter branches bending; 5) winter pruning; 6) girdling; 7) 560 ml 100 L -1 of H 2 0 of Promalina ® (benzyladenine + gibberellins AG 4 +AG 7 ) or 8) 200 ml 100 L -1 of H 2 0 of Biozyme*TF. After 55 days, the fruits fixed in the different fruiting organs as lamburde, brindille, brindille couronnee and bourse were counted. The girdling treatment done in the winter time showed the highest effective fruit set rates independent of fruiting organs. The use of Promalina ® and winter bending were not efficient to the pear tree 'Garber' in this experiment conditions. The effective fruit set was similar at all the orientation quadrants in the region of Pelotas-RS, Brazil. The fruiting organs of the pear trees 'Garber' that showed the highest effective fruit set rates were brindille couronnee and bourses. Lamburde was the fruiting organ with the lowest effective fruit set rates independent of treatment.

This research work has evaluated the effects of gibberellic acid, bio-stimulant Crop Set, and girdling applied during bloom and post-bloom stages on yield and quality of the marketable bunches of seedless grape 'Catalunha' in the Sao Francisco River Valley, Northeast of Brazil. The trial was carried on throughout two harvest seasons (2001-2002), in the Bebedouro Experimental Field, Embrapa Semi-Arido, Petrolina-PE, Brazil. The trial was laid out in a randomized complete block design with three replicates, each replicate consisting of a four-tree plot. The treatments were: one level of gibberellic acid split in five applications (10 + 15 + 15 + 50 + 50 mg.L -1 ), two levels of Crop Set (0.1 and 0.2%) and trunk girdling, isolated or combined with the other treatments. In 2001, the maximum values for weight, length and diameter of berry were observed with girdling + gibberellic acid and girdling + gibberellic acid + Crop Set at 0.1% treatments. The treatments girdling and Crop Set when applied isolated and/or combined to each other did not increase the berry size. In 2002, the treatments girdling + gibberellic acid and girdling + gibberellic acid + Crop-Set at 0.2% promoted larger berries, increasing berry length by 32%.

This paper overviews the research on fruit size in litchi, an arillate fruit species. Factors affecting fruit size such as genetic characteristics, pericarp development, cytological basis, temperatures, water regime, phytohormones, nutrients, plant regulators, surgical operations such as pruning, girdling or bark ring incision etc., and crop load are discussed.

The discovery of potassium chlorate (KClO 3 ) as flower inducing agent in longan (Dimocarpus longan Lour.) has overcome the problem of irregular bearing and enables farmers to produce this fruit crop in off-season. However, the underlying physiological mechanism of how this chemical triggers flower induction (FI) remains unclear. A possible explanation might be the timely hormonal changes in longan leaves during the transitional growth stage from vegetative to floral buds following KClO 3 application. The experiment consisted of a control treatment and four treatments with KClO 3 application; (1) no shoot girdling and no defoliation, (2) shoot girdling and removal of all leaves and petioles above the girdle, (3) shoot girdling without defoliation above the girdle and (4) apical defoliation without girdling. All shoot treatments were applied to each of twenty mature trees. KClO 3 was applied as soil drench at mature leaf stage in September 2007. The girdle was 2 mm wide and applied at about 10 cm below the shoot tip. Leaf samples for analysis of diffusible and extractable plant hormones were collected 8 times at 1- to 3-day intervals until 28 days after treatment (DAT). The concentration of endogenous hormones such as indole-3-acetic acid (IAA), gibberellins (GA 1, 3,20 measured as GA 3 equivalents), and the cytokinins isopentenyladenin/isopentenyladenosin (iP/ [9R] iP) and trans-zeatin/t-zeatin riboside (Z/ [9R] Z) were determined in leaves. The results show that IAA concentrations in leaves of all treatments were slightly reduced between 4 to 13 days following KClO 3 application but values remained rather constant thereafter. In general, leaves above the girdle had significantly higher concentrations of iP/[9R]iP but less Z/[9R]Z whereas the export of diffusible iP/[9R]iP from upper leaves of non-girdled shoots increased from 10 to 13 days after application.

As for many other fruit trees originating from subtropical climates, cool temperature is a key trigger of flower induction (FI) in litchi and longan. However, the expansion of fruit growing areas to lower, more tropical latitudes renders FI more unreliable, due to the lack of sufficient cool temperatures, and causes problems with alternate bearing behaviour. Fortunately, in the advent of inadequate low temperatures, it is now possible to force FI at least for longan (Dimocarpus longan Lour.) through the application of KClO 3 , allowing the production of off-season fruit. In contrast, there are with the exception of stem girdling currently no FI techniques for litchi (Litchi chinensis Sonn.). Consequently longan became an ideal model plant for our investigations on the hormonal regulation of FI. By comparing hormonal data from KClO 3 -induced field-grown longan trees with those of cool temperature induced litchi trees in growth chambers, we attempt to derive the essential hormonal changes for FI. In a first plant response, all inductive treatments/conditions resulted in a significant reduction of leaf photosynthesis. In KClO 3 induced longan as well as in litchi following cool temperature treatment a clear increase of cytokinin (CK) concentrations in buds is found with a concomitant reduction in concentrations of gibberellins (GAs) and auxin (IAA). Whether the raised levels of CKs in buds derived from elevated concentrations of CKs in bark and wood as a consequence of deconjugation or originated from de novo biosynthesis in the roots remains unclear. It can also not be concluded if GAs exerts their FI inhibiting effect directly or through crosstalk with IAA metabolism and therefore help to maintain the CK/IAA ratio at a level which favours floral development. However, knowing which sequence of hormonal events is necessary to induce flowering could help to develop new strategies of smart crop manipulations to improve FI and to achieve off-season production even in litchi.

Prohexadione-Calcium (P-Ca) is a promising new shoot growth retardant that is already registered on apples in North America (Apogee ® ) and in Europe (Regalis ® ). This gibberellin biosynthesis inhibitor with limited persistence and low toxicity was tested on five Pyrus communis cultivars: ‘Rosemarie’, ‘Flamingo’, ‘Early Bon Chretien’, ‘Packham’s Triumph’ and ‘Forelle’. P-Ca was able to reduce shoot growth in all of the cultivars, but there was a marked difference in sensitivity towards different rates of P-Ca between the different cultivars. Fruit set was improved in ‘Rosemarie’, ‘Forelle’ and ‘Early Bon Chretien’, which led to a decrease in final fruit size of ‘Rosemarie’. P-Ca caused a decrease in return bloom in ‘Packham’s Triumph’ and ‘Forelle’. Girdling only reduced shoot growth in ‘Forelle’ but did not improve fruit set in any of the cultivars. Girdling improved final fruit weight of ‘Flamingo’, increased fruit length in ‘Early Bon Chretien’ and increased return bloom in all of the cultivars except ‘Packham’s Triumph’. The five cultivars are categorised according to their sensitivity towards P-Ca: ‘Rosemarie’ > ‘Flamingo’ = ‘Early Bon Chretien’ = ‘Packham’s Triumph’ > ‘Forelle’. INTRODUCTION Controlling excessive vegetative growth in fruit trees is very important (Costa et al., 2002; Forshey and Elfving, 1989; Williams, 1984) as it is a strong sink that competes with the fruit on the tree. This competition is at its strongest during the first 50 days after full bloom when shoot growth is very rapid (Byers and Yoder, 1999; Elfving et al. 2002) and coincides with the cell division stage of fruit growth. This results in a decrease in the number of cells in the fruit and, therefore, fruit size (Cowan et al., 2001; Yamaguchi et al., 2002). Excessive shoot growth also has a negative effect on fruit quality, yield and pest control (Greene, 1999; Miller and Tworkoski, 2003). Shading caused by excessive shoot growth has a negative effect on flower bud induction and the quality of the return bloom (Greene, 1999; Miller and Tworkoski, 2003). One of the main methods to control shoot growth is pruning. Pruning, however, is a very expensive, labour intensive and time-consuming management practice (Byers and Yoder, 1999). Other control measures have been used e.g. ethephon applications, summer pruning, root pruning and dwarfing rootstocks, but all have negative side effects (Greene, 1999). Girdling is also a practice used in pear orchards to control shoot growth, increase fruit set and improve fruit quality (Ingels, 2002; Miller and Tworkoski, 2003; Wilton, 2000). Girdling affects assimilate partitioning and the flow of plant hormones and nutrients throughout the tree (Miller and Tworkoski, 2003). As gibberellins (GA) have been implicated in stem elongation (Owens and Stover, 1999) researchers have been looking at GA biosynthesis inhibitors to counteract these and thus reduce shoot growth (Miller, 2002; Unrath, 1999). Although many of these compounds inhibit shoot elongation (e.g. chlormequat, daminozide) their persistence in the tree is a big disadvantage (Owens and Stover, 1999). Prohexadione-calcium [(P-Ca); BAS-125 (3-oxido-4-propionyl-5-oxo-3cyclohexene-carboxylate)] is a GA biosynthesis inhibitor with low toxicity and limited persistence (Owens and Stover, 1999). The application of P-Ca reduces levels of GA1

To quantify the growth habit of locally important pear varieties, initially, 2-year-old pear branches were classified into groups based on the length and position of lateral shoots. Four groups were formed that ranged from cultivars with a spurred growth habit and strong apical control, to cultivars with a spreading growth habit and weak apical control. Secondly, the development of fruiting branches was observed for up to five years by observing the five developmental alternatives of the terminal buds of laterals, i.e., dormant, vegetative, reproductive without fruit, reproductive with fruit, and abortion. Under local conditions two general problems were observed. A large proportion of buds remain vegetative giving rise to poor flowering, and many buds remain dormant, probably due to the use of vigorous rootstocks and inadequate winter chilling. Local training systems address these shortcomings through the use of rest-breaking agents, girdling, and winter pruning techniques. Winter pruning strategies for locally important cultivars can be split into two broad approaches. In one approach spurs are renewed within spur systems primarily via bourse shoots. In the other approach spurs are renewed via year-old shoots. The motivation for the use of these systems is discussed in light of the above architectural findings.

The history of pear pruning and training under the hot and dry conditions in South Africa is discussed. Due to the poor soils and the need for irrigation the move towards highdensity plantings occurred with the continued use of the vigorous BP rootstocks. Planting densities have stabilized at ca. 4 x 1.5m (1667 trees/ha). Vigor in these plantings is managed through girdling and the manipulation of branching on young trees. These developments and technologies are discussed.

Even though several experiments have confirmed the promotional effect of girdling, application of morphactin or a combination of both on flower induction in mango trees, little is known about the physiological and hormonal changes induced by these treatments, which might be responsible for the transition from vegetative to generative bud development. Therefore, we mechanically girdled young, potted mango trees. Part of the girdled trees were additionally chemically girdled with two auxin transport inhibitors, viz. morphactin and naphthyl-phthalamic acid. Although none of the treatments induced flowering in the young trees, all treatments reduced photosynthesis, transpiration and stomata conductance for at least 14 days. Furthermore, a considerable increase in leaf polar IAA export could be measured, which, because of the restriction imposed by the mechanical / chemical girdle, could not reach the roots of the trees. Possibly as a result of this, cytokinins (CKs) in the xylem sap of the treated trees increased significantly. A hypothesis is presented trying to explain how IAA export from leaves and CKs from roots could induce mango trees to flower even under non-inductive temperatures.

‘Springcrest' covers an important period in the regional peach season, but its good performance is not supplemented by a satisfactory fruit size. An experiment was carried out in order to evaluate the effects of different cultural practices on fruit quality, yield and crop distribution. The treatments consisted in the use; alone or combined, of flower thinning, conventional fruit thinning (Control), girdling and 2,4 diclorophenoxypropionic acid butilglycolic ester (2,4-DP). The evaluated variables were yield, fruit weight, percentage distribution of fruit size and for each harvest, skin color, overcolor percentage, total soluble solids content (TSS), flesh firmness and titratable acidity. Those treatments which included flower thinning affected yield negatively. Girdling appears as a factor that softens these effects. Only conventional fruit thinning did not increase the fruit percentage harvested the first time. A positive effect on fruit size was observed in all treatments in comparison to the control. The application of 2,4 DP did not harm the yield in comparison with the control but it affected acidity and TSS. No treatment affected the color of the fruits.

The effects of thinning of fruits, girdling of branches and pinching of shoots were examined in four midseason-maturing peach cultivars on five dates in mid May and late June, the end of stage 1 and stage 2, respectively. The treatments on May 15 and May 28 promoted fruit growth, and markedly induced stone cracking but less so fruit abscission. On the whole, flesh of peach was firm in terms of the partial compressive strength, and osmotic pressure was low during late May and mid June. On the other hand, the amount of lignin in peach stone increased linearly and the maximum strain decreased gradually from late May to maturation. The rigidity of the stone expressed by the elastic modulus increased during late May and early June, and the stone became hard until maturation as indicated by the partial compressive strength. These results showed that stone became brittle but crisp during early stage 2. Therefore, the growth of peach treated in late stage 1 and early stage 2 increased markedly, and the radial tensile force of the flesh would produce cracks in the stone. Differences in mechanical properties were observed among the cultivars, for example, a higher elastic modulus in the stone of 'Hakuho' and smaller partial compressive strength in the stone of 'Ohkubo'. Differences were also observed in the treated plots such as increased tensile strength, plasticity and Young’s modulus in the flesh of 'Beni-shimizu'.