Cultivation Methods and Technical Key Points for Notoginseng
Notoginseng originated in the Tertiary period and is a relict plant of the ancient tropics, with an extremely narrow distribution range, which is mainly related to Notoginseng's physiological and ecological adaptability to the environment.
Notoginseng is a perennial herbaceous plant with persistent roots, and has one growth cycle each year. Usually, Notoginseng more than two years old has two growth peaks within one growth cycle: the vegetative growth peak from April to June and the reproductive peak from August to October. The germination temperature of Notoginseng seeds is 10-30 degrees, the optimal temperature is 20 degrees, and the seed dormancy period is 45d-60d. During the dormancy process, seedlings need to undergo a period of low-temperature treatment before they will germinate, and they are very sensitive to light; it is traditionally believed that 30% natural light is needed for normal growth and development, hence the saying for Notoginseng shade sheds: "three parts light, seven parts shade"; according to the latest research, the most suitable light transmittance for Notoginseng sheds is 8%-12%, and growth will be adversely affected when it exceeds 17%!
From sowing to harvest, Notoginseng requires more than 3 years; the roots of one-year-old Notoginseng are usually used as seedlings, and plants from the second year onward can flower and set seed. Generally, buds appear in July, flowers open in August, seeds set in September, and fruits mature in batches from October to November.
The main production area of Notoginseng in Yunnan Province is located on a low-latitude plateau. The climate is characterized by long summers and warm winters, relatively abundant heat, and relatively small annual temperature differences. The annual average temperature is 15.8-19.3°C (Yunnan Provincial Meteorological Bureau Data Office, 1982). Within a year, except from mid-December to mid-February of the following year, when low daily temperatures of ≥0.0°C occur, the multi-year average minimum temperature is 0-2°C. The number of days with a stable daily average temperature of ≥10°C over the years is 265-307 days, and the annual effective accumulated temperature reaches 4863.7-6436.8°C. In summer, due to concentrated rainfall, solar radiation decreases markedly, forming an average temperature of 21.5-22.5°C from June to August. The suitable temperature and moisture conditions provide a superior natural environment for the growth and development of Notoginseng. In winter, the monthly average temperature is 11°C, and aboveground growth has already stopped, but at this time the 5cm soil temperature still remains 14°C (regional average). This is the reason why Notoginseng stems and leaves can still remain vital in winter. The relatively high soil temperature is beneficial to the accumulation of nutrients in the roots, and is especially favorable for the morphological development of embryo after-ripening of seeds already sown into the soil. The embryo after-ripening period can be naturally completed by passing through the winter stage, which provides extremely favorable conditions for Notoginseng seedling raising and for increasing the seed emergence rate. Such uniquely favorable natural ecological conditions are an advantageous factor for Wenshan Prefecture in developing Notoginseng production.
The landforms of the Notoginseng production area are complex, and the terrain rises and falls greatly, causing significant vertical differences in temperature. In winter and spring (December to April of the following year) and in late summer and early autumn (August-October), under the influence of cold air intrusions from atmospheric circulation, short-term and local frost damage and low-temperature disasters are caused, especially low-temperature chilling injury. Although snowfall and frost phenomena have not occurred, and the temperature has not dropped to the 0°C frost point, the harm caused by a sudden drop in temperature below the critical value for crop growth is relatively great, and such situations may occur about once every few years. In production areas of Funing County below 500m altitude, summer temperatures are relatively high, and coupled with the foehn effect and local circulation influences, the temperature tends to rise further, and weather with a daily maximum temperature of ≥35°C may occur. Evaporation intensifies, and plants may very likely wilt. When the above two situations occur, proper measures must be taken to minimize losses as much as possible.
Through cultivation practice, it has been learned that during the growth process, Notoginseng should receive diffused light and must absolutely avoid direct exposure to strong sunlight.
Notoginseng is a typical shade plant, and this ecological habit is consistent with the structural characteristics of Notoginseng itself. Farmers experienced in Notoginseng cultivation generally regard the suitable light conditions during the growth and development period of Notoginseng as roughly three parts light and seven parts shade, and in specific practices they also make distinctions according to the age of the Notoginseng plants and the light transmittance requirements at different growth stages. According to the climatic conditions and growth-stage characteristics throughout the year, the light transmittance in the garden is regulated by adjusting the density of the shading material on the overhead shed. For example, in early May, which is the early growth stage of various types of Notoginseng seedlings, annual precipitation is relatively low, solar radiation is relatively strong, and sunshine duration is long. To maintain the normal growth of Notoginseng seedlings at this stage, shading should be appropriately increased, and the light transmittance in the shed is about 25-30%. After entering the rainy season, because cloud cover increases, atmospheric humidity rises, sunshine duration is shorter than in spring, and total radiation is also lower, while Notoginseng is entering its vigorous growth period. At this time, shading should be reduced and light in the garden increased, and light transmittance can be increased to 40%. The specific amount of shading in the garden to control must be determined according to the actual local conditions at the time, and mechanical copying must be avoided.
The climate of the Notoginseng production area, like that of the whole province, has very distinct dry and wet seasons. Annual precipitation in Wenshan Prefecture is relatively abundant, with the average precipitation across locations in the past 10 years being 1163mm. In the southern region it reaches more than 1300mm. The growth and development period of Notoginseng requires a relatively moist environment. Normal growth of the plants requires maintaining 25-40% soil moisture, and also requires the relative humidity in the Notoginseng garden to reach 70-80%. During the rainy season, because more than 80% of annual precipitation is concentrated from May to October, the garden can rely on atmospheric precipitation during this period. In some areas, soil permeability is high, and as long as there are relatively many consecutive days without precipitation, drought may form, and artificial irrigation is then needed in the garden to maintain a certain humidity. Artificial regulation of water is mainly in winter and spring. At this time the weather is clear, sunshine is abundant, precipitation is scarce while wind speed is high, evaporation is strong, and soil moisture decreases rapidly. At this time, in addition to artificial irrigation, attention must also be paid to proper field management, using mulching grass on the bed surface and adjusting the covering of the overhead shed in the garden to maintain humidity in the garden. At the same time, attention must also be paid to the special water requirements of Notoginseng seedlings at different growth and development stages, such as from sowing to the seedling leaf expansion stage, the emergence stage of seed strips, and the stage when green fruits turn red. When drought occurs, irrigation for drought resistance must be carried out to prevent physiological drought, which directly affects the red seed harvest.
Annual precipitation varies from place to place, so it is necessary to base decisions on local specific conditions. At the same time, when selecting and building a Notoginseng garden, water source conditions should be considered as an important issue. In years or areas with relatively high annual precipitation, flood control and drainage should be carried out after heavy rain or rainstorms, and accumulated water in the garden should be drained promptly. If soil water content is excessive and aeration is poor, and if the garden remains in a waterlogged state for a relatively long time, it directly endangers plant survival and may cause Notoginseng root rot and death. When relative humidity in the garden is too high, it easily causes outbreaks of various diseases, which cannot be ignored in daily management. It is the basis for the survival of Notoginseng. Through the soil, plants obtain the water, nutrients, air and heat necessary for survival. The structure, fertility and permeability of the soil directly affect the growth and development of Notoginseng. Cultivation of Notoginseng in Wenshan Prefecture has spread throughout all 8 counties of the prefecture. The altitude of the production areas varies strikingly, with Notoginseng planting areas from 340-1800m altitude. The complex landforms create prominent spatial differences in conditions such as heat, water and soil, directly affecting the water and heat conditions of local areas. In addition, the types of soil-forming parent rocks are diverse, and the natural differences in soil texture and soil fertility are relatively large.
Notoginseng can grow almost in acidic red soils and yellow soils with relatively heavy clay, poor permeability and pH 4.5-5.6, and can also grow in near-neutral black sandy loam. This is entirely the result of long-term human production activities. Through various production methods such as plowing, fertilizing, irrigation and crop rotation, soil structure has been improved to a certain extent and soil fertility has been raised, which is also the reason for differences in Notoginseng growth vigor and yield between new and old production areas. Therefore, in developing Notoginseng production, soil use must emphasize both use and maintenance, and rational fertilization should be carried out according to the characteristics of local soil quality and fertility. Through correct cultivation methods, coordinate the conditions of water, fertilizer, air and heat in the soil, create suitable living conditions for microorganisms, accelerate organic matter mineralization, promote nutrient increase, gradually improve soil structure, raise soil fertility, and prevent soil deterioration. Especially in mountainous areas where irrigation is difficult, strengthen field management, adjust nutrient conditions, and gradually raise soil fertility, so that the soil develops in a direction favorable to human activities.