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Peony
Developing an optimal propagation
Developing an optimal propagation 
Dr. Michael Robinson.
Arik Orlov Bs.c. – "Megical Peony" Nursery

Introduction:
The Peony(Paeonia lactiflora) is a plurienniel geophyte. It's subterrenial organ is composed by roots and it called "crown". The life cycle of the Peony resembles that of many decidual trees: In the spring the Peony flowers. Till autumn the canopy remains green, producing assimilates by photo synthesis, sending them downwards to the crown. During the summer the subterrenial new buds grow on the crown and in them the new flowers develop. In autumn, the canopy dessicates and the plant enter into dormancy. Accumulation of a certain sum of low temperatures during the winter breaks dormancy and in spring the wakened buds grow into long stems bearing leaves, on the head of the stem there is a flower.
Vegetative propagation:
There are several methods for vegetative propagation of Peony:
1)Tissue culture: Using this method, it could be possible to obtain a great quantity of small plants-plantlets in a short time. A considerable amount of research was made in the last years, trying to propagate Peony using this method, but with no success.
2) Rooting cuttings:
The cuttings are made from stem segments. Using this method, it could be possible to obtain a great number of rooted cuttings from one mother plant. In the base of the rooted cutting, the new crown should develop.
A good percentage of rooting was obtained, but almost no crown developed in the base of the rooted cuttings.
3) Crown divisions: This is the usual way for vegetative propagation of Peony. The Peony is grown commercially for the production of cut flowers. When there is a need for propagated material, the grower takes the old crowns out of the soil, divides each crown into several parts and sells those parts to other growers, or plant them for himself in a new area. The division of the crowns takes place in autumn or winter.
In this case, the main product is cut flowers, the propagation being only a by product. In this mode of propagation, the rate of propagation is slow and the quality of the propagated material is poor.
An alternative, intensive technique of propagation by successive crown divisions was developed recently in Israel:
The "propagated unit" is a fragment of a crown bearing some buds. Usually those units are defined as "2-3 buds" or "3-5 buds" and their price is determined by the number of buds per unit (and, of course-the variety of the Peony). Those fragments of the crown bear buds of several dimensions –
Now we had to define "The rate of propagation".
It is:" The number of the buds on a propagated unit in a certain winter (e.g. January 2008) divides by the number of buds in the precedent winter (jan.2007).
The basic principals of this intensive method of propagation are:
1) Young tissues: only the youngest parts of the crown (externals) are taken for the propagation. Using older parts results in many rotten crowns.
2) Small units: small segments of crown bearing only few buds serve for propagation. The marginal propagated rate is decreasing as far as the crown gets bigger and bears more buds. But, experience shows that if those units are too small they will rotten as well. So, in practice, those units should have at least 50 grams of weight.
3) Soil less cultivation: The crown segments are grown in small containers filled with growing substrate (tuff, perlite or other) the fertigation should be very accurate.
The procedure of the propagation is as follows:
During the months of november-december, the most younger (external) parts of the crown are separated from it by means of a sharp knife or another sharp device :

Considering the geometry of the crown, those segments should preferably bear only one bud (even one bud of the smallest type -"pin head") and so having small dimensions and light weight. Those small segments are disinfected and planted in small bags having 1-2 litres of perlite, or a mixture of 2:1 scoria: peat. Those bags are put in airy boxes in order to have perfect drainage .In Israel, the nursery is covered with 30% shade net.
In order to get good propagtion rate, the fertigation should be precise. It is done by continuous control of the water regime and the state of the chemicals in the growing substrate.
In the next spring, after the plants had already developed their whole canopy:


the grower classifies them: In the next autumn after the dessicassion of the canopy, the well developed ones will be sold and the less developed ones will be subjected to another division as described above.
With good performance of this technique, propagation rates of 2.5-3.0 are achieved. For example: Starting from a segment bearing 1 standard bud ( and 2-3 smaller buds), after 2 years of propagation( 2 successive divisions) , we shall have 2 plants bearing 3 standard buds each,( for sell) and one smaller plant bearing 1 standard bud (and some smaller buds) for successive division.

After 1 year – plant that had only 1 little bud and now has 3 standard buds :




Summery:
Advantages – 1. faster propagation.
2. less soil diseases(substrates).
3. no soil insects, like nematodes.
4. no need in "coocking disinfection" when sending to
other countries.
5. live roots(suckers) – better enrooting in the soil and
Better chance to have flower in the first year (and so to
find mistakes in the variety faster.


Disadvantages – 1. The crown itself is a little smaller.
2. The grower in the nursery should be very précised.
3. Much higher investment in pots, substrates, drippers
atc.


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