Hartkemeyer / Zeng / Böken The Chinese Yams (Dioscorea Batata)

Historical, botanical and health aspekts of the light root
1. Auflage 2025
ISBN: 978-3-6951-7444-7
Verlag: BoD - Books on Demand
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 188 Seiten

The Chinese Yams: Dioscorea Batatas (6th revised edition, January 2025) by Dr. Tobias and Julia Hartkemeyer explores the historical, botanical, and health aspects of the Chinese yam, also known as the light root or Lichtyam. This comprehensive work delves into the plant's taxonomy, ethnobotany, cultivation, nutritional properties, and medicinal significance, drawing on contributions from experts in biodynamic farming, Traditional Chinese Medicine (TCM), and anthroposophic principles. The book traces the yam's ancient origins, its cultivation across Asia, Africa, and the Americas, and its introduction to Europe over 150 years ago. It highlights the plant's cultural and nutritional importance, notably at Andreashof in Ueberlingen, where biodynamic methods enhance its quality. The text covers the yam's morphology, growth cycle, and cultivation practices, emphasizing its adaptability to various climates and soils. It also discusses its bioactive compounds, such as diosgenin, and their pharmacological benefits, including potential hormonal and anti-inflammatory effects. Innovative quality assessment methods, like biophotonics and eurythmic treatments, underscore the yam's unique "light storage capacity" and vitality, aligning with Rudolf Steiner's anthroposophic insights. The book includes practical applications, such as recipes featuring the light root, and profiles successful cultivation at Andreashof. Engaging and multidisciplinary, this work invites readers to explore the Chinese yam's rich heritage and potential in modern nutrition and medicine. Read the full book for in-depth insights into this remarkable plant.

Autoren/Hrsg.

Hartkemeyer, Tobias

Zeng, Jing

Hartkemeyer, Julia

Böken, Noëmi

Busl, Matthias

Hagg, Sabine

Küpper, Ute

Ramm, Hartmut

Schleyerbach, Bettina und Peer

Schmidt, Nicolai

Leseproben

2. CULTURAL DESCRIPTION OF

MORPHOLOGY

Like all Dioscorea species, is a perennial. In many botanical textbooks they are classified as monocotyledons, but Ayensu (1972) doubts this. According to him, dicotyledonous embryos have also been observed (Ayensu, 1972). Its twining shoots can grow to a length of 8 to 10 meters. During the growing season from May to October, the tendrils become woody almost to the ends of their shoots. The leaves of are heart-shaped (up to 8 cm long and 6 cm wide). The leaf position on one and the same plant can be alternate or opposite. The many small white flowers (dioecious) have the pleasant scent of cinnamon. They form small, loose racemes, each individual flower of which is only 2 to 3 mm in size. The seed capsules of the female plants resemble beechnuts (Fig. 34, p.114). The seeds are generally not very fertile (the germination rate is about 2%). Male and female plants produce bulbils, small above-ground tubers that form in the leaf axils on the tendril and with which they can reproduce vegetatively. The roots form starchy, bulbous thickenings in a wide variety of shapes. There are various statements on the size and weight of the tubers; for example, Chittenden (1956) states that they can reach a depth of over one meter. A root tuber grows to a length of 100 cm within two years and can reach a good 10 cm in diameter. At this stage, the root tuber can weigh up to 2 kilograms. As it is a perennial plant, older specimens can weigh many times more.

FIGURE 3: MORPHOLOGY OF DIOSCOREA BATATAS

(Source: Lemure & van Houtte, 1855)

Figure 4: DIOSCOREA BATATAS/LICHTYAM: TENDRILS WITH FOLIAGE LEAVES AND BULBILS PHOTOS: M. BUSL

Figure 5: INFLORESCENCE OF MALE D. BATATAS (4-6 CM LONG)- SMELLS OF CINNAMON AND VANILLA

Figure 6: DIOSCOREA BATATAS: THE INFLORESCENCE OF THE FEMALE PLANT IS ABOUT TWICE AS LARGE AS THE MALE (6-12 CM LONG, LOCATION ÜBERLINGEN-BONNDORF 2012)

(Source: Gilg & Schumann 1900)

FIGURE 7: MORPHOLOGY OF DIOSCOREA BATATAS: INFLORESCENCE

SITE FACTORS

requires deep, well-drained soils for optimal growth. Compacted subsoils and waterlogged sites are unsuitable. The species thrives in a pH range of 5-7 (Franke 1994). Since commonly occurs in alluvial landscapes, it typically grows in silty clay soils characteristic of these environments (Beyerl 2001).

Soil structure is critical for tuber development, as the tubers penetrate the soil directly rather than forming from thin roots. Dense, waterlogged soils promote tuber rot. To ensure adequate soil loosening and aeration, tillage requirements increase proportionally with fine soil content (Franke 1994).

CLIMATIC CONDITIONS

can survive in a number of different habitats and climatic conditions; in the wild, it usually grows in bright clearings along the edges of tropical floodplain forests (Yayskievych 1999). It therefore has a relatively high demand for warmth. Optimal temperatures are between 20°C and 30°C. The leaves are very sensitive to frost; they can freeze at 1°C. However, the root tubers can also be left in the soil over winter (Thompson, 1878) if the frost does not penetrate too deeply into the soil during this time. Sufficient humidity and a continuous supply of water are necessary for good growth. Franke (1994) writes of annual precipitation between 1,100 and 10,000 mm. In the first five months after planting, the soil must therefore be well and regularly moistened. Periods of drought should not exceed 4-5 months. The cultivation period is between 8-12 months. Yields are higher under alternately moist conditions than in constantly moist areas (Franke 1994).

REPRODUCTION

generally reproduces asexually. Although it is capable of generative reproduction, there are no documented observations of this in North America. One reason could be the dioecious nature of the plant, another could be that female plants have not been observed growing in the wild (Beyerl 2001). According to Fernandez (1995), 38% to 94% of the flowers and 70% to 87% of the seeds wither, so that reproduction via the seeds is low. Only the males were cultivated on the Pente farm. One year, however, we also had a female plant. Its seeds were infertile. can reproduce vegetatively through the buds that form particularly on the upper part of the large tuber. The shoot fruit nodules (bulbils) are also used for vegetative propagation. The emergence rate here is almost 100%. The root tubers that form from bulblets within one growing season usually do not reach their full size. These tubers are therefore used as planting material the following year and are planted out again. They only reach a marketable size after the second year. The roots that serve as planting material do not continue to grow themselves, but usually form one, sometimes two or three new root tubers of different sizes from the vegetation points, some of which can be used again as planting material for the following year.

At least 20 bulblets are formed per plant each year (depending on the heat sum and vegetation period), usually many times more. Two weeks after sowing, the latter can already germinate. Bulbils are also capable of germination and can grow into complete plants. Even partially eaten bulblets (e.g. by rodents) or bulblets cut by the plow are capable of producing healthy plants (Beyerl 2001). If a root tuber is cut into 4 cm long pieces, new plants can also grow from it. According to Franke (1994), when cutting large tubers, the top part is better suited than the end of the tuber, which in turn is better than the middle part. In some southern states of the USA, has already attained the status of a weed due to its vegetative vigor.

GROWTH CYCLE

According to Fernandez (1995), the growth cycle of a can be divided into four different phases.20 They are briefly summarized below:

The dormant phase of the planting material. In Dioscorea species it lasts about six weeks from the beginning of the shoot. During this time, their growth is characterized almost exclusively by the development of a lush root system and the longitudinal growth of the shoot. The leaves grow very little during this phase, meaning that almost no photosynthesis takes place, so that the plant is dependent on the mobilization of reserve substances from the plant tuber. The dependence of the shoot on the tuber can be easily observed if it is separated from the tuber soon after sprouting. The shoots of the previously robust shoot are now weakly developed and no longer as strong as before. After separation from the tuber21, the plant no longer has any reserve substances available and has to feed itself via the still weakly developed root system.

This phase is characterized by the development of the leaves. This begins around the sixth week. The foliage is fully developed by about the tenth week, and from the thirteenth week onwards, the leaf area increases only slightly or not at all. The root tubers continue to grow during this phase, but from the tenth week, they become only slightly longer. While the old tubers partially dry out and mummify, the new root tuber emerges. During this second phase, the shoots continue to grow. At the end of this phase, the plant produces a surplus of carbohydrates, and the tubers develop from the tenth or eleventh week.

Here, in particular, tuber growth increases. This lasts until around the eighteenth week from the start of sprouting. All of the leaves and tendrils that emerged in the second phase are now used for photosynthesis to produce reserve substances that are stored in the tuber. The tuber grows until the end of the growth period, after which the fourth and final phase of the growth cycle begins.

The tuber now matures. The foliage and tendrils begin to age and at the same time the dry weight of the tuber decreases. The tuber then enters dormancy and will normally only begin to sprout one to four months later (Fernandez 1995).

Figure 8: Growth cycle (Source: Sobulo 1972)

CROP ROTATION

Crop break periods (typically four to five years) and general crop rotation principles vary by country. After several years of using the same soil in boxes, tubs, and containers, signs of soil degeneration may occur.

FERTILIZATION

According to Beyerl (2001), prefers soils that are relatively rich in nitrogen, but no further details are provided. Chinese cultivation literature even states that cannot be overfertilized. In conventional cultivation, yams respond clearly to nitrogen fertilization, less markedly to potassium, and very limitedly to phosphorus. Potassium promotes tuber growth. The highest nutrient requirement occurs when 60% of the planting material has sprouted (Franke, 1994). According to Hildebrandt (2005), manure, compost, and other organic fertilizers are well utilized by .

20 The duration of the growth phases shown here differs depending on the time of planting.

21 The tuber is a fleshy thickened organ, it is a metamorphosis of the root or the shoot axis and serves as a store for reserve substances. The edible part of the yam root is therefore actually a yam...