**2. Background and cultivation technology of Chinese medicinal herbs under forest**

#### **2.1 The background of Chinese medicinal herbs**

Chinese herbs are the important raw material for pharmaceutical production and the material basis for the inheritance and development of traditional Chinese medicine (TCM) for thousands of years. It is also a strategic resource related to the national economy and people's livelihood. As an important support of economic development

in many poor areas, it plays a positive role in increasing farmers' income [3]. The clinical value of TCM has progressively been appreciated by the public at home and abroad, particularly the effect shown in the COVID-19 prevention and control, which has demonstrated its unique efficacy and role [4]. With the increasing global population and the complication of disease types, the demand for Chinese herbal medicine continues to rise. It shows a vigorous development trend in the Chinese herbal medicine industry. Historically, the supply of Chinese herbal medicine commodity mainly depends on wild plant resources [1]. Nevertheless, with the soaring demand for medicinal herbs, natural medicinal herbs have been mined out, and artificial farmland cultivation has gradually been adopted. Since the 1950s, China has vigorously developed the production of Chinese herbal medicine, from introduction and trial planting to commercial planting to base cultivation. The planting industry of Chinese herbs has experienced four periods: the germination period, the development period, the growth period, and the prosperity period [2]. However, some problems occurred with the gradual increase in the planting scale and yield of Chinese herbs that require urgent solutions.

First, the quality of Chinese herbs is unstable. At present, the circulation market of Chinese herbs is mixed with different varieties, including wild varieties, semi-wild varieties, wild cultivation, cultivated varieties, genuine land varieties, introduced varieties from different places, etc. [5]. The multichannel sources of TCM lead to its uneven internal quality, which not only increases quality security control difficulty of TCM, but also has a negative impact on the processing of TCM decoction pieces and TCM preparations [6]. The quality of Chinese herbs is affected by various objective elements.

Second, the problem of pesticide residues and excessive heavy metals is prominent. As the market demand for TCM continues to increase, wild medicinal materials have been hollowed out, and its yield has been unable to meet the demand, so most of the medicinal materials have to be cultivated artificially. In the process of cultivation, the high-yield mode of crops was copied for Chinese herbs, and a large number of chemical fertilizers, expansion, and other chemicals were applied, resulting in high yield but low medicinal effective component. The quality of medicinal herbs declined, and the efficacy of Chinese herbs was generally doubted [7]. Moreover, in the large-scale agricultural production of traditional Chinese medicine, pest became severe, and farmers have to apply chemical pesticides in order to guarantee the output, but the lack of scientific management of the field use of pesticides leads to the existence of different degrees of pesticide residue in medicinal herbs [8]. Exogenous harmful residues of medicinal herbs mainly include pesticide residues, heavy metals, polycyclic aromatic hydrocarbons (PAHs), and others [9]. Unreasonable use of pesticides leads to uneven quality of TCM decoction pieces and cannot guarantee their safety [10]. The quality problems of pesticide residues and excessive heavy metals restrict the international development of traditional medicine [11]. The 2020 edition of the Chinese Pharmacopeia has more stringent restrictions on pesticide usage; besides, the European Union, Japan, and South Korea impose severe restrictions on pesticide residues and heavy metals. The Chinese herbal medicine industry will face more serious challenges.

Third, the continuous cultivation disorder of Chinese herbs is serious, and most areas producing genuine medicinal herbs face the risk of having no land to grow [12]. With the increasing demand for Chinese medicine materials, the types and scale of artificial cultivation of that are increasing, but the problem of continuous cropping in cultivation is becoming increasingly prominent, which seriously affects the normal

#### *Cultivation Practice of Chinese Medicinal Herbs DOI: http://dx.doi.org/10.5772/intechopen.104859*

growth and medicinal value and brings great trouble to the development of Chinese medicine [13]. Most of the TCM materials copy the agricultural high-yield mode; however, the reality is that crop varieties have adapted to the high-yield mode after thousands of years of genetic transformation, while the research and development of medicinal herbs are insufficient to support the high-yield mode. Therefore, the application of agricultural high-yield mode has caused major problems such as high yield but low quality, excessive pesticide residues, and continuous cropping obstacles in the production of Chinese herbs. About 70% of the root Chinese medicinal herbs are slow-growing perennial herbs that take many years to reach reproductive maturity; these plants usually experience different degrees of replant obstacles [12, 14]. In addition, most medicinal herbs are not fertilizer-resistant, and soil eutrophication leads to serious obstacles to continuous cultivation. A crop of cultivated land cannot be replanted for several decades, which leads to the serious phenomenon of deforestation for planting Chinese herbs, and most authentic producing areas face the embarrassing situation of having no land to plant, which seriously restricts the sustainable development of the Chinese herbal medicine industry [15, 16].

Around these problems, agricultural scientists in China took the research on large varieties of Chinese herbs such as *Panax notoginseng*, *Panax ginseng*, and *Dendrobium nobile* as a breakthrough point to explore and form a rule that follows the natural growth and development of medicinal herbs, that is, to use under-forest resources to make medicinal materials return to wild forests, and establish the planting mode based on the efficacy of medicinal materials as the first principle, and gradually form a set of perfect theoretical and technical systems to solve the problem of quality decline of Chinese herbs from the source, which provides a strong technical guarantee for the healthy development of the Chinese herbal medicine industry. Theoretical basis of medicinal herbs under forest [17–23].

In the agroforestry system, agroforestry intercropping mode can not only significantly improve the microclimate conditions under forests by reducing soil erosion and wind speed, but also improve soil fertility and crop yield [24]. This pattern can make full use of natural resources and improve the efficiency of land use. Currently, the agroforestry intercropping mode has been successful in walnut/mung bean [25], poplar/soybean [26], jujube/cotton [27], etc. Therefore, the agroforestry intercropping model provides an effective and scientific way to alleviate the shortage of land resources and realize sustainable utilization.

#### **2.2 Cultivation technology of Chinese medicinal herbs under forest**

A typical example for explaining planting technology is *Panax notoginseng* (Burk.) F. H. Chen cultivated under forest [28]. *P. notoginseng* belongs to Panax genus, the Araliaceae family. It is one of the most famous Chinese traditional medicinal herbs. It is a rare medicinal herb unique in China and has the functions of promoting blood circulation, dispersing blood stasis, reducing swelling, and relieving pain. As a medicinal herb, *P. notoginseng* has been used for hundreds of years. It was first recorded in Compendium of Materia Medica by Li Shizhen in the Ming Dynasty. The main components of *P. notoginseng* are polysaccharides and saponins and also contain a small amount of flavonoids and volatile oil, as well as trace metal elements and other substances, among which saponins are the main medicinal components. The cultivation of *P. notoginseng* requires very special environmental conditions, including altitude, climate, and soil. Yunnan Province and Guangxi Province are the main planting areas, among which Yunnan province accounts for more than 98% of the total planting

area in China [16]. Moreover, Yunnan Province is the authentic production area of *P. notoginseng*, and its yield and quality are better than other those in production areas.

Due to its high medicinal and economic value, *P. notoginseng* has attracted more and more attention. However, pesticides residues and heavy metals overuse, continuous cultivation obstacles, and unstable quality, etc., threaten the development of Chinese medicines. Facing these problems, we had explored the roads under the lead of outstanding phytopathologist Zhu youyong from Yunnan Agricultural University. We have been engaged in the research and promotion of ecological cultivation of high-quality *P. notoginseng* for many years. The previous study of our group showed that Yunnan Pine and Simao Pine have a high canopy density, which is suitable for the shade-demand growth of *P. notoginseng*. The volatiles of pine trees have the effect of pest control. Organic matter formed by the degradation of pine needles is also beneficial to the healthy growth of *P. notoginseng*. In 2015, our group carried out the test for *P. notoginseng* cultivation under the forest of Simao Pine at the altitude of 1500 m ~ 1900 m in the Zhutang Town of Lancang County in Yunnan Province. After 2 years, this innovative cultivation mode achieved success. The technical standards for *P. notoginseng* cultivation under forest were established, and three local standards were issued on June 11, 2020, which promoted poverty reduction in China and was conducive to the rational use of forest resources.

The key technologies for *P. notoginseng* cultivation under forest include forest land selection, land tillage, seedling breeding and transplanting, and on-farm organic management. Using these key technologies can realize the standardization and largescale production for *P. notoginseng* planting under forest, and the quality and safety of *P. notoginseng* can be effectively improved without applying chemical pesticides and chemical fertilizer in the production process.

#### *2.2.1 Forest land selection*

When carrying out the under-forest organic planting for *P. notoginseng*, artificial forestlands and the tree species that have no negative effects on the growth of *P. notoginseng* such as Yunnan Pine, Simao Pine, Huashan pine, Chinese fir, etc., could be selected. The forest canopy density should be 0.7 ~ 0.9 for the growth of *P. notoginseng*, and forest land with slope ≤ 25° could be able to be used for planting because of ecological conservation and.

In addition, the suitable soil for *P. notoginseng* is sandy loam soil or loam soil, and the soil pollutant content should meet the requirements of national standard GB15618. Selected forest land should have not been planted with any crop for at least 8 years so that it meets organic production.

#### *2.2.2 Under-forest land tillage*


of forest tree planting. The slope land should be ridged along the contour line. The ridge surface is arranged in a circular arc, and the distance between the ridge and the tree root is greater than 20 cm. The ridge height is adjusted according to the slope. When the slope is greater than 20°, the ridge height is about 30 cm. When the slope is less than 20°, the ridge height is about 40 cm.

4.Setting up the drainage ditches. Drainage ditch is necessary in rainy season, and it is set up according to different slopes and terrain and leaves a drainage outlet every 15 m ~ 20 m length of the ridge. The drain outlet should be cleaned timely to prevent tree branches or soil accumulation from obstructing the drainage.
