The history of this method is interesting. The first attempts to cultivate tissue parts and single cells in artificia environmentl (in vitro, "in tubes") date from the beginning of the twentieth century, when German scientists conducted laboratory experiments in that direction. Haberland- a famous зspecialist for Botany and plant Physiology, was the first to perform such attempts; even they werw not successful, he remains the first one who formulated quite clear the very idea of groing single plant cells in glass containers and on artificial culture medium. This is in fact, the first stage of birth of that important science. Typical of the 30's of the twentieth century are not practical success but the search for optimal conditions of planting, balanced nutritional solutions, proper methods for inducing growth, division and differentiation of plant cells and tissues, and also formulating the leading ideas, turned into foundation where the next development of this biological direction lays. After many attempts, in 1933 the French scientist Roger Gautret successfully cultivated parenchyma of roots, tubers and cambial tissues of woody plants on artificial nutritional medium. Merely in the same time the American Philip White successfully developed his method of cotinued in vitro оcultivation of root meristem of tomato plants. These two experiments mark the beginning of rapid development of the method of the tissue culture and, respectively, the two scientists are rightly considered to be its founders.
From the beginning of the 40's of the tentieth century to nowadays the method has been constantly improved. The technological advance of biology and biotechnology enables the full methodical and technological sustain of the experiments and makes possible their use as daily practice, which is the base of the continuing progress of the agricultural science.
The basic methods of getting tissue culture are developed on relatively few proper objects – petunia, tobacco, carrot, lucerne, and also on some wild plants. Certainly, the number of the plant species, included in experimental in vitro development, grows up significantly later. Nowadays are known and described methods of cultivation in artificial nutritional environment of more than 850 plant species. The experiments show that conditions, necessary for one certain species, are not always the same for the other, so for each species, and often for each variety, the basic methods need modifications. Otherwise, the experiments and the practical application in tissue culture walk hand in hand and many discoveries in this area are about to happen. Tissue culture are used as in the fundamental general biological research, and in selection in planting. The plant parts able to cultivate in vitro are: merystema, plant organs(еmbria, flower buds, семепъпки, завръзи, seeds, pollen, roots, leaves, stem parts), callus (able to introduce in each part of the plant and cells. Regarding the perspectives, related to using tissue culture in planting paulownia, the achievements in in planting and selection are extremely important.
Fundamentals of microreproduction
The basic technological points of the cycle of microreproduction are related to certain factors:
- variety and species' features of the reproducting plant
- сterm for taking the explantants
- sterilization of the source plant material
- composition of the medium
- conditions of planting
- adaptation of the microplants to the environment
It's extremely important to determine the exact term for taking the explantants according to the physiological features of the plant species. For paulownia introducing in sterile culture is during the active vegetation of the plant.
The surface sterilization of the plant material has vital importance for the whole process. If it's unsuccessful, the nutritional environment is contaminated, the whole process is suspended and the plants die. The type and concentration of disinfectant solutions are selected to suppress any kind of mycotic or bacterial infection remaining the plant tissue intact. Frequently used solutions are calcium or sodium hypochlorite in 5 - 25 % concentration for 5 to 30 minutes, followed by several rinses of the plant material with sterile distilled water. Certainly, it's possible to use other sterilizing solutions. For the successful microreproduction it's important what the composition of the nutritional medium is during each phase of the plant's development. The nutritional solutions have several different ingredients in different proportion (vitamins, оorganic supplements, carbohydrates, macro- and microsalts). Several nutritional solutions have been developed on which different solutions are modificated and prepared as the specific needs of the plants require. These are the solutions of Murashige and Skug, Gautret, White, Morel, Skirgin, Gamborg, Knopp.
During the first phase of the proccess there is amplified increase of the vegetation apex. At this stage, except the substances from above, the nutritional solution must contain also suitable growth regulators. Their concentration is essential, as their proportion. Still the rate of the explantants which are successfully adapted, not only depends on the balace of the nutritional solutions, but also on their size and the date of collecting them. During the phase of multiplication (amplified reproduction), is important to raise concentration of certain growth regulators to trigger proliferation of additional side buds. If the conditions are correct these buds originate shoots (little plants), which form tuft. How many shoots will be in a tuft depends on quantities of great importance – the propagating rate, which is different for each species. There are techniques to help to increase this rate. Generally, the purpose of this phase is reaching the necessary number of plants which allows the pass in the next phase - roothold.
Despite the techniques developed and multiple modifications at each stage of the micropropagation technology, one of the most difficult and responsible time in the whole cycle is the adaptation of the in vitro grown plants to the environmental conditions. Although the plants are removed from the culture vessels after formation of root and land parts of sufficient size and a number of leaves, ther is always a certain amount of weaker plants which die. Those which survive and adapt well, are not ready for implementation yet. It's necessary to be cultivated in greenhouses – different depending on seasons. They reach their final size there, which makes them fit for replanting, so practically they don't differ the traditionally made seed.
The exact knowledge of each step of the process of producing plants in vitro allows to plan each of the described phases. In the laboratory we have all the hygienic and technological requirements are complied for the proper functioning of the micropropagation. The proper organization and conditions allow programmed production so that from one single plant for 52 weeks we are able to receive not less than 200 000 new plants with qualities completely identical to the parent. Our constant concern is the seed to be aligned – all the plants to be at the same phase of development and to grow withequal intensity. The method of micropropagation of paulownia requires lots of capital, strict adherence to the statory requirements, expert knowledge of the technology and care to its constant improvement. It's not easy to do all this work but we are conviced that's the right way, because this method of paulownia propagation is 6 to 12 times faster than the traditional ones. Paulownia has large propagating rate - an advantage we can't ignore. The healthy, free of patogens seedlings we obtain, the reduction of the initial phase of plant development and multiple smaller space required are just some of the benefits we provide to our clients introducing this most - now modern method of vegetative propagation.
Currently Velboy Ltd. has seed of Paulownia elongata and Paulownia tomentosa. Recall that the expected turnaround time and delivery depends on the size and availability of your order. Please, order in time to have guarantee of timely delivery!
