G63

Chemical Optical type or Density rotation comment Ref.

Distilled from the drug Distilled from the drug Distilled from the drug Distilled from the drug Distilled from the drug

Traces are given with 0.1% to be able to grade them. n.d. or not detectable are given with 0.0.

like in the Hungarian Puzsta or in Argentina are duly tolerated. As a matter of fact, however, chamomile has to be sown on a smooth and solidified field to make sure that the fine seeds (thousand kernel weight 0.02 to 0.06 g with diploid forms and 0.04 to 0.12 g with tetraploids) are not washed in the soils due to rainfall. The soil should therefore be prepared on a flat working level only; it should duly settle before sowing is done and it should be solidified by means of a roller. The seeds require a lot of humidity for germination and for a quick juvenile development.

5.1.3 Flowering

True chamomile flowers over a longer period and produces new flowers. For the cultivation this is taken into consideration by a multiple harvest of flowers. The flowering time can last about 50 to 65 days. It takes about 20 to 35 days before a flower is fully developed. The relatively short vegetation period of 150 to 180 days also allows a cultivation at higher altitudes up to 500 m.

5.2 methods of cultivation

Cultivation measures such as sowing time, fertilization, weed control, and harvest have to be arranged in such a way that the yield properties and those of quality fixed in the genotype ensure an optimum development.

5.2.1 Cultivation Procedure

In 1956 Heeger still reported that with respect to cultivation chamomile had been worked on to a small extent only [40]. Over the past 40 years rapid development could be observed. Preference is given to chamomile being cultivated. In most countries extensive field cultivation with mechanized sowing, nursing, harvest, and processing has gained acceptance [13, 28, 38, 75, 84]. In nearly all companies specializing in cultivation, technological innovations have been tested and introduced repeatedly. Often technological solutions are quite specific to the companies and having been adapted to the locations and varieties were developed for the individual sections of production [62, 68]. Therefore, a compilation of a generally applicable sample technology does not seem to be recommended. Some experiences from various countries of cultivation are shown in the paragraphs to follow.

Presently three basic variants — being mostly complementary to each other — are applied: autumn sowing, spring sowing, and cultivation of several years' duration with self-sowing.

5.2.1.1 Autumn Sowing

In the Northern Hemisphere graduated autumn sowing is done at the end of the summer at an interval of about 8 to 14 days, from the beginning to the end of September. A precondition is, however, that the anticipated fruit is removed as quickly as possible. If sowing is done too early, this leads to premature formation of shoots [16]. Both plants developed too far as well as those that are too small die in winter. Chamomile should start the winter months at a stage of six to eight leaves. At this stage it is definitely cold resistant. Autumn sowing means that the best yields are achieved with the possibility of a long vegetative developmental and tillering phase within the physiological short day. Being largely independent from the sowing time, the flowering period starts with an achieved day length of about 17 hours (in central Europe at the end of May/beginning of June). Due to the fact that flowering generally starts at the same time, the possible cultivation area is strongly determined by the harvest and drying capacity. Even if chamomile is flowering over a longer period, producing new flowers again and again temporarily, the first harvest process has to take place according to exact timing. Thoroughly ripening flower heads favor plant aging. Overripe flowers strongly tend to fall apart during the drying and preparation process after the harvest [50]. Seeds dropping out mean a burden to the location in the years to follow, changing the spectrum of active principles [18, 24, 30, 81].

5.2.1.2 Spring Sowing

The advantage of spring sowing is the possibility of graduated steps of cultivation in order to be able to utilize the harvesting and drying technique to the maximum by temporally graduated harvest dates. In central Europe it is a usual practice to start sowing in March at an interval of about 14 days. It is, however, a fact that the yield and the homogeneity of the populations decrease the later sowing is done. The pressure of contamination by diseases and infestation by parasitic insects in the course of the summer months increases just as well [21].

5.2.1.3 Cultivation of Several Years' Duration by Self-Sowing

With extensive production, a cultivation of several years' duration is possible on the same field considering that the population is being formed by the chamomile seeds that dropped out. Additional seeds may also be sown. After the last economically justifiable harvesting passage, the population remains on the field for a few more days and the plants are mulched. The next step is a non-turning superficial soil preparation. From September onward the self-sown seeds germinate, which may be compared with a thick carpet. This procedure is similar to broadcast sowing without a drilling machine. The strong competitive capability of chamomile against weed, the possibility of utilizing a harrow and a chain harrow or curry-comb for weed control, and thinning out make the procedure a cheap alternative. Companies particularly in Germany, Argentina, Hungary, and in the Czech Republic have practiced this procedure on the same field for nearly ten years. In the total remaining area the weed is reduced by taking the autumn chamomile from the crop rotation. The yields to be expected and the other peculiarities of this procedure may be compared with those of the sowings done in autumn. This form of cultivation is not recommended for the flower production of breeding lines, especially with the cultivation of defined chemotypes, because of the uncontrolled procedure of the pollination as a germination of wild (i.e., nonbred) chamomile or a segregation with hybrid seeds may occur in the following year.

Especially with autumn sowing slightly humid locations are more favorable than regions with plenty of summer rains where chamomile tends to have a luxurious growth of herb and leaves; consequently it is less suitable for being harvested and shows a lower content of active principles. The development of chamazulene substantially depends on the duration of sunshine and the day temperatures from the time of the formation of flower buds.

It is reported repeatedly that chamomile is self-compatible [16, 19]. Experiences regarding cultivation of several years' duration and self-sowing point in the same direction. Precise indications concerning the value of different fruit rotations are missing but it is a fact that chamomile grows particularly well in fields free from weed; viz., after root crops such as potatoes and sugar-beet, maize, winter cereals, and leguminosae. Using fields for the production of chamomile for several years has also proved to be a success. Chamomile should generally be cultivated as final crop in the rotation without any N-fertilization. A high content of Nmin in the soil leads to strong vegetative growth, makes the harvest more difficult, and can finally also lead to a lower content of active principles. Weeds cause problems for the cultures to follow. First of all a nonturning superficial soil preparation should in any case take place after the chamomile cultivation to stimulate the germination of chamomile seeds dropped out, to be followed by mechanical weed control in autumn. In course of the following year a culture is started after refertilization, being tolerant against herbicides combating chamomile.

Chamomile particularly absorbs the heavy metal cadmium from the soil [78], at least it concentrates due to the mobility in the flowers like with other flower drugs, e.g., St. John's wort

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