what is stevia

Stevia rebaudiana (Bertoni) Hemsl.) is a perennial herb of the genus Stevia in the composite family. Plant height 1-1.3 m. Root tip hypertrophy, 50-60, up to 25 cm long. Stem erect, base tip woody, upper tender, dense short fuzz, corolla base light purplish red or white, upper white. Achene linear, slightly flattened, brown, crested. Flowering July – September, fruiting September – November.

Alpine grassland native to the border of Paraguay and Brazil in South America. Since 1977, it has been introduced and cultivated in Beijing, Hebei, Shaanxi, Jiangsu, Anhui, Fujian, Hunan, Yunnan and other places. The species likes to grow in a warm and humid environment and is sensitive to light. The leaves contain 6-12% inulin, the fine white powder form, is a low calorie, high sweetness of natural sweetener, is one of the raw materials of food and drug industry.
Morphological characteristics
stevia
stevia
Herbs perennial, 1-1.3 m tall. Shallow roots, consisting of primary and secondary roots. The root distribution depth is 20-40 cm, the biennial roots can germinate several to dozens of stems in the next year, can be ramet reproduction. Root tip hypertrophy, 50-60, stem erect, round. Annual seedlings for a single stem, perennial after the cluster. Woody base tip, soft upper, densely short fuzz,

Leaves simple opposite or upper part of stem, a few tricolor, leaves short, obovate or lanceolate, margin lightly serrate, short down on both sides, green or thick green, veins, very sweet. Leaves with similar moldy white hair production, is the normal secretion of SAP, more common in rainy days due to collection.

Inflorescences small, bisexual flowers, involucre tubule, involucre bracts 5-6 layered, margins equal; Receptacle flat, bald and clean; Corolla base pale purplish red or white, distally white. Achene linear, slightly flattened, brown, crested. About 0.4g seed weight, no dormant period, easy to lose the ability to germinate, life span is not more than a year. Late July – early August for the bud period. Flowering July – September, fruiting September – November.
The geographical distribution of
Native to Paraguay and Brazil in South America. Stevia was introduced from Japan in 1977 by Nanjing Zhongshan Botanical Garden and successfully planted in 1978. It is introduced and cultivated in Beijing, Anhui, Hebei, Shandong, Shaanxi, Jiangsu, Gansu, Xinjiang, Yunnan and other parts of China.
Stevia likes to grow in warm and humid environment, but can also tolerate -5℃ low temperature, the temperature is 20-30℃ best for stem and leaf growth. Stevia is a short-day plant with strong sensitivity to light. The critical day length is 12 hours, especially in the growing period. Stevia has shallow roots and poor drought resistance. Strong short day. Stevia is a short-day plant with strong light sensitivity. The best growth period is 100-120 days
Breeding methods
stevia
stevia
On seed reproduction and production, the method of planting and then transplanting is adopted. In the southern provinces of China, flat beds are usually used for sowing seedlings, while hotbeds are used in the north. In the south bank of the Yangtze River, the sowing time is suitable for 10-1L months. Seedlings overwinter in the growing border and can be transplanted to the field for cultivation in the middle or late March of the next year. In the north, the greenhouse or hotbed is usually used to sow seedlings in 24 months. In order to make the seeds spread evenly, before sowing can use fine sand to mix the seeds to rub, and then put in warm water soak 10-12 hours, and then use a small amount of plants and plants to mix seeds. After sowing, gently press the seeds with wood to make contact with the soil, and then spray water to the bed surface with a sprayer 1 times to keep the bed wet and improve the seedling rate. Suitable temperature and humidity, after sowing 7-10 days can sprout unearthed. Sowing quantity: 500 grams per 100 square meters seedbed, the actual number of strong seedlings cultivated is 200,000 to 250,000, enough to plant 12-15 mu of land. Generally, 8000-9000 plants are planted per mu, and 10,000-12000 plants can be densely planted.

Cuttings propagation from late March to late August can be cuttings, in order to show the bud before cutting cuttings flaps inserted higher survival rate. Cuttage selection meets the requirements of robust branches, lateral stems, 15-20 cm long section, the cuttings of 1/3- L /2 inserted into the bed soil, plant spacing of 2 cm ×5 cm. After inserting water in time, the top is covered with straw curtain or plastic film, heat preservation at night, avoid direct sunlight at noon, when the new bud is properly ventilated and transparent, gradually exercise the adaptability of seedlings to the outside world, and form strong seedlings with developed roots, robust stems and leaves and normal color.

In addition, although layering can also reproduce, it is only used in seed selection to retain good individual plants, and is not suitable for large-scale cultivation.

Spring planting, planting 1 mu stevia, about 10-20 square meters of seedlings. Rub off the crown hairs before sowing and soak overnight in clean water. When sowing, the seed bed is filled with sufficient water first, after waiting for water infiltration, the seed is sprinkled evenly on the seed bed, and then the seed is covered with fine sand or fine soil, and the seed is half dew and half buried. Finally make arch with bamboo stick, cover seedling bed tightly with plastic film. Generally 5-6 days can sprout, after the emergence of seedlings should pay attention to refining seedlings. When the seedlings grow to 5-6 pairs of true leaves, the temperature above 15℃ can be transplanted. General spacing 30-40 cm; Plant spacing 15-20 cm. When transplanting, pour enough anchoring water.
Cultivation techniques
Folded field management
Phosphate potassium fertilizer as base fertilizer, nitrogen fertilizer as topdressing. The first topdressing is 5-10 days after seedling survival, 10 kilograms of urea per mu, in the growth period, the second topdressing 20-25 kilograms, the third topdressing is carried out after harvest, 15 kilograms of urea per mu, later, weeding and harvesting a topdressing.

Folding harvesting and seed retention
The content of stevioin in leaves was the highest in bud stage, and the drying rate of leaves was also the highest. As long as 30-40% of the plants are in bud, it can be used as the harvest time. Cut the stems about 20 cm above the ground at harvest time and make sure to leave one or two leafy branches per plant to facilitate plant growth. After the harvest immediately take off the leaf booth sun, and strive to dry the day, so as not to become black. Where conditions are available, artificial baking can be carried out with better quality. Stevia likes light for about 10 hours a day. When the plant grows to 40-60 cm, add a cover to block light, so that the seeds can mature for about 10 consecutive days. Stevia is a perennial root crop that can withstand low temperatures and overwinter. Next spring, the old roots in the field can be dug up and planted directly in the field.

Fold edit this section of pest control
Foldable blight
Blight is a disease of seedling stage.

Prevention and control methods: (1) Can choose good drainage, loose soil plot seedling; ② Before sowing, 50% carbendazim 2 kg/mu was used for soil treatment; (3) At the beginning of the disease with 1000-1500 borrowed carbendazim spray or 500 times liquid irrigation; ④ Pull out the diseased plants in time, and treat the diseased holes with 3:1 plant ash and quicklime mixed powder.

Folded leaf spot
July – October prone to this disease, harm stems and leaves.

Control methods: (1) Pay attention to drainage in May and June to reduce soil moisture, and more potassium fertilizer to improve plant resistance; ② Spray 50% carbendazim 1000 times liquid spray for prevention and treatment in the early stage of the disease; (3) After harvest, clear the garden, deal with the residual plants, centralized burning.

Folding white silk disease
April – May rainfall more, soil moisture is too large, often prone to this disease, harmful roots.

Prevention and control methods: (1) reasonable planting, pay attention to the field ventilation and light; (2) increase the application of phosphorus and potassium fertilizer to avoid the growth of seedlings; (3) Once the disease is found, immediately pull out, in the disease around the point of lime disinfection; ④ In the early stage of the disease, 50% carbendazim 1000 times solution can be used to irrigate the area to control the spread of the disease.

Folding bridge worm
Also called inchworm or dipstick, mainly feed on leaves.

Prevention and control methods: can protect the natural enemy of inchworm parasitoid parasitoid, or use 40% dimethoate 1000 times dilution spray prevention and control, 20 days before harvest prohibited.

Fold edit this section main value
Folding edible
stevia
stevia
Stevia glycoside is the main ingredient in stevia dried leaves, which not only has high sweetness, low calorie, but also has certain pharmacological effects. Stevia sugar are the treatment of diabetes, blood sugar control, lower blood pressure, anti-tumor, resisting diarrhea, enhance immunity, promote metabolism, and so on, to control obesity, regulating stomach acid, restore nerve fatigue has a good effect, also has significant curative effect for heart disease, pediatric dental caries and so on, the most important is that it can eliminate the side effects of sucrose. In the report of the 69th session of the Joint Expert Committee on Food Additives of THE United Nations Food and Agriculture Organization (FAO) and the World Health Organization (WHO), stevia has no side effects on human body when the daily intake of stevia is below 4 mg/kg body weight. Stevia glycoside is widely used in food and medicine in South America, Southeast Asia and far East. The Ministry of Health of China approved stevia glycoside as a natural sweetener for unlimited use in 1985, and stevia glycoside as an auxiliary sweetener for medical use in 1990.

It is widely used as medicine and diet. Stevia has been approved as pharmaceutical sweetener excipients in China since 1990. Stevia glycoside derivatives also have the clinical effects of reducing hypertension, blood sugar, anti-tumor, improving diarrhea and improving human immunity. Stevia is widely used as a taste correction agent, used to correct the peculiar smell of some drugs, as an excipient for tablets, pills, capsules and so on. Because stevioside is a non-sugar sweetener, it does not produce acid when eaten by bacteria in the mouth. Therefore, candies made from stevioside do not cause tooth decay due to acid production and can be used to prevent dental caries in children. Stevioside is resistant to acid and alkali and heated in the ph4-10 range at 100℃. Its chemical structure will not change and will not produce glucose needed by microorganisms. It is a non-fermentive substance and is often used for food preservation and mildew prevention in medicines. Stevioside is almost not metabolized in the human body and will not produce too much heat after eating, so it is often used to make sweet food for obese patients, stevioside drink or stevioside candy for children, which can prevent obese people from gaining weight and prevent childhood obesity.

Fold the feed
stevia
stevia
Stevia leaf residue rich trace elements and nutrients in the comprehensive, such as amino acid, crude fat, crude fiber, crude protein and vitamin, etc., is a good feed ingredients, it is further processed into feed feeding livestock, can be used to treat livestock and poultry anorexia, fatigue, slow growth, no heat, diarrhea, and respiratory diseases, also can improve milk quality and meat quality, etc. Studies show that stevia stem is extracted and concentrated in activated water at 45-60℃ to prepare animal health drinks and breast lotions, or the dry stevia stem and leaf are crushed, boiled, concentrated and fermented with mineral water, let the livestock directly diet, for the treatment of livestock diseases, have a good effect. Stevia leaf residue mixed in feed, used to feed dairy cows and sheep, can increase the milk sweetness, milk quality and milk trace elements, amino acids and other substances content, and promote milk yield. Adding stevia residue in 5% proportion to poultry feed can prevent diarrhea, regulate digestive function and improve egg production. Stevia can also be used as feed additive to improve the appetite of livestock, horse racing and pets, treat their chronic diseases, and promote the growth of stunted piglets and broilers.

Fold the fertilizer
Stevia residue not only contains high content of organic matter, but also contains a certain amount of minerals such as calcium and magnesium, which can be used as organic fertilizer to improve and fertilize soil. In the actual production, the soil suitable for cantaloupe, watermelon, citrus, tomato and other vegetables and fruits seedlings can be prepared by mixing the decomposed stevia residue with the base matrix according to a certain ratio. This kind of soil can not only promote the rapid growth and development of seedlings, increase the weight of dry and fresh matter of seedlings, but also promote the early maturity of vegetables and fruits and increase their sweetness, which is a good substrate for seedling raising. When stevia leaf residue was added to the culture medium of fungi, it could not only meet the needs of edible fungi for nutrients, but also meet the requirements of various trace elements, vitamins and air permeability of edible fungi, so as to produce bacteria quickly and early, with good bacterial quality and high yield. With stevia residue of soil cultivation of flammulina velutipes, slightly sweet, unique flavor; The cultivated tremella grows white and large.