Determinative ecological factors of growing site 1. Latitude, altitude (light and temperature conditions)

Latitude and altitude influence the intensity of solar radiation, hereby the light supply and temperature considerably. At different latitudes the incidence angle of solar radiation is different, it decreases from the Equator towards the Poles, so the same amount of radiation energy is distributed over a larger surface. Thus, the radiation energy and in this way the warming of Earth's surface is decreasing moving away from the Equator.

Altitude also affects light supply, because moving away from sea level the thinner atmosphere can transmit more and more solar radiation. But temperature decreases upwards, approximately 0.5°C per every 100 meters.

Hungary is located at the height of 46 and 48° latitude, but it is very varied in terms of temperature and light conditions because of its topography. The southern part of the Great Hungarian Plain is the sunniest (more than 2100 sunny hours/year), and the least amount of sunlight is experienced in the Hungarian part of the Alps (less than 1800 sunny hours/year). The highest temperatures are measured in the south-east part of the Great Plain, here in July the average temperature is more than 22°C, and the coldest areas are in the North Hungarian Mountains (the average temperature is 18°C in July). The pattern of heat sum values in the vegetation period is also similar (Figure 3.1.). In case of perennial or overwintering plant species the temperature conditions of winter are also very important (e.g. number of frost days, minimum temperature values, winter temperature fluctuations).

Figure 3.1. Heat sum of the vegetation period in Hungary

Because of this high meteorological heterogeneity both warm-demanding (e.g. Calendula officinalis, Chrysanthemum cinerariaefolium, Cucurbita pepo var. styriaca, Lavandula species, Majorana hortensis, Malva sylvestris subsp. mauritiana, Ocimum basilicum, Ruta graveolens, Salvia officinalis, Salvia sclarea, Satureja hortensis, Silybum marianum, Thymus vulgaris, Trigonella foenum-graecum) and moderately cold-demanding species (e.g. Angelica archangelica, Carum carvi var. biennis, Hyoscyamus niger, Hippophae rhamnoides, Humulus lupulus, Verbascum phlomoides) can be grown in Hungary. But we can cultivate them successfully in different parts of the country: warm-demanding species mainly in the southern parts (e.g. Tolna, Baranya, Bács-Kiskun, Csongrád, Békés county) while moderately cold-demanding ones in the northern regions. Winter poppy can be grown most safely in the north-west of Hungary, because the fluctuation of winter temperature there is the smallest, therefore the risk of frostbite is very low.

Since temperature and light supply are kind of environmental factors which can‟t be influenced by agrotechnical methods or only hardly (e.g. using of adequate planting space, cultivation of breeded varieties, active or passive frost protection, etc.), we should pay very much attention to them during growing site selection.

3.1.2.2. Topographic conditions

The exposure of the area, it‟s height relative to the environment, the slopes‟ steepness, the nearness of low-lying areas also influence the light and temperature conditions of growing place, hereby the living circumstances of cultivated plant species. In the northern hemisphere the south-facing slopes are warmer than the north-facing ones because of the greater incidence angle of solar radiation. Artemisia absinthium, Hyssopus officinalis, Salvia officinalis, Thymus spp., Lavandula officinalis like the south-facing, sunny, warm hillsides, because they are light- and heat-loving species. Thus it is no coincidence that lavender cultivation evolved in the region of Lake Balaton on the southern slopes of Tihany peninsula (Figure 3.2.). In case of some medicinal plant species (e.g. Chrysanthemum cinerariaefolium, Majorana hortensis, Pimpinella anisum, Rosmarinus officinalis) it is particularly important to select frost protected growing sites. At marigold cultivation the low-lying, humid places are very disadvantageous because the risk of powdery mildew infection is high under these circumstances.

Figure 3.2. Old, abandoned lavender plantation in Tihany 3.1.2.3. Amount and distribution of precipitation

Precipitation is one of the most important climatic elements of agricultural production, but its distribution is very variable both in space and in time. Water is indispensable in plants‟ life, although there are big differences between their needs. Angelica archangelica, Ocimum basilicum, Digitalis lanata, Echinacea purpurea, Humulus

lupulus, Calendula officinalis, Levisticum officinale, Valeriana officinalis, Cucurbita pepo var. styriaca, Majorana hortensis, Mentha x piperita, etc. are water-demanding species, while Cnicus benedictus, Hyssopus officinalis, Thymus vulgaris, Lavandula angustifolia, Salvia sclarea, Verbascum phlomoides, Chrisanthemum cinerariaefolium, Plantago lanceolata, etc. are drought-tolerant plants with lower water-demand.

The rainiest area in Hungary is the Hungarian part of the Alps (in the western part of the country), where the annual amount of precipitation is more than 800 mm. And the least rain falls in the central part of the Great Hungarian Plain (less than 500 mm/year) (Figure 3.3.). In Hungary otherwise the annual precipitation can‟t satisfy the plants‟ needs in general.

Figure 3.3. The annual amount of precipitation in Hungary

When we evaluate a growing site in terms of precipitation, we should allow for further aspects too, such as: precipitation during the vegetation period (which is usually 55-65% of the annual amount), rainfall intensity (mm/minute or mm/hour), number of rainy days, frequency of hail, frequency of precipitation-free periods, number of snowy days (it‟s very changeable: in the Great Plain 30-35 days, while in the North Hungarian Mountains 100 days), the first and last day of snowing, etc.

Thus during growing site selection precipitation conditions of the territory should be considered too.

Although this environmental factor can be slightly modified by agrotechnical methods (e.g. irrigation), they can be applied only in very reasonable cases and in relatively small areas because of their high cost. If we have to supply the missing amount of water with irrigation, it‟s important to have irrigation facilities and irrigation water in the selected area.

3.1.2.4. Prevailing wind direction, wind speed, frequency of gusts

Wind is a natural phenomenon, but too much of it can damage the soil (deflation) and the vegetation too.

Permanent strong winds can injure the foliage of plants, and the sand carried by wind can depose on the leaves of plants, clogging stomata. Wind also enhances the evaporation rate, furthermore dries the top layer of the soil.

In spring it may inhibit the development of young, delicate plantlets and at flowering it can hinder the activity of pollinating insects. Moreover, wind can carry away the small seeds from the loose, dry soil after sowing. Naturally

it has beneficial effects too, such as wind can offset the negative weather conditions; in spring March winds dry the too wet soil which is unsuitable for cultivation yet; it may facilitate the pollination and fertilization; as well as it can enrich the fertile layer of the soil with carried fine dust and loess. In Hungary the most frequent wind direction is the north-west (Figure 3.4.).

Figure 3.4. Wind map of Hungary

Taller-growing species (e.g. Malva sylvestris subsp. mauritiana, Silybum marianum, Verbascum phlomoides) usually require wind-protected areas, just like plants which scatter their seeds easily. In this case windy weather during ripening may cause considerable loss. In a windy growing site we can defend against wind with planting hedgerows or forest belts or with setting-up fences and wind break meshes around the territory. On the other hand, we can utilize the advantageous effects of wind, for example in plant protection. If we produce rows parallel with the prevailing wind direction in the course of marjoram sowing, wind will stop the warm, humid microclimate within the population. This way the probability of alternaria infections can be reduced.

3.1.2.5. Soil conditions

Soil conditions, such as type and structure of the soil, its pH, nutrient and lime content, the thickness and homogeneity of fertile layer, the level and fluctuation of ground-water, the soil‟s water-holding capacity and water permeability, the soil‟s contamination by pests and pathogens, etc. are also very important aspects during growing site selection. Plants should be cultivated in a kind of soil which can satisfy their biological needs completely. And although some soil properties (e.g. structure of the soil, pH, and nutrient content) can be improved significantly by agrotechnical methods, others can hardly be modified or not at all (e.g. thickness of fertile layer).

The most important soil types (in Hungary):

 brown forest soil: it is found in the mountains and hilly areas under cool and wet climate. It has many types, but each of them is brown coloured, has calcium deficiency and high clay content. Generally more difficult to cultivate them, because the fertile layer is thin and the territory is often sloping, stony.

 chernozem soil: it is formed on loessy lowland areas under drier climate. It is a good-quality soil type, which can be characterized by thick fertile layer. It is medium heavy and rich in nutrients.

 sandy soil: it has loose structure; therefore it is prone to deflation. Sandy soils‟ water permeability is good, but their water-holding capacity is weak. The lower organic material content is typical of this soil type. However, its advantage is that it can warm up easily and animal pests can live in it only with difficulties.

 saline soil: it contains an excess of water-soluble salts, especially sodium. Salts are found partly dissolved in the soil solution, partly bound on the surface of soil colloids or as crystalline salts. Saline soils are very heavy, their water receiving capacity and water permeability are very weak but their water-holding and nutrient supply capacity are very good. These are suitable for only a few plant species‟ cultivation (e.g. chamomile).

 humic gley soil: the periodically too much wet played a significant role in their formation. This kind of soils are very heavy and clayey, it is very difficult to cultivate them. Their humic substances are grey or black coloured and sticky. Nutrients, especially phosphorus and nitrogen are bound strongly in them. Their water receiving capacity and water permeability is weak, but their water-holding capacity is very good.

At growing site selection the pH of soil should be also considered, because this is a kind of feature, which can‟t be influenced significantly in large areas by agrotechnical methods. Many plant species are undemanding in terms of soil‟s pH (e.g. Angelica archangelica, Mentha x piperita, Achillea collina, Sinapis alba, Anethum graveolens, Humulus lupulus, Calendula officinalis, Levisticum officinale, Carthamus tinctorius, Oenothera erythrosepala), but there are demanding species too. Vaccinium myrtillus, Castanea sativa, Arnica montana can survive only in strongly acid soils, while Melissa officinalis, Hippophae rhamnoides, Hyssopus officinalis, Matricaria recutita, Echinacea purpurea, Lavandula angustifolia, Valeriana officinalis, Althaea officinalis, Verbascum phlomoides, etc. are fond of alkaline soils.

The nutrient content and nutrient supply capacity of soil are also important characteristics, but these can be modified significantly by natural (e.g. green manuring, organic fertilization) or artificial (application of chemical fertilizers) methods. Nutrient-demanding species: e.g. Angelica archangelica, Hyoscyamus niger, Mentha x piperita, Levisticum officinale, Leuzea carthamoides, Cucurbita pepo var. styriaca, Ruta graveolens. Low demanding ones: Cnicus benedictus, Achillea collina, Sinapis alba, Trigonella foenum-graecum, Hippophae rhamnoides, Hyssopus officinalis, Matricaria recutita, Oenothera erythrosepala, Silybum marianum, Verbascum phlomoides, Chrysanthemum cinerariaefolium, etc.

The soil‟s contamination by pests or pathogens should also be examined before planting, especially if we would like to cultivate perennial plant species. For example peppermint is very sensitive to the injury of wireworms (Limonus spp.), root-knot nematode (Meloidogyne hapla), crane-fly (Tipula spp.) or cutworm (Agrotis spp.), which chew the roots and rhizomes. If the selected area is infested with these pests, either serious soil fumigation has to be made or other growing site should be chosen.

3.1.2.6. The natural vegetation of the area, plants of surrounding places

It is important to know the original flora of our growing site, because later the natural vegetation will appear from time to time disturbing the growing cultures. Plants of surroundings (e.g. forest or forest belt, field, meadow, pasture) can also influence the cultivated stands affecting their living circumstances. Positive effects of surrounding vegetation: these can moderate the wind‟s speed and protect the soil; reduce the rate of evaporation and increase the atmospheric and soil moisture content; these are natural territory delimiters and living spaces for pollinating insects. But besides these we should calculate with some negative effects too, such as: surrounding plants can deprive nutrients and water, can negatively affect the microclimate and may shade, these can facilitate the multiplication of pests and pathogens and their weeds can cause problems too.

3.1.2.7. Proximity of high-traffic roads

Cultivation on territories along high-traffic roads should be avoided in case of medicinal plants (too), because the risk of heavy metal pollution is outstanding there, which impairs the quality of produced product or even makes it unsalable. Furthermore, the proximity of high-traffic roads disadvantageously influences the insect pollination and because of winter road salting the soil‟s salt content may increase, which later inhibits the development of cultivated plants.