Tree Training Systems Research Articles

TREE JOINTING AND BRANCH BENDING INFLUENCE ENDOGENOUS LEVELS OF HORMONES AND FLOWERING IN JAPANESE PLUM 'KIYO'

The joint tree training system was developed in Japan as a horticultural intervention to promote flower induction (FI) in fruit trees. In this system, the apical tip of one tree is artificially grafted into the bent main stem of another in a row of three or more trees. The system reportedly facilitates faster establishment of the tree framework leading to faster FI and high productivity of the orchard earlier than those utilizing traditional systems. Plant hormones are putative bio regulators of flower induction and development. However, changes in phytohormone levels as a result of this cultural intervention have not been reported. To investigate this, 5-year old trees of 'Kiyo' Japanese plum (Prunus salicina) in containers were either bent and jointed into a row of three trees (Bent-Joint group), or individually bent (Bent group). Upright individual trees served as control. Young leaves were analyzed for phytohormone content by ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). Our results showed that both the Bent and Bent-Joint groups have significantly lower concentrations of the bioactive gibberellins (i.e., GA1, GA3 and GA4), but higher abscisic acid (ABA) content compared to the control. Consistent with the implicated role of GA as suppressor, and ABA as inducer of FI, both the Bent and Bent-Joint groups registered high flowering rates. Fruit-set was also observed in these groups, while the control had none. The number of new shoots did not significantly vary across treatment groups. Yet control trees, having relatively high bioactive GAs and low ABA contents, exhibited the most vigorous shoot elongation. These findings suggest that the joint tree training system appear to favor FI and fruit-set over vegetative growth that may have resulted from the observed low levels of bioactive GAs and high ABA content.

Early performance of cv. Jonagold apple on M.9 in five tree training systems

The effects of five training systems on tree growth, fruit yield and some fruit characteristics were assessed in Jonagold apple cv. grafted on M.9 rootstock. The trees were trained in one of five ways: slender spindle (SS; 4,761 trees/ha), vertical axis (VA; 2,857 trees/ha), hytec (HT; 1,904 tree/ha) and two different tree densities of super spindle (L-Super S with 5,000 trees/ha; H-Super S with 10,000 trees/ha). Trunk cross-sectional area (TCA) was higher in HT and VA than SS, L-Super S and H-Super S in the 4<sup>th</sup> year. While HT had the highest cumulative yield/tree, the lowest cumulative yield was observed in H-Super S. Although HT had the highest yield/ tree, it ranked the last in cumulative yield efficiency (CYE) due to high TCA. The highest (CYE) was measured in trees trained as L-Super S. When cumulative yields (CY)/ha were evaluated, the yield advantage of high density planting was clearly evident for the first three cropping years. H-Super S systems (10,000 trees/ha) had the highest CY/ha and achieved a yield of 91.24 t/ha in year 4. HT (1,904 trees/ha) had the lowest CY/ha (33.46 t). Training systems had no consistent effect on average fruit diameter, weight, firmness, soluble solid and titratable acidity.  

Influence of Training System on Volatile and Sensory Profiles of Primitivo Grapes and Wines

The enhancement of grape aroma and the investigation of the relationships between grape and wine composition are important given the growing interest in wines with distinctive varietal character. Each training system involves specific grapegrowing conditions, which affect the concentration of volatile metabolites of grape. The aim of this work was to evaluate the influence of three training systems, including little tree, bilateral Guyot, and four rays, on the volatile composition of Primitivo grape and on the volatile composition and sensory properties of the corresponding wine in Apulia region of Italy. Free and bound volatile fractions were evaluated by gas chromatography coupled to mass spectrometry. Sensory analysis was performed by a panel of trained judges. Results showed that the little tree and bilateral Guyot training systems improved the accumulation of aroma precursors and volatile compounds in grape and wine and the sensory characteristics of the wine.

Spur behaviour in almond trees: relationships between previous year spur leaf area, fruit bearing and mortality

In mature almond (Prunus dulcis) orchards, the majority of crop is borne on spurs (short, proleptic shoots) that can live for several years and can produce from one to five fruits. Previous research has led to the hypothesis that spur longevity is related to spur light exposure, cropping and age. However, limited quantitative data are available to substantiate these hypotheses. The objective of this study was to determine spur characteristics that were most highly correlated with spur productivity and longevity in mature, bearing almond trees. Previous year spur leaf area was strongly related to spur viability and flowering; the greater the leaf area in the previous year, the higher the probability of spur survival into the next year and the higher the probability for the spur to bear one or more flowers. Previous year bearing also appeared to influence viability and return bloom, especially in spurs with low leaf area. These results suggest that spur source-sink balance is basic to the life cycle of almond spurs. Furthermore, the results are consistent with the hypothesis that spurs are semi-autonomous organs with respect to carbohydrate balance for much of the growing season. Finally, this information provides general thresholds for maintaining spur viability and productivity that will be useful for developing and evaluating tree training systems and orchard management practices.

Flowering and fruit set in cherimoya (Annona cherimola Mill.) as affected by the tree-training system

SummaryManagement of flowering and fruit set are of prime importance in order to obtain high yields in cherimoya (Annona cherimola Mill.) due to floral dichogamy. This phenomenon is largely dependent on environmental conditions such as temperature, relative humidity, and light intensity, which usually make hand-pollination of flowers necessary in order to achieve acceptable levels of fruit set and yield. Nevertheless, these factors can be modified by means of the growing system. In this work, we studied the effects of two tree-training systems on the environment inside the canopy, on flowering, on pollination, and on fruit set in mature ‘Concha Lisa’ cherimoya trees. The open-centre vase training system (6 m 4 m) and the high-density slender-spindle (tunnel) training system (4 m 1 m) were used. The high-density tunnel training system increased the relative humidity, as well as reducing the temperature and the level of photosynthetically active radiation, inside the canopy, which resulted in an earlier onset of the male floral stage and in an extended maintenance of the highly-receptive female stages. This resulted in an overlap of the sexuallycompatible floral stages, thus increasing the incidence of natural cross-pollination and maintaining the viable, receptive sexual stages and pollen, over time, to improve hand-pollination.

A SURVEY OF CULTIVARS AND MANAGEMENT PRACTICES IN AUSTRALIAN PERSIMMON ORCHARDS

Three surveys were conducted to determine the most commonly used cultivars and management practices across Australia. The persimmon industry is established from the semi-tropical far north of Queensland to the cool temperate zones of Victoria, South Australia and Western Australia. Fruit from warmer regions mature four months earlier, giving a harvest spread from February to June inclusive. The majority of the Australian industry is based on the non-astringent cultivar Fuyu. Only 26% of Australian orchards are planted with pollinizers. Yield and fruit size vary within and between regions. Factors contributing to lower yields and smaller size grades are temperature, salinity, pollination, and training and management systems. The most common tree training system is the freestanding vase, followed by palmette, then V- and Tatura trellises. Ruakura trellis is the least used. Trellised trees produce higher yields of marketable fruit through increased planting density, improved light interception and a tree structure that stabilises against tree movement, significantly reducing fruit blemish.

Canopy Growth, Yield, and Fruit Quality of 'Royal Gala' Apple Trees Grown for Eight Years in Five Tree Training Systems

In 1993, a planting of virus-free 'Royal Gala' apple (Malu×domestica Borkh.) on 'M.9' rootstock was established at Summerland, B.C., Canada, to determine whether angled-canopy training systems could improve orchard tree performance relative to slender spindles. The trees were trained in one of five ways: slender spindle (SS), Geneva Y-trellis (GY), a modified Solen training we called 'Solen Y-trellis' (SY), or V-trellis (LDV), all at the same spacing (1.2 m × 2.8 m), giving a planting density of 2976 trees/ha. In addition, a higher density (7143 trees/ha) version of the V-trellis (HDV) was planted to gauge the performance of this system at densities approaching those of local super spindle orchards. The plots were drip-irrigated and hand-thinned. No summer pruning was done. After 8 years, differences among training systems at the same density and spacing were small and few. The two Y-shaped training systems had 11% to 14% greater cumulative yield/ha than the SS, but did not intercept significantly more light at maturity. No consistent differences occurred in fruit size or the percentage of fruit with delayed color development among the four training systems at the same density. Relative to the LDV, the HDV yielded less per tree, but far more per hectare, particularly in the first 3 years. After 8 years, the cumulative yield/ha was still 65% greater than with LDV. Yield efficiency was unaffected by tree density. Fruit size on HDV ranked lowest among the systems nearly every year, but was still commercially acceptable. The HDV intercepted more light (73%) than SS (53%). The percentage of fruit with delayed color development in HDV was not significantly different from that for LDV in most years. The trees in HDV were difficult to contain within their allotted space without summer pruning. The substantially similar performance of all the training systems (at a given density, and with minimal pruning) suggests that cost and ease of management should be the decisive factors when choosing a tree training method.

A SYSTEMS APPROACH TO ROBOTIC BULK HARVESTING OF APPLES

A unique robotic bulk harvester was conceived and developed to remove apples grown on narrow inclined trellises. The system combined mechanical harvesting technology with sensors and intelligent adaptive technology to identify an individual branch, determine fruit locations, position a Rapid Displacement Actuator (RDA) and a catching surface under the apples, and execute the RDA. Detachment was effected by rapidly displacing the limb away from the fruit. Requirements for a compatible tree training system were developed. Field testing demonstrated feasibility of the complete system. Fruit removal averaged 95% and detached fruit graded 99% U.S. Extra Fancy. Factors were identified to improve all aspects of the system and will require additional research.

Light Distribution in Three Apple Training Systems as Affected by Cultivar and Rootstock

Light distribution in two cultivars on three dwarfing rootstocks in three high-density apple tree training systems was measured in the sixth leaf beginning at full bloom and continuing through the season. Training system had a significant effect on light penetration into the lowest point of the canopy (measured at 0.5 m), with the slender spindle being significantly darker than either the central leader or the vertical axis, although all three systems were below the threshold value of 30% full sun (FS) needed to maintain productivity for most of the season. Cultivar had no significant effect; however, trees of both `Jonagold' and `Empire' fell below 20% FS early in the season and remained there until late in the season. Rootstock had the greatest effect, with trees on M9 and M26 being significantly darker in the lower canopy than trees on Mark. Trees on M26 and M9 fell below 10% FS early in the season and remained there, while trees on Mark never fell below 20% FS.

Light Thresholds for Apple Tree Canopy Growth and Development

Understanding canopy development of fruit trees is important to their management. The tree canopy physically supports the fruit crop. The leaf canopy intercepts light and produces carbohydrates used in growth and metabolic activity, Light distribution within the canopy affects fruit color and quality, and the rate and timing of canopy development affects pest infestation and control. Ultimately, then, canopy development relates to crop quantity and quality and, thus, economic yield of an orchard. The challenge to horticulturists is to manipulate and manage the tree canopy to maximize economic production. Light is an important aspect of canopy studies because of its role in photosynthesis, its function in developmental morphology of leaves and shoots, its role in flower initiation and fruit set, and its importance to fruit development and quality. Because effects of light can be influenced by the tree training system, pruning, or other mechanical means, such as shading, the question arises, How much light is needed to maximize orchard performance? The purpose of this paper is to review some of the relationships of light to apple tree physiology and performance. Two aspects of light and tree canopy development must be considered. First, interception of available light by the total orchard canopy is correlated to total biomass production of the crop system (Monteith, 1977). Second, penetration and/or distribution of light within a single tree canopy must be optimized for maximum tree performance and crop development.

Spray Chemical Deposits in High-density and Trellis Apple Orchards

Abstract Chemicals deposited on foliage varied by a factor of three to five times when sprays were applied with an airblast sprayer to apple (Malus domestica Borkh.) trees in various training systems. Deposits were higher with vertical than horizontal training systems, smaller tree sizes, and less-dense tree canopies of spur-type trees. The Lincoln canopy tree training system prevented good spray penetration because the airblast spray pattern was split by the horizontal nature of the canopy.