Supply of medicinal plant drugs is recently based on two sources, collection from wild habitats and production from agrar-ecosystems. Sometimes both of them are existing for the same drug (e.g. Altheae folium, Hyperici herba, etc.). The possibilities are changing during the time: wild growing plants are often drawn into the agriculture, but sometimes cultivated populations become also wild.

Introduction of plants into agriculture is one of the most ancient activity of humans, however in case of medicinal and aromatic plants it became widely known only from the beginning of the twentieth century.

Recently, introduction of medicinal plants is a common feature in the developed countries, which can be traced back to several reasons.

• Due to the up-to date scientific results, more and more active ingredients are described in the plants, moreover their therapeutic effects proved or newly recognized. Only in Germany, 50% of the medicinal preparations has a plant base and plant drugs of 1543 species are in the wholesale trade in this country (Franke, 1999). The growing demand of the raw can not be assured by collection of wild populations. Even, if the produced quantity of the natural populations would be enough for the supply, an over-exhaustion of the populations results in continuous decrease of wild stuck. Cultivation of selected material among controlled conditions is the only solution in these cases. Characteristic examples from the practice are Claviceps purpurea drawn into culture in the 30ies (Németh, 1998), Oenothera species introduced in the eighties (Anonymous, 1993) or Solidago virgaurea being under introduction today (Bohr and Plescher, 1997). As one of the latest cases, the enormous increase in demand - above 6000 tonnes pro year (Franke, 1999) - of Hyperici herba in the last decade necessitated an intensive introduction of populations of St. John 's Wort.

• Assuring standard quality of products is a basic requirement both in marketing of drugs and spices as well as in processing of phytopharmaceuticals, plant based medicines and other products. Natural populations are mostly diverse not only concerning their morphological features but also from point of view of their active ingredients. According to the Good Agricultural Practice (Franz and Máthé, 1997) standard quality can only be assured by producing known biological material by controlled methods. Thus, solution is introduction. The best known practical example for it may be chamomile, where legislated cultivars give the desired chemical compounds in the contrary to natural stands, whose active compounds are mixed or of uncertain level. In some cases, cultivated populations might assure also a desirable quality free of unwanted or harmful compounds. It would happen in case of cultivated horsetail (Equisetum arvense) while palustrin alkaloid might cause problems in wild growing materials. As another example, Chelidonium majus is a species often grown on dunghill or similar places where abundant nitrogen is present. The collected material therefore frequently shows an over-accumulation of pesticides or microbiological contamination which may be prevented by controlled cultivation (Bohr, 1997).

• Recently, more and more species became endangered or protected soon in consequence of tightening of their area and decrease of their populations due to general industrialization, pollution, or even exhausting collection for different purposes. Natural stands are not available any more to regenerate and serve as sources of plant raw in these cases. Beside the "passive" preservation and official protection, an "active" method for assuring the supply is cultivation. Arnica montana or Adonis vernalis are the best examples for it from the temperate zone (Bomme, 1999; Neumayer, 1997).

• Very often, a continuous and considerable demand for drugs is observable, from plants which are not indigenous in the consumer country. More and more, uncontrolled quality of drugs from developing countries or high transportation costs result in the decrease of import and may support the home production even of these plants. In several cases the biological and ecological requirements can be fulfilled, the plants grow and develop well, and they give economic yields. Thus, in the last decades the European cultivation of Echinacea species (originating from America), large scale production of Silybum marianum (coming from the Mediterranean) has been solved (Franke et al., 1997; Stieber, 1973). As result of successful research and development, Ginkgo biloba has been introduced into other countries and about 6000 tons of leafs are produced beside its Chinese home region, also in France and the U.S. (Shan-An et al., 1999).

• Beside natural, biological ones, social problems may threat collection of medicinal plants too. In Europe, South-East counties mean the most significant sources for the drug supply. In these countries, as a new phenomenon after the political changes in the 90'ies, privatization of fields, meadows and forests resulted in prohibition or restriction of collection (Bernáth, 1999). Besides, people are less capable of this tiring work as collection of plants or parts of plants which does not always pay properly. The lack in free growing areas and labor may lead to the need of introduction of certain species. That is why - although they are yet fully collected plants - hawthorn, elder or linden may be the topic of introduction in the coming days (Bohr, 1997).

• In the developed countries, agriculture produces surplus of traditional crops and is to be restricted. Council Regulation EEC 1765/92 and its updates establish a support system for producers of certain arable crops. Although cereal areas must be reduced, it is permissible to use the set-aside lands for "non-food" crops, including medicinal plants. Farmers compiling this regulation are compensated by the EU (Lange, 1998). It means, that among different plant cultures medicinal plants and spices belong to the category, which is not restricted but supported. Species, which were formerly wild growing, seem to be able to assure proper income for farmers cultivating them.

Introduction of plants into the agriculture is a time consuming process even in our days. Possessing the up-to date technologies, 5-10 years seem to be necessary for solving the problems of cultivation in the practice and developing an accurate production system. It presumes the knowledge on the basic production-biological information of the species. Therefore, strategy of introduction includes careful investigations on the eco-physiology, genetics, chemical features as well as production potential of the chosen population. Founded by experimental results, a cultivation model can be built up, which is further modified according to production trials.

In the following, the most important theoretical or practical problems during introduction are summarized.

Wild growing populations are heterogeneous both from point of view of their morpho-phenological properties as well as from the chemical side. According to Franke (1999) introduction is a process, during which even today culture-species are developing from the wild growing ones. It is a long-term process, but can be speed up by appropriate selection. For the economic cultivation, the most important plant characteristics are the yield determining ones, both from quantitative as well as qualitative point of view. Growth form, proportion of organs, tolerance against abiotic and biotic factors, development of viable propagation organs and content or composition of effective material in the utilized plant part are the most often emphasized features as topics of breeding work, although individual specialties may happen depending on species (Table 1).

Information on the genetic structure of these populations is scarce. Knowledge on the phenotypical variability and on marker traits between chemical and other characteristic could speed up selection and improve the efficacy, but they are also rarely described. This lacking knowlegde on the biological background and the original heterogeneity allows selection - mass or individual - being the most often used method of breeding during introduction. As a usual method, different origins are collected and examined in detail for morphological, chemical and production characteristics, followed by improvement. According to Plescher (in Pank, 1999) the selection work is one of the most expensive task during introduction which can not be solved without participation of the interested firms.

The results of breeding work carried out for introduction are several new varieties, such as the German 'Arbo' for Arnica montana, 'Delikatess' for Taraxacum officinale, the Polish 'Cynober' for Chelidonium majus, the Swiss 'Petzell' for Petasites hybridus or the Hungarian "Napfény" for Verbascum phlomoides (Pank and Heine, 1998).

Genetics is the basis of optimized production, but it will be realized in the growing environment, under the influence of different ecological factors.

In case of the indigenous, wild growing species, natural occurrence may assure information on the requirement of the species. However, it does not directly mean, that the presence of a population always indicate the optimal growing area of that species. In general, species of wide ecological tolerance may potentially give high and stable yields in the agriculture, however it needs species-specific optimization.

Soil is a basic element of cultivation. Its nutrients effect the primary production (biomass), secondary metabolites and their yield, condition of plantation and length of its life. Nutrient requirement is usually determined by measuring the quantities utilized from the soil by plant analysis. In our cultivation trials, fertilization with 80 kg/ha nitrogen resulted in 18% increase of leaf mass in the average of four Urtica dioica populations (unpublished results). Besides, several other physical and chemical properties contribute to the effect of soil and use of nutrients, such as porosity, content of lime, pH, thickness of fertile layer, etc. In Europe, soil pH proved to be a limiting factor during introduction of Arnica montana or Gentiana lutea, which could be solved only selective breeding of resistant cultivars (Hostettman, 1994) and choosing the proper growing area (Bomme, 1999).

Precipitation is in tight connection with the soil type. It may highly determine yield of the plants, accumulation of effective materials, ripening of shoots and seeds. The effect of water supply is partly indirect, influencing the chemical properties through the proportion of the organs or regeneration ability during the vegetation period. In experimental cultivation of Tanacetum vulgare, the population assured 1.64 times higher fresh mass compared to the control, with application of 2 times 40 mm irrigation. The yield increase showed an interaction also with the genotype of clone (Dobos et al, 1992). In the course of investigations the optimal level of irrigation and economy of production should be determined.

Temperature is a complex factor, which acts through its absolute (eventual minimum or maximum) values and also through the heat-sum received by the plants. The problems arise especially during introduction from other geographical regions. In the majority of European areas where introduction had been carried out recently, minimal temperature values caused severe problems restricting overwintering of culture such as fennel, rosemary, majoran. It is known that low winter temperature connected with lack of snow, furthermore a wet autumn period hindering shoot ripening may contribute to frost damage. However, in several cases flexible solutions are possible. Foeniculum vulgare can be cultivated in its home region in Italy during 4-5 years, in Hungary only 2-3 years and further to the north in Germany, most often only an annual culture is possible (Dachler and Pelzmann, 1999). Weather conditions, especially temperature are a basic factor both in growth and in the accumulation level of active compounds. As it is demonstrated by the example of Vinca minor by Márk et al. (1969), the vincamin yield was affected by weather conditions, a positive correlation was determined between vincamin content and temperature as well as duration of sunshine.

In the lack of necessary heat sum plants fail to blossom or to produce seeds. During introduction of several spices into Finland, it turned out, that the sum of heat will never reach the appropriate values to produce flowering marjoram, savory or ripen annual caraway fruits, although maximum summer temperatures may reach the Hungarian ones in the southern areas (Galambosi, 1996). An over-accumulation of heat during the vegetation period may similarly arise problems. In the eighties, introduction of Siberian genotypes of Hippophae rhamnoides was carried out into Hungary. The relatively early beginning of vegetation in spring and high temperatures in summer resulted in two months earlier ripening of the berries, than at home areas of the species. In consequence, harvesting - which was traditionally made by beating down the berries after the frosts - caused severe difficulties (Bernáth and Földesi, 1993).

Light is in general a prerequisite of plant life. In case of successful introduction, two aspects should be taken into consideration: strength and length of illumination. The first one proved to be a problem during introduction of forest species into open filed conditions. In plants which live in shadow or semi-shadow conditions, direct sunshine causes burns, reduced growth, sterile flowers and perishing. Cultivation of Vinca minor had been stopped in Hungary after some years of intensive research in the 70ies, because open field conditions made this undergrowth species extraordinary sensitive for different diseases and the production uneconomical. Commercial production of Panax species is only possible under proper shading equipment (Roberts, 1979).

The length of illumination effects first of all species from far-away areas, which have a different photoperiodical behavior than our indigenous species. Without taking this problem into consideration, the whole success of production might be cancelled. Flowering induction, fruit development will fail, the chemical composition of the drug might change (Németh et al., 1993).

Agrotechnical methods should be effective, economical, species-specific, up-to-date and reproducible. Elaboration of different agrotechnical steps should be carried out parallel with each other, with study of ecological requirements and with selection work.

Propagation is in many cases the first and most difficult task. Wild growing species are used to produce seeds germinating unregularly in order to assure long term existence of the population. They are characterized by a low and fluctuating germination capacity (Neumayer, 1997). However, in cultivation an even and quick germination or sprouting seems to be necessary. This aim can be reached by breeding as it is demonstrated on the example of poppy (Figure 1.) or may be solved by appropriate seed-treatments. As the ecological conditions of the production year, furthermore the storage time, ripening status etc. each may influence seed germination (Tóth, 1999), for successful propagation knowledge on the seed-biological properties is necessary.

Figure 1. Germination of Papaver somniferum seeds of different origin after harvesting and during
the next 36 months (Tóth, 1999)

In many cases the alternative propagation by vegetative organs assure more success. Using the best plant organ at the right period may influence not only taking root but also the future yields, as it was proved with Symphytum officinale root particles. Planting with roots containing root-stock parts produced three-times higher in the first and about 15% more root yields in the second year (unpublished result). The lack of proper and effective propagation material may be a severe obstacle of the whole cultivation. In Equisetum arvense germination of spores and sprouting out of rhizomes, in Adonis vernalis the exact period of collecting and sowing the seeds are subjects of long time trials in different countries, however, propagation and therefore cultivation is still unsolved.

Care of plants includes eventual nutrient supply, irrigation, weed control, plant protection or special tasks. Each of them are important ones, considering, that treatments at the right time may save the crop at certain circumstances. The behavior of the introduced plants may considerably differ from the original ones living under natural circumstances concerning their competition ability and resistance against pests and abiotic factors. There are several examples from the practice of the last decades, where unexpected plant sanitary problems arised from the changed life circumstances of the population. Beside the mentioned example of Vinca minor, the insect damage (Hemimene petiverella) of Achillea collina or the perishment caused by fungi (mainly Colletotricum spp.) of Hypericum perforatum can be mentioned (Petzoldt, 1991; Gäber, 1999). Big stands were destroyed by this complex disease thorough the world, which necessitated complex research and elaboration of protection methods as well as creation of resistant strains (Gäber, 1999).

Weed control proved to be a basic problem, especially in perennial cultures. It needs careful experimental investigations in case of each species. It should be made parallel with elaboration of propagation and harvesting technologies, connecting with crop sequence. Today, integrated methods are to be preferred preventing pesticide load but preserving the active materials at the same time.

Harvesting should be optimized in order of getting the desired drug of desired quality as well as getting an economical yield. Starting point may be the collection method and time from the wild habitats, however, yields of the biomass and effective materials may be different and are the topic of optimalization. As selected materials in cultivated stands may have more intensive growth and development and production potential than wild origins, mechanization and possibilities of repeated harvest during the years should also be investigated. While wild growing Tanacetum vulgare L. is traditionally cut once a year at full flowering, in cultivation it gives highest yields when cutting the 30-40 cm long vegetative shoots twice a year or harvesting the flowering shoots followed by cutting of the new sprouts in autumn (Németh et al., 1994). Detailed production-biological investigations reveled that harvesting the flowering tips of St. John's Worth would give higher hypericin yield than cutting the whole flowering shoots as is the traditional method (Bomme, 1997).

Both, the material from collection of wild growing stands as well as from harvest of the cultivated ones need post harvest processing (drying, cleaning, chopping, extraction, etc.). This step might be almost similar for the two kind of raw depending basically on the type of the drug, however quantities are mostly different. As there are usually small charges in case of collection, much more higher quantities needs processing in cultivation. This difference necessitates changing methods, another type or scale of equipment.

Introduction is a stepwise process based of information on biology and ecological requirements of the species, using similarities with other, traditionally cultivated plants, needs experimental investigations as well as effective cooperation with scientific institutions (Franke, 1999). Such kind of investigations resulted in significant numerous practical achievements in the last several decades (Table 2.). As one of the earliest one, introduction of ergot can be mentioned which resulted in a multiplication of alkaloid yield for the pharmaceutical processing (Németh, 1998). Among the latest and most important results the solution of the successful cultivation of Pacific yew (Taxus brevifolia) is to be emphasized. A complex system of selection, maintenance of cultivars, propagation in vivo and in vitro, production at intensive large scale fields in 3-5 years crop rotation, harvesting and extraction of needles and shoots assures the growing demand for the raw of anticancer medicines. Today the living stucks in the U.S. provide a long-term reliable and economic source of pachitaxel (Piesch and Wheeler, 1993).

The Resolutions of II World Congress of Medicinal and Aromatic Plants (WOCMAP) in Mendoza emphasized the importance of taking species into the culture and elaboration of up-to date technologies (Van der Borg, 1999). Presumably more and more species are going into the culture in the forthcoming period (Table 3.). Learning and conclusions from the results of the past may assure a suitable basis for the coming achievements.

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