Information

Extension rooting cuttings fruit tree

Extension rooting cuttings fruit tree



We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

Extension rooting cuttings fruit tree-growers in Southern and Eastern Australia need to know which dormant storage root to harvest from before

How can I be sure if I have a good stock of cuttings for a fruit tree? How long is their dormancy before the shoot tips becomes active again? What would be the best cuttings to plant in a new area and can they be safely buried in the ground? How can I tell if a root is edible?

Dormancy

In general, the active vegetative period of fruit tree stock is after a summer growing season when cold temperatures have been experienced (Figure 1). If no cold occurred, the onset of spring determines vegetative growth. Dormancy in this context is a period where the shoots/stems are not being actively grown (active vegetative growth). The dormancy period is broken by conditions which allow for shoot growth to occur. Dormancy in dormant stock is broken by budburst.

At the end of dormancy, shoot growth ceases but root growth continues. During this stage the rootstock may appear to be dormant in that the root stocks do not show any evidence of growth. However, once the temperature returns to suitable growing conditions, (susceptible stock), the dormant stock will break dormancy as growth will resume.

Factors in determining dormancy include: average summer temperature, cold tolerance and the degree of cold protection. Temperatures below 8°C will break dormancy.

Cold tolerance refers to the temperature at which leaves are damaged or killed. As a rough guide, the 20-year average maximum temperatures of a growing season in the north of New South Wales, Australia, can be described as cold or temperate, while those of a growing season in other parts of Australia, and the Southern Hemisphere can be described as warm (Table 1). Table 1 also shows that fruit trees in NSW generally tolerate a 5-year maximum summer temperature of 30°C or 35°C and winter temperatures of 10°C.

Figure 1. The Active vegetative growth cycle for plum.

(Source: http://www.nsw.gov.au/climate/crops/ac120410.pdf)

Table 1. Cold tolerance for fruit trees in the north of NSW, based on maximum winter and summer temperatures (Source: http://www.geelong.vic.gov.au/icd.asp).

Common Aborigines in the south-east and south-west of Australia don t experience any major temperature extremes during a growing season and would therefore likely be considered warm.

The same factors which determine whether a stock is cold-tolerant or not (cold tolerance) also determine the length of dormancy of the stock. A stock which is very cold-tolerant will become active very quickly, whereas a stock which is very susceptible will remain dormant for a very long time. The length of dormancy can be estimated by considering how susceptible the stock is to the average summer temperature. A stock which is very cold-tolerant would be able to grow actively under an average temperature of 8°C. A stock which is very susceptible to the average summer temperature of 8°C would have to experience 15°C temperatures to break dormancy.

Mulberry, chestnut, quince, sweet cherry and pear trees have been shown to be susceptible to freezing temperatures during dormancy and in the case of mulberry and chestnut they will actually produce very tender wood which is very susceptible to damage by cold. Pear trees are very cold tolerant but even these trees will display some tender growth around mid winter. The apple has been shown to be the most cold tolerant fruit tree species.

Warm autumn days are important in the growth of fruit tree stocks. Although warm autumn days will improve the growth of a stock, temperatures in the late autumn can be a limiting factor, especially in the south of NSW.

Rootstocks

The plant is the most important part of any fruit tree and because of this a good plant should have a healthy root system. For a small orchard, the root system can be an asset to plant stock. A root system will generally have its thickest section in the first 10-20cm of soil. Above this point the roots will be thin and of little value. If you can harvest roots from the bottom of an established stock, and use the fresh root system, then the root system should be as healthy as possible.

The life span of the rootstock is generally a maximum of 15-20 years. Rootstocks that are planted as young plants may live longer, but their life span has not been proven. Older rootstocks will have a much shorter life span and need to be replaced annually.

In general, there are three main categories of rootstocks used in orchard establishment:

open-pollinated varieties - the only breeding material available are clonally propagated from this plant (rootstocks for grafting)

hybrid varieties - will generally have two parents and can be used as a foundation for breeding and grafting. If the parent plant is still alive, the hybrid variety will often come from the same parent as the open-pollinated variety. Many of these varieties are used commercially

true species - the vast majority of true species orchards are used for grafting and breeding.

It is important to note that a variety of apple has never existed and that no apple can be propagated without sexual reproduction. Most rootstocks used today are clones of a single orchard, although this single orchard may be grafted onto as many as five or six different rootstocks.

There is now growing concern that open-pollinated varieties are being replaced with newer hybrid rootstocks that have the potential to produce improved fruit. In general, the hybrid varieties will not produce very well in the early season.

Cuttings

There are two main ways to obtain orchard trees: from seed or cuttings. Cuttings can be collected in the winter and planted in the spring. Alternatively, cuttings can be collected in the summer and rooted before planting in the spring. With cuttings, both the summer and winter growth on the plant is