Method for plan stevia rebaudiana
First, select improved varieties.
Excellent stevia varieties require high A3 glycoside content, high total glycoside content, lodging resistance, strong disease resistance and multi-branching. At present, the main planting varieties are Shoutian No.3, Shoutian No.3 and Jiangdong 1.
Second, cultivate strong seedlings.
The seedling raising of Stevia rebaudiana can be carried out in three ways: seeds, cuttings and old roots, among which cuttings are the most important method for the propagation of Stevia rebaudiana.
1, seedbed preparation
Bed site: choose a place that is sheltered from the wind, sunny and supported by water system to build the bed; Width:1.2-1.4m (2 beds in 4m shed and 3 beds in 6m shed); Soil quality: preferably sandy loam; Build a shed: cover the bed with a small shed and prepare a sunshade net.
2. Sources of drilling cuttings
When used for cutting in autumn, the top with the same growth period and plant characteristics is the best. Winter and spring cuttings come from growing cuttings.
3. Cutting time,
Stevia rebaudiana can be cut all year round, with the best cutting in September-June at 65438+ 10. The cuttings are directly cut from the stems and branches growing in the field, and are mainly used for transplanting in early spring, with high yield and excellent quality. The seedlings cut in autumn can also be cut again to expand reproduction during the winter in greenhouse. As long as the seedlings grow to more than 5 pairs of leaves, 3-4 leaves can be pinched for reproduction.
4. Cutting method
After preparing the seedbed, water it the night before cutting and plant it the next day. Stevia cuttings should be cut together with the cuttings, and a pair of leaves should be buried in the soil. When cutting, shading with sunshade net is beneficial to rapid rooting and survival.
5. Cutting density
Plant spacing 1.5cm, row spacing 3cm.
6, cutting seedling management
When cutting in autumn, winter and early spring, keep the air humidity in the film high and the temperature appropriate after cutting, remove the sunshade net after living the trees, and keep the temperature in the shed at around 25℃ during the day and above 10℃ at night. When the temperature in the shed exceeds 30℃, open the shed mold and make good ventilation. In autumn, the cuttings are fertilized once during wintering and once before transplanting. Seedlings cut in winter can be fertilized according to seedling conditions. Choose a sunny morning, lightly water with decomposed fine water fertilizer, and spray water to wash the leaves in time to prevent the fertilizer from damaging the burnt leaves.
Third, transplantation and management.
1, specifications of transplanted seedlings
Stevia seedlings grow to 3? When the leaves are paired, the young roots have strong absorption ability and the growth gradually changes from slow to fast. Where is a 4? Five pairs of Stevia rebaudiana seedlings with true leaves and plant height above 10 cm can be used as transplanted seedlings.
2. Selection of transplant site
It needs fertile and loose soil and good drainage system. Don't plant low-lying land and poorly drained fields to prevent water accumulation or waterlogging in the fields.
3. Land consolidation and border preparation
The distribution depth of Stevia rebaudiana root system in the field is about 20-25 cm, and proper deep tillage is beneficial to the full extension of root system and the healthy growth of plants. Stevia rebaudiana transplanted seedlings are small, and the soil preparation requirements are fine, which is convenient for planting live trees.
Idle fields in winter, deep ploughing in autumn and winter to promote soil maturation, ploughing and raking to level soil moisture after thawing in spring, and furrowing to build the border. Early-maturing crops should be planted in summer.
Step 4 raise seedlings
One day before transplanting stevia seedlings, the seedbed should be watered first to make the soil soft and easy to carry. Seedling raising should try to avoid damaging the root system, keep the leaves moist and plant with the seeds.
Step 5 transplant properly
Planting Stevia rebaudiana early in time can prolong the vegetative growth period and increase the yield. Transplanting autumn seedlings, transplanting winter seedlings, and early planting of overwintering seedlings with old roots. Spring transplanting seedlings are suitable for transplanting after wheat oil.
Transplanting time: When the daily average temperature is stable at 65,438+02-65,438+05℃ and the ground temperature is above 65,438+00℃, the plastic-mulched plants can be transplanted on March 20-25, and those in the open field are generally around April 20, and they need to be transplanted suddenly before and after the rain. It is best to transplant before 10 in the morning and after 3 pm on sunny days, and transplant all day on cloudy days. Plastic film mulching should also pay attention to temperature changes. The highest temperature in the membrane does not exceed 30℃. After April 25th, all the films were unveiled.
6. Reasonable close planting
The plot width is 2m, and each plot has 4-5 rows. It is appropriate to transplant 8000 plants per mu of blank stubble covered with plastic film, and transplant blank stubble in the open field per mu 10000 plants. After planting wheat oil, the density can be increased appropriately. The row spacing of transplanted plants in blank stubble field is 15? 20 cm, row spacing 45-50 cm.
7. Tian Tuan management
(1) Rational fertilization
Base fertilizer. Generally, 50 tons of ash mixed fertilizer or 75- 100 kg of cake fertilizer is applied per mu, and 50 kg of 45% potassium sulfate ternary compound fertilizer is added per mu. The cake fertilizer should be fermented and decomposed in advance and applied in strips together with compound fertilizer.
Seedling fertilizer. After the first coring, topdressing 5-7.5 kg urea per mu.
Top dressing After coring for the second time, take out the branches and top dressing before closing the field, with 5-7.5 kg urea per mu.
(2) Water the living trees. Water the living trees in time after planting. According to the weather conditions, it is generally necessary to water continuously for 2-3 days, and the watering time should be controlled before 9: 00 a.m. to keep the soil moist for survival within one week.
(3) intertillage weeding. Before transplanting, use soil sealing agent (Jinduer) for sealing treatment. Weeding and intertillage should be done in time according to the growth of weeds before sealing the line. After sealing (seedling height 50? 60 cm) stop intertillage and mow instead.
(4) removing vertices. Stevia seedlings grow to 5? 7 pairs of true leaves, you can pick the heart for the first time. Cored for the second time, when the branches grow to 5-7 pairs of leaves, the top of the branched seedlings can be removed. The purpose of enucleation is to promote more branches and leaves. If the core is removed too late, the branches will be high, forming high seedlings, which are easy to fall and break, resulting in reduced production.
Fourth, pest control.
Seedling sheath blight can be sprayed with 50% thiophanate methyl solution every 7- 1000 days; In the late stage of production, leaf spot should be sprayed with 50% zineb 1000 times solution or 50% Tobezin 1000 times solution at the beginning of the next leaf. 65% zineb can be sprayed 500-600 times after the onset of black spot disease. At the same time, we should do a good job in the prevention and control of underground pests and aphids such as crickets, ground tigers and grubs.
Verb (abbreviation for verb) leaves picking and storing.
1, suitable for harvesting
Timely harvesting is one of the key technical measures to ensure the glycoside content of stevia rebaudiana leaves. When the plants began to sprout, the glycoside content of stevia rebaudiana leaves was the highest, and 50% of the plants in the field population sprouted as the standard harvest time. Harvest should be done after the dew dries on a sunny day. If the planting area of farmers is large and it is too late to harvest and wipe leaves, growth promoters should be sprayed in batches to delay the budding stage, so as to facilitate the timely picking of leaves. The accumulation of nutrients in stevia rebaudiana leaves is related to the temperature at that time. When the average temperature is lower than 20℃, the accumulation of sweet substances decreases, so the second cut leaves should be harvested before the end of September.
2. Harvest site
One or two crops can harvest stevia respectively, and the harvested stevia is cut from the part with green leaves; If you harvest the second crop, you should pay attention to the harvesting position to ensure the regeneration of the harvested plants. Keep 1 on plants? Suitable for green leaves. When harvesting stevia rebaudiana, you should try to avoid trampling on stubble plants to avoid plant death.
3. Harvest method
Harvesting a field with two blades In order to prevent the root system from loosening during harvesting and causing plant death after harvesting, it is best to trim the harvest with sharp scissors. The harvested stems and leaves should be rain-proof, and should not be washed for a long time and piled too thick to avoid fever, browning and mildew.
4, defoliation and drying
Wipe the leaves off the stems and branches by hand, and the leaves must be dried in time. They can be dried in cement yards and bamboo curtains to make them thin, diligent and fast. The stevia leaf threshing floor should be cleaned every day and the surrounding area should be cleaned to avoid other impurities. Stevia rebaudiana leaves, if attached with sediment, should be removed by sieving. Sun-dried leaves should be packed into edible plastic bags as soon as possible (fertilizer bags and pesticide bags are prohibited), and the bag mouth should be tightly sealed and transported to the designated place for packaging in time. If there are any sun-dried leaves, be sure to spread them indoors to avoid excessive heat and mildew. Stevia rebaudiana leaves are not allowed to be mixed with chemical fertilizers, pesticides and other substances during storage and transportation.
5, quality requirements
The leaves are bright green, and the dry leaves reach the safe storage water content (less than 10%), that is, they are fragile by hand. No impurities, no sediment, no branches, no flowers, no seeds, no dead leaves, no black leaves, no mildew and deterioration.
Cultivation techniques of stevia rebaudiana
(1) Suitable soil conditions for production
The soil layer is deep and the structure is good. The topsoil is 20-40cm, the organic matter content in the topsoil is more than 1.2%, the total nitrogen is more than 0.09%, the alkali-hydrolyzable nitrogen is more than 70mg/kg, the available phosphorus is 20-35mg/kg, the available potassium is more than 130mg/kg, the soil PH value is about 7.0, and the trace elements are sufficient.
(2) Excellent transplantation
1, standard for transplanting seedlings
The seedling size of Stevia rebaudiana is closely related to the survival rate and growth recovery after transplantation. For example, if the seedling is too old, the root system will be easily damaged when it is started, which is not conducive to greening. Young seedlings, small roots, poor development and poor drought resistance. Therefore, it is necessary to master the seedling age when transplanting. When transplanting, the standard of seedling size is: 5-7 pairs of true leaves, 8- 12 cm in height and developed roots.
2. Apply plantar fertilizer before transplantation
According to research, stevia rebaudiana needs 5.0-6.0kg pure nitrogen, 0.0-2.0 kg phosphorus pentoxide and 6.0-8.0kg potassium oxide per 100kg dry leaves. Under the condition of medium and high soil fertility, the base fertilizer should generally be applied with more than 3000 kilograms of high-quality organic fertilizer per mu, or 20-30 kilograms of urea and 30-40 kilograms of compound fertilizer. At the same time, supplement trace elements.
3. Transplant time
Stevia rebaudiana is a warm-loving plant. Only when the daily average temperature is stable at 12- 15℃ and the ground temperature is above 10℃ and there is no danger of late frost can transplanting be carried out. Stevia rebaudiana planted in spring usually starts transplanting in late April; Sowing in summer, the earlier the wheat is harvested, the better.
4. Transplant density
Spring sowing, 6.5438 million plants per mu; 654.38+200,000 plants were planted in summer. Planting in large and small rows, with large row spacing of about 40 cm, small row spacing of 30 cm and plant spacing of 20 cm.
5. Transplantation technology
Seedlings should be planted in the morning and evening or on cloudy days to avoid being exposed to the sun after planting. When the seedlings are raised, the root system should be damaged as little as possible. When planting seedlings, the seedlings should be vertical to the ground, so as not to press the heart, hurt the bottom leaves and nest roots. After transplanting, root water should be poured, and then seedling water should be poured for 2-3 days to promote root growth. Transplanting operations should be carried out continuously, and all links of seedling raising, seedling planting and watering should be closely coordinated.
(3) Field vas deferens
1, check the seedlings and make up the seedlings
Check the seedlings of Stevia rebaudiana after transplanting and replenish them in time, otherwise the lack of seedlings and broken ridges will affect the yield.
Choose your heart at the right time
Stevia rebaudiana has the advantages of apical growth, and also has the ability of secondary growth and regenerative growth. In order to adjust and promote the branching habit of Stevia rebaudiana, promote the lush foliage and achieve high yield and high quality, topping (also called topping) must be carried out.
Tapping can promote the growth of lateral buds, increase the amount of branches and leaves, make plants shorter, prevent lodging in the later stage and improve yield. Stevia rebaudiana 7-9 pairs of true leaves were picked when the plant height was 15-20cm. The coring time should be carried out in sunny days, which is beneficial to wound healing.
3, intertillage weeding
Intertillage weeding can coordinate the relationship between Stevia rebaudiana and the environment and environmental factors in the field growth period, and create an ecological environment conducive to the growth of Stevia rebaudiana. Generally, the number of intertillage is 2-4 times, the first intertillage is about 10 days after the fixed value, and then every 10- 15 days, and the last intertillage is carried out before ridge closure. The depth of intertillage is based on the principle of not hurting roots. Weeding of gramineous weeds in seedling stage is carried out in 2 ~ 5 leaves, and 30 ~ 40 kg of water is sprayed evenly with 10.8% efficient covering energy EC 25 ~ 30ml/ mu.
4. Topdressing and watering
Generally, topdressing is carried out twice. After the first seedling delay, apply 20-30 kg urea or 20 kg compound fertilizer per mu, and urea 10 kg. For the second time, before closing the ridge, apply 30-40 kg of urea, 0/0-/0-5 kg of diammonium phosphate and 0/0-65438+of kloc per mu.
5, pest control
Pest control should be based on comprehensive control. Treat small early? The principle of. Under the premise of selecting excellent varieties, implementing crop rotation, strengthening fertilizer and water management and reasonable close planting, pay close attention to the occurrence of diseases and insect pests in the field, immediately remove the diseased plants when they are found, and carry out effective control combined with measures such as spraying drugs.
Planting conditions of stevia rebaudiana
Stevioside is a subtropical plant, which is suitable for growing in an environment with little initial frost, abundant rainfall, abundant sunshine and warm climate. Stevia rebaudiana includes more than 100 varieties, among which stevia rebaudiana leaves have the highest sweetness.