Cut Rose Cultivation Manual - ROSE PROPAGATION
Current and existent propagation methods are cutting and stentling which are used on 75% of the plantlets by specialized companies worldwide.
One of the most important and delicate phases of the roses productive process is propagation. There are many different methods of vegetative multiplication which is synonymous with propagation of the rose. The choice of method of propagation of the plantlet depends upon various factors.
• The growers financial position (i.e. a grower can decide to propagate by himself, however paying the patent to the breeder company or owner)
• The type of greenhouse and the type of technology available on site in the nursery.
• The choice being made as to whether the rose is to be cultivated soil less or on soil.
• The planting period.
30 to 40 years ago, more and varied propagation methods were used as opposed to these days.
Current and existent propagation methods are cutting and Stentling which are used on 75% of the plantlets by specialized companies worldwide.
Dormant-eyes grafting is most commonly used in Asian countries; South American countries namely: Mexico, Colombia, Ecuador, Uzbekistan, Kyrgyzstan and in some European countries namely Poland, Spain, Italy, France) as an auto propagation method.
The propagation methods which have almost disappeared altogether or exist only in marginal cultivation areas are techniques such as bench grafting, root grafting and winter grafting. The disappearance of these latter methods as being widely used is because of the larger consumer needs, which require greater production and a more efficient method of marketing and air transportation, as well as the need to produce flowers and plantlets of a superior quality.
Added to that, bench grafting, root grafting and winter grafting are maladaptive to the latest technology, improved professionalism, and modern greenhouse production required by the current sophisticated market demands for flowers.
Bearing the above in mind, regarding the more sophisticated and increased market demands; the type of recommended plantlet should be as follows:-
• A plantlet which is unaffected by disease;
• The plantlet should be certified quality;
• Plantlet of same age and quality;
• The plantlets should have their original five leaflet leaves and be in a good vegetative and sanitary state;
• The root system must be homogenous, white, visible and well developed at the base of the plug.
It is important to emphasise that although the above requirements appear simple, the importance that they be adhered to cannot be over emphasised because the rose plantlets must have these qualities in order that the advanced structures and technology and the highly qualified personnel producing the flowers are not compromised by unsuitable plantlets, being introduced in a large nursery where they can spread disease.
The risk of having plantlets with e.g. agro-bacterium, viruses etc., usually depends upon the professional approach of that rose production nursery and the structures in place as well as the hygiene that will be used. However, it is stressed that among the 95-98% of global rose production, the propagation methods used are without a doubt, cutting, Stentling and dormant eyes-grafting.
HOLLAND (Schreurs) - CUTTINGS
The latter can be done as follows:
Grafting on one year bushy outdoor plants, (i.e. when done on root stock plants grown (or rooted) from seed outdoors); or
Grafting on rooted greenhouse rootstock, (i.e. when the graft is made on wild plantlets (root stock) in the greenhouse); or
Grafting on un-rooted indoor rootstock (i.e. when the graft is done on wild un-rooted rootstock segments either in the laboratory or working area).
This kind of propagation technique has become the most commonly used thanks to the improvement of:
• Greenhouse structures being used with techniques in soil-less cultivations;
• The efficiency of the new synthetic root hormones;
• The variety of genetically improved roses that give maximum and prolific productivity in climate controlled greenhouses.
Another advantage which stems from the method of cutting plants is that they are available all year round. In fact, in Holland, research has concluded that 95% of varieties propagated through cutting have resulted in being the most productive.
Against that backdrop, grafting on Rosa Inermis via Stentling has resulted in less productivity.
Grafting on the Rosa N. Briar which is always via Stentling, (on a certain number of varieties) has actually resulted in an improvement of more stem length.
Because of increased productivity through the cutting method, the cutting method has become most popular to the extent that it is no surprise that 70% of Hollands growers prefer cutting plants instead of grafted plants (via Stentling). Cuttings are also cheaper and are widely used for worldwide demand, because the time which elapses between cultivation and production has been significantly decreased.
Further to this as an added bonus, the following spring re-shoot does not lose the variety but conserves it. The only risk to re-shooting would be the unfortunate scenario of the plants freezing from poorly heated environments.
Rose propagation via cutting begins with collection of the budwood of the variety that has been chosen for propagation. The roses are cut into little segments, each of which has at its extremity, a simple five-leaflet leaf.
Selecting the ideal budwood.
It is emphasised again that the budwood should be healthy, clean, strong and unaffected by any disease. When choosing the budwood, the producer must avoid using budwood that is too tender (which suggests that it has few reserves). In addition, budwood with auxiliary buds (eyes) which are beginning to look swollen or are actually starting to shoot must be avoided. The ideal budwood on the other hand will have dormant or only slightly swollen auxiliary buds. From the ideally selected budwood which has dormant buds, the petals colour (or flower) can be examined and therefore determined.
Processing the budwood.
The first thing to do to the selected budwood is to remove the basal extremity and the distal. Therefore the budwood should be cut 15 cm from its base to remove the basal extremity while from the distal portion, the last three leaves, (usually made up of less than five-leaflets) from those which have open or swollen auxiliary buds are eliminated.
The reason for removing the base portion is that often the leaves are too small and when they are too small it means that insufficient photosynthesis has occurred for the auxiliary buds that should shoot. Another important reason for cutting off the base portion is that there is an increased risk of the Agro-bacterium or other viruses being present in the budwood. Risk of contamination is therefore removed by cutting the base portion.
Cutting the budwood into segments and preparation for transplantation. The budwood is usually divided into 3-5 small Cuttings of 6-8 cm each with a five-leaflet leaf at the extremity. The Cuttings are then placed in plastic containers and temporarily put into a refrigerator.
Before transplanting the Cuttings on the medium (or grafting them), renowned companies completely immerse the Cuttings in a disinfectant or anti parasite solution. The procedure which has just been described is identical to the first phase of Stentling, the only difference in this procedure being that the Cuttings are generally cut shorter.
Meanwhile, the plantlets are immersed at the base a few centimetres into a solution containing rooting hormones. Thereafter, the plantlets are taken into a special rooting environment and undergo four phases.
In the 4th phase, otherwise known as the hardening phase, (in order to strengthen and adapt the plantlets to less hard conditions) propagation companies create climactic conditions, similar to the climactic environment of a cultivation greenhouse.
During all first three phases, no CO2 is added to the plantlet, because the stomata are practically closed due to the very high Relative Humidity. Use of CO2 then is therefore ineffectual and expensive. Only in the last phase (4th) when the greenhouse is open, do the plantlets begin to use CO2 in the air with values of about 330-340 ppm.
The total duration of the phases is 4 to 5 weeks on average. However, plantlets which are propagated via Stentling, and in which the phases and climate are similar, only the last phase is an additional 5 to 6 days.
In African and South American countries, Japan and South Korea, the time between the various phases and the total days to create a plantlet vary, as they are influenced by the outside climate. Especially when the climatic parameters are not always kept under control. Considering varying night/day temperatures; the absence of artificial light and, at times, inefficient fog-humidification system (which wets the plantlets) and poor hygienic conditions, will result in the plantlets often being weak, diseased and insufficiently rooted.
In countries like China, Vietnam, Thailand, Taiwan and Brazil the method of propagation via cutting is used by 90-95% of companies. In Vietnam and Thailand 90-95% of Cuttings are done outdoors, the other 5-10% being done in a greenhouse on soil. This is because of economic reasons, poor propagation structures, limited expertise, and limited knowledge of alternative propagation methods.
Most of the Cuttings are put to root in organic medium, such as peat moss, placed on wide beds. When they are ready, they are easily uprooted, cleaned out and then sold on markets or in neighbouring countries. In fact, Vietnam and Thailand growers buy about 60-70% of their cutting plants from nearby China. The rest of the cutting plants would be produced in their own territory. Only 2-3% is bought in Holland.
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Elimination of the basal portion
Elimination of the apical portion
The plantlets reproduced via stentling in Holland (Schreurs) are shorter than those produced in South American countries
Generally the plantlets with reddish leaves at the extremities of the plant, present a greater rooting
Budwood used for propagation