Field Invenation

BACKGROUND OF THE INVENTION

In the field of industrial fruit growing, growers buy young trees from tree nurseries (nursery trees) for planting or re-planting orchards. It is of the utmost importance to develop nursery trees that have a maximum fruit-bearing capacity at the start of their growth in the orchard, which will be maintained during the life of the tree (typically 10 or more years).
Fruit nursery trees for commercial fruit production traditionally
consist of a rootstock onto which a scion is grafted or budded (sometimes, also a so-called ‘interstock’ is placed between the rootstock and the scion, particularly when graft-incompatibility between rootstock and scion is suspected). The rootstock interacts with the soil and influences the tolerance of the tree against biotic and abiotic stress factors as well as its growth habitus and the fruit quality. The scion consists of the variety with the desired fruit characteristics. Several horticultural methodologies for producing fruit nursery trees are known in the art and traditionally use intervention onto the tree structure by e.g. cutting out, pruning or defoliation. An often used fruit nursery tree type is the so-called “knip boom” or “knip tree”. The “knip” tree is a two-year old fruit tree with a one-year-old crown. The name “knip” (Dutch for ‘cut’) stems from the cutting of the tree after one year at about 50 to 80 cm above the ground, depending on the variety. In the next year, the top bud is promoted to create a central leader on which sylleptic shoots will form branches which will bear the fruit, having an implantation angle of almost 90° with respect to the stem. The more horizontally growing branches will produce the most fruit, while the more vertically growing branches will grow faster and hence produce more wood (so-called “suckers”). These “suckers” drain the energy from the plant, which could otherwise go to fruit production.
Manipulation of tree architecture in the nursery stage appears to determine the way the tree will further develop in its later life and is currently subject of extensive research and] The goal of the present invention is to provide nursery trees as starting material for establishing fruit production orchards, such nursery trees overcoming the drawbacks of the known fruit nursery trees in terms of the start and maintenance of the productivity in the orchard.

SUMMARY OF THE INVENTION
The present invention provides a new tree (referred to herein as “new tree”), which has been manipulated at the nursery stage in order to obtain nursery trees that will, upon planting in an orchard, have an optimal fruit bearing capacity, starting earlier in the productive life of the tree and being maintained throughout its life time.

The invention provides:
1.1. A nursery fruit tree having an optimal fruit/wood production balance having the following characteristics: preferred height of the tree between 1.8 and 2.7 m, crowns of productive branches at three levels, separated by windows sufficiently large to enable optimal light provision for production and ripening of the fruit, a preferably uncut main stem the inclination of the side branches versus the stem approaching 90°.
2.2. Preferably, the invention provides the nursery fruit tree according to point 1, wherein: said first branching level is situated at a height of about 25 to 35 % of the tree, said second branching level is situated at a height of about 40 to 55 % of the tree height, said third branching level is situated at a height of about 60 to 70 % of the tree height.
3.3. Preferably, the invention provides the nursery fruit tree according to points 1 or 2, comprising sylleptic shoots
for the 1stand the 3rd branch level and proleptic shoots for the 2nd branch level.
4.4. The invention further provides a fruit tree grown from a nursery fruit tree according to any one of points 1 to 3, preferably an orchard fruit tree.
5.5. The invention further provides a method for obtaining a nursery fruit tree with optimal balance between fruit and wood production, comprising the steps of:
1.1) planting a scion of the desired fruit producing variety that has been united with a suitable rootstock or rootstock-interstock,
2.2) during the first growth year:
harmonizing the length of the growing trees and creating a first branching level by inducing branching at the top of the tree,by adding growth regulators when the height of the tree reaches about 20 to 35 % of the desired final height, growth inhibition of main stem, by applying a growth inhibitor when the height of the tree reaches about 40 to 55 % of the desired final height, selective inhibition of side branching.
3.3) during the second growth year: cutting away the branches competing with the top of the tree above the second branching level, stimulating elongation and/or induction of proleptic side branches at the second level and/or first branching level, inducing branching at the top of the tree to create a 3rd branching level when the tree reaches a height of about 55 to 70 % of the desired final height, and inhibiting growth of side branches at 1st, 2nd and 3rd level. Preferably, the invention provides the method according to points 5 or 6, wherein, a selective inhibitor of the growth of the main stem and/or side branches The new tree according to the present invention has several potential advantages over the known knip tree as is outlined in Table 1 below.