TREE SIZE CONTROL IN MANGO (MANGIFERA INDICA L.) - SOME CONSIDERATIONS

Pruning is an unavoidable necessity of virtually all arboreal fruit crops. In the tropics and subtropics, pruning of mango (Mangifera indica L.) is particularly important due to its tendency for frequent flushes, especially in humid tropics. Commercial orchards must maintain control of both tree size and orchard productivity in order to remain productive. Tip, formation, and severe pruning can be used in a variety of circumstances to produce predictable and useful results for a variety of purposes. For example, tip pruning can be used to encourage frequent flushing and branching of young trees to bring them into commercial production years earlier than if left alone. It can also stimulate timely flushes of lateral stems in an annual program to maintain tree size and prepare trees for synchronous flowering. Formation pruning shapes trees in an overgrown orchard to receive the maximum amount of light for high productivity and sets them up for annual pruning in a flowering management program. Severe pruning coupled with subsequent tip pruning of huge, nonproductive trees facilitates rapid restoration of orchard production. Each of these types of pruning can be used to get mango trees into production quickly and thereafter maintain maximum annual production while maintaining their desired size.

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SESSION—IX - SPECIAL PROBLEMS - I) TREE SIZE CONTROL

Acta Horticulturae ◽

10.17660/actahortic.1989.231.66 ◽

1989 ◽

pp. 897-897

Author(s):

Dr. K.S. Chauhan ◽

Dr. R.N. Pal

Keyword(s):

Size Control ◽

Tree Size

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Half-topping 'A4' macadamia trees has a markedly different effect on yield than full-topping

Australian Journal of Botany ◽

10.1071/bt16065 ◽

2016 ◽

Vol 64 (8) ◽

pp. 664 ◽

Cited By ~ 1

Author(s):

Trevor Olesen ◽

David Robertson ◽

Alister Janetzki ◽

Tina Robertson

Keyword(s):

Substantial Reduction ◽

Size Control ◽

Tree Size ◽

First Year ◽

Industry Practice ◽

Second Year ◽

Effect On Yield ◽

Control Tree ◽

Western Half ◽

Yield Penalty

Mechanically hedging the tops of macadamia trees to control tree size is referred to as topping. Topping the entire upper canopy causes a substantial reduction in yield and is not a recommended industry practice. Here we compare topping just half the upper canopy with full-topping, and with control trees that were not pruned, to test whether half-topping is a more acceptable means of size control, with less of a yield penalty. We used macadamia cultivar ‘A4’ as the subject for the study. The trees were topped horizontally at anthesis. Full-topping reduced yields by 78% in the first year and 63% in the second year compared with the control trees. By the end of the second year the height of the fully-topped trees was approximately the same as that of the control trees. In contrast, topping just the western half of the upper canopy resulted in little yield penalty. Yields were reduced non-significantly by 14% in the first year, and negligibly in the second year, compared with the control trees; and by the end of the second year, the regrowth on the topped halves of the trees was only two-thirds the height of that on the full-topped trees. The results are encouraging because topping is simple and cheap, and would be an attractive tree size control option for growers at the yield penalty described here for the half-topped treatment.

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Production Trends in Mature Macadamia Orchards and the Effects of Selective Limb Removal, Side-hedging, and Topping on Yield, Nut Characteristics, Tree Size, and Economics

HortTechnology ◽

10.21273/horttech.23.1.64 ◽

2013 ◽

Vol 23 (1) ◽

pp. 64-73 ◽

Cited By ~ 4

Author(s):

Lisa McFadyen ◽

David Robertson ◽

Margaret Sedgley ◽

Paul Kristiansen ◽

Trevor Olesen

Keyword(s):

Substantial Reduction ◽

Size Control ◽

Cost Effective ◽

Tree Size ◽

Macadamia Integrifolia ◽

Effective Removal ◽

Effect On Yield ◽

Yield Trends ◽

Disease Pressure

Yields of macadamia (Macadamia integrifolia, M. tetraphylla, and hybrids) orchards tend to increase with increasing tree size up to ≈94% light interception. Beyond this, there is some indication that crowding leads to yield decline, but the evidence is limited to one site. Increasing tree size and orchard crowding also present numerous management problems, including soil erosion, harvest delays, and increased pest and disease pressure. The aim of this study was to better characterize long-term yield trends in mature orchards and to assess the effects of manual and mechanical pruning strategies on yield, nut characteristics, tree size, and economics. We monitored yield at four sites in mature ‘344’ and ‘246’ orchards for up to seven years and confirmed a decline in yield with crowding for three of the sites. There was a small increase in yield over time at the fourth site, which may reflect the lower initial level of crowding and shorter monitoring period compared with the other sites, and highlights the need for long-term records to establish yield trends. Pruning to remove several large limbs from ‘246’ trees to improve light penetration into the canopy increased yield relative to control trees but the effect was short-lived and not cost-effective. Removal of a codominant leader from ‘344’ trees reduced yield by 21%. Annual side-hedging of ‘246’ trees reduced yield by 12% and mechanical topping of ‘344’ trees caused a substantial reduction in yield of up to 50%. Removal of limbs in the upper canopy to reduce the height of ‘344’ trees had less effect on yield than topping but re-pruning was not practical because of the extensive regrowth around the pruning cuts. Tree size control is necessary for efficient orchard management, but in this study, pruning strategies that controlled tree size also reduced yield. Research into the physiological response to pruning in macadamia is required to improve outcomes.

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Transformation of `Bosc' Pear (Pyrus communis L.) with the rolC Gene from Agrobacterium rhizogenes and Characterization of Transgenic Plants

HortScience ◽

10.21273/hortsci.33.3.461c ◽

1998 ◽

Vol 33 (3) ◽

pp. 461c-461

Author(s):

Ralph Scorza ◽

Richard L. Bell ◽

Chinnathambi Srinivasan ◽

Kevin Webb

Keyword(s):

Plant Growth ◽

Genetic Transformation ◽

Genetic Improvement ◽

Size Control ◽

The United States ◽

Tree Size ◽

Native Promoter ◽

Pyrus Communis L ◽

Size Controlling

Pear production in the United States relies on a few major cultivars, including `Bosc'. While there is a need for new cultivars, genetic improvement of the existing major cultivars through genetic transformation could have a major impact on the industry. We have developed a system for regeneration and transformation of pear. While the major objective of the transformation project is to improve resistance to fire blight (Erwinia amylovora) in major pear cultivars, tree size control is also one of the objectives in the genetic improvement of pear that may be approached through transformation. Traditionally, manipulation of tree size and vigor in established cultivars has been achieved through the use of size-controlling rootstocks. There are no completely satisfactory size-controlling rootstocks for pear. Genetic transformation provides an approach to developing new size-controlling rootstocks and also to directly affect the growth of the transgenic scion cultivar using genes that affect plant growth such as the rolC gene isolated from the bacterium A. rhizogenes, the causal agent of “hairy root” disease. This gene has been shown to alter growth and development in a number of plant species. To investigate the potential utility of the rolC gene in altering the growth of pear trees, `Bosc' pear was transformed with A. tumefaciens EHA101 carrying a pGA482-based plasmid containing the NPTII and GUS genes, and the rolC gene under the control of its native promoter. Four clones were isolated that were kanamycin-resistant and GUS-positive. PCR assays and DNA blots indicated the presence of the rolC gene in these clones. Each transgenic clone has been multiplied in vitro and planted in the greenhouse where transgene expression and plant growth are being evaluated.

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Field Evaluation of 64 Rootstocks for Growth and Yield of ‘Kensington Pride’ Mango

HortScience ◽

10.21273/hortsci.43.6.1720 ◽

2008 ◽

Vol 43 (6) ◽

pp. 1720-1725 ◽

Cited By ~ 13

Author(s):

Malcolm W. Smith ◽

Jeremy D. Bright ◽

Mark D. Hoult ◽

Richard A. Renfree ◽

Tony Maddern ◽

...

Keyword(s):

Mangifera Indica ◽

Morphological Characteristics ◽

Tree Canopy ◽

Early Years ◽

Tree Size ◽

Growth And Yield ◽

High Yield ◽

Subsequent Performance ◽

Yield Efficiency ◽

Wide Range

Despite an abundance of polyembryonic genotypes and the need for rootstocks that improve scion yield and productivity, simultaneous field testing of a wide range of mango (Mangifera indica L.) genotypes as rootstocks has not previously been reported. In this experiment, we examined the growth and yield of ‘Kensington Pride’ on 64 mango genotypes of diverse origin during the first four seasons of fruit production to identify those worth longer-term assessment. We also recorded morphological characteristics of seedlings of 46 of these genotypes in an attempt to relate these measures to subsequent field performance. Tree canopy development on the most vigorous rootstocks was almost double that on the least vigorous. Growth rates differed by more than 160%. Cumulative marketable yield ranged from 36 kg/tree for the lowest yielding rootstock to 181 kg/tree for the most productive. Yield efficiency also differed markedly among the 64 rootstocks with the best treatment being 3.5 times more efficient than the poorest treatment. No relationship was found between yield efficiency and tree size, suggesting it is possible to select highly efficient rootstocks of differing vigor. Two genotypes (‘Brodie’ and ‘MYP’) stood out as providing high yield efficiency with small tree size. A further two genotypes (‘B’ and ‘Watertank’) were identified as offering high yield efficiency and large tree size and should provide high early yields at traditional tree spacing. Efforts to relate the morphology of different genotype seedlings to subsequent performance as a rootstock showed that nursery performance of mango seedlings is no indication of their likely behavior as a rootstock. The economic cost of poor yields and low yield efficiencies during the early years of commercial orchard production provide a rationale for culling many of the rootstock treatments in this experiment and concentrating future assessment on the top ≈20% of the 64 treatments. Of these, ‘MYP’, ‘B’, ‘Watertank’, ‘Manzano’, and ‘Pancho’ currently show the most promise.

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THE INFLUENCE OF TREE SIZE CONTROL AND PLANT DENSITY ON CITRUS PRODUCTIVITY

Acta Horticulturae ◽

10.17660/actahortic.1986.175.36 ◽

1986 ◽

pp. 249-254 ◽

Cited By ~ 3

Author(s):

R.J. Hutton

Keyword(s):

Plant Density ◽

Size Control ◽

Tree Size

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Interfacial studies in Nb3Sn superconductors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100087264 ◽

1991 ◽

Vol 49 ◽

pp. 590-591

Author(s):

Ernest L. Hall ◽

Lee E. Rumaner ◽

Mark G. Benz

Keyword(s):

Grain Size ◽

Grain Boundaries ◽

Flux Pinning ◽

Size Control ◽

High Magnetic Fields ◽

Type Ii ◽

Reaction Interface ◽

Liquid Diffusion ◽

Type Ii Superconductor ◽

Grain Size Control

The intermetallic compound Nb3Sn is a type-II superconductor of interest because it has high values of critical current density Jc in high magnetic fields. One method of forming this compound involves diffusion of Sn into Nb foil containing small amounts of Zr and O. In order to maintain high values of Jc, it is important to keep the grain size in the Nb3Sn as small as possible, since the grain boundaries act as flux-pinning sites. It has been known for many years that Zr and O were essential to grain size control in this process. In previous work, we have shown that (a) the Sn is transported to the Nb3Sn/Nb interface by liquid diffusion along grain boundaries; (b) the Zr and O form small ZrO2 particles in the Nb3Sn grains; and (c) many very small Nb3Sn grains nucleate from a single Nb grain at the reaction interface. In this paper we report the results of detailed studies of the Nb3Sn/Nb3Sn, Nb3Sn/Nb, and Nb3Sn/ZrO2 interfaces.

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