Several dozen different forms of crowns can be found in European orchards; only a few of them are applicable to us.
The forms of fruit trees are divided into several groups according to four criteria:
– the shape of the cross section: circular, oval and row;
– branch arrangement: whorls, bunk, loose-story, non-storied and combined;
– the presence of a guide: guidebooks, wireless and with quick reference guide;
– branch system: almost natural, Untethered, adjustable and artificial.
Characteristics of circular crowns, oval and rows
Trees that grow naturally form circular crowns . Trees that are cut strongly on both sides take an oval shape. Linear form, having the shape of an elongated rectangle in cross section, is obtained by bending the shoots and fixing them in one, vertical plane.
Many different lined forms are known. In Poland they are so far not very common and therefore they should be discussed in more detail. Lane crowns were first formed in palace gardens by spreading tree branches on brick fences, surrounding gardens. With time, crowns on scaffolding made of posts and horizontal wires stretched between them began to be unbuttoned. The cultivation of trees in this form was popular in Italian gardens, English, and, above all, French. After World War II, the first ones were established in Poland, experimental lane quarters in Górna Niwa, near Puławy. It was founded by Stanisław Zaliwski. In commercial courts, lined forms began to spread in the early 1950s, first in Italy, and later in France, Bulgaria, Yugoslavia and other southern European countries. The lane forms enabled the intensive production of fruit obtained from vigorously growing trees, ennobled on seedlings.
The cultivation of vigorously growing and semi-dwarf trees in a lane form shows some advantages over circular forms. The trees formed in the lane can be planted more in the area of one hectare of orchard than circular trees, for example, apple trees that grow vigorously require a spacing of 6-8 m between rows and 4-6 m in rows, which means, that on 1 hectare can be planted from 200 into 400 trees. Lined-shaped apple trees require spacing 4 m between the rows and 4-6 m in the rows. On 1 hectare can be planted from 400 into 600 trees.
Many years of research conducted at the Institute of Pomology and Floriculture and abroad have shown, that young trees, both circular and lane, have a similar fertility. The fruit yield per hectare of orchards is proportional to the number of trees. Thus, a young row orchard can be used to harvest higher yields than a young orchard with circular crowns.
As the trees grow in the orchard, the yield of each circular tree increases rapidly, because each of them grows freely in all directions. On the other hand, the yield of an individual lane tree grows much slower, because his height is strictly regulated. Row trees reach the upper limit of fertility early. In 12-15 years after the orchard was established, both forms of the crown began to produce similar yields per hectare. Until then, with 1 hectare of row orchard can harvest 20-40 tons of apples more than 100% 1 ha of the orchard with circular crowns (table).
Table. Influence of the crown form and apple tree planting density on the fruit yield per tree and orchard hectare. The orchard was founded in the fall 1966 r. in SZD Dąbrowice (according to A. Mickey and D. Chlebowska)
| Variety | The sum of the apple yield for 9 lat (1971-79) in kg / tree | The sum of the apple yield for 9 lat (1971-79) in t/ha | Difference
t / ha |
||
| line form (4X3 m) | form
clatter (6X4) |
line form (4X3 m) | form
clatter (6X4) |
||
| Wealthy | 283 | 453 | 236 | 189 | 47 |
| Jonathan | 282 | 492 | 235 | 205 | 30 |
| Blackjon | 274 | 506 | 228 | 211 | 17 |
The second advantage of the row orchard is the easier access to trees from both sides of a flat wall. If there is a line 1,5 m in thickness, it is possible to reach into the center of the crown within the distance of an outstretched arm. Handwork like cutting, thinning out the fruit buds and picking the fruit are easier. Work on the upper parts of the crowns can be performed from movable platforms, moving along the inter-rows. The crowns of circular trees are easily accessible until the trees are young, and the sizes of the crowns are small. In an elder orchard, the worker will not reach into the crown with his hand, unless it comes between the boughs. The work is then less efficient and more strenuous. The possibilities of mechanization of works are smaller here. The two advantages of the row orchard described above are visible mainly in the sunny climate of southern Europe. In conditions of strong sunlight, the distances between the rows of lane trees may be small, allowing only the passage of the tractor and the accompanying orchard machines. The height of the lanes can reach 5-6 m. Not close to the rows, neither the high height of the lane walls creates an obstacle to good sunlight for the trees. The large fruit-bearing area of trees and good sunlight create conditions for very high yields, shortly after planting the orchard.
In conditions of poor sunlight of Central and Western Europe, the rows of lane trees must be low and at great distances from each other, so that adjacent walls do not shade each other. Hence, the yields are correspondingly lower. The lined forms are not as appreciated here as in the south of Europe.