Direct seeding cultivation techniques of Glycyrrhiza uralensis in Hexi Arid area

Licorice is the most commonly used bulk Chinese medicine and is known as the king of medicine. The current cultivated species is Glycyrrhiza uralensis, which belongs to the genus Glycyrrhiza uralensis. It has strong water-saving, drought and cold tolerance. It is an excellent wind-proof and sand-fixing vegetation in arid and semi-arid desert areas. The medicinal part is dry root, which not only has the effects of tonifying spleen and qi, relieving cough and expectorant, clearing heat and detoxification, reconciling medicinal properties, but also widely used in daily necessities, light industry, animal husbandry and food industry.

Minqin County, located on the edge of Badain Jaran Desert and Tengger Desert, is one of the main producing areas of cultivated licorice in Gansu Province. in recent years, due to over-mining, wild licorice resources have decreased sharply and have become one of the endangered species. The county has a small population and more land, with a large area of wasteland, abandoned farmland and saline land, which can be used for artificial cultivation of licorice. In addition, with the advantages of Shiyang River irrigation, rich light, long sunshine, fertile soil and large temperature difference between day and night, it is not only the most suitable area for Gansu licorice planting, but also the largest artificial licorice cultivation base. The main techniques of local artificial cultivation of licorice are direct seeding and transplanting, and the direct seeding cultivation techniques are summarized as follows.

1 selection and preparation of land

1.1 Glycyrrhiza uralensis is a perennial herb with developed root system, deep soil penetration, light tolerance, drought tolerance, salt tolerance and fear of stagnant water. it is suitable to grow in sandy land, grassland, riparian and desert and semi-desert environment. Therefore, the cultivation of licorice should choose sandy loam with low groundwater level, good drainage, slightly alkaline soil, deep soil layer and convenient irrigation.

1.2 the land planted with licorice in fine soil preparation had better be ploughed once in the autumn of the previous year, and the tillage depth was not less than 35cm. Before sowing in spring, the soil was deeply ploughed and prepared into a small bed of 200 square meters and 300 square meters.

2 seed treatment

2.1 the seeds of Glycyrrhiza uralensis are selected, which are full, uniform, moth-free, purity above 90% and 1000-grain weight about 10-12 g.

2.2 the hardness of licorice seeds treated by licorice is 92%-98%, the seed coat is smooth and dense, the water is difficult to penetrate, and the germination rate is very low. It must be treated before sowing. The best method is to treat the seeds with concentrated sulfuric acid: put the seeds to be cleaned in an acid-resistant container, add 80% concentrated sulfuric acid 2500~3000ml to each 100kg seed, stir quickly and place for about 1 hour, stop the treatment when acid corrosion black spots appear on the seed coat, rinse all the seeds with clean water for many times, sow or dry immediately, the germination rate can reach about 90%.

3 sowing

3.1 the suitable germination temperature of licorice seeds during sowing period is 20-25 ℃, and it is generally the most suitable for sowing in the middle and late April.

3.2 the sowing method of licorice generally includes strip sowing, hole sowing and on-demand sowing. The way to sow seeds should be determined according to the site type of the planting site. If the terrain is flat, the plot area is large, and it is convenient for mechanical operation, the seeder is used to sow seedlings evenly, it is convenient for intermediate ploughing and weeding, the row spacing is 25cm, and the depth is 2.0~2.5cm. Fill the "seat water" 3-4 days before sowing, and cover the soil in time to protect soil moisture after sowing. For plots with complex topography and large ups and downs, hole sowing and on-demand are suitable.

3.3.The sowing rate is 300 ~ 375000 plants per hectare, and the planting amount of licorice strip sowing is 30~45kg/ ha.

4Fertilizer and water management

4.1 Glycyrrhiza uralensis is sensitive to phosphorus and potassium in soil, and more phosphorus and potassium fertilizers should be applied in fertilization.

4.2 the application of sufficient base fertilizer is generally combined with deep ploughing with diammonium phosphate 375~450kg/ ha, zinc mixed fertilizer 600kg/ ha and potash fertilizer 150kg/ ha as base fertilizer before sowing. Conditional application of 45000g/ ha ripening farm manure has a better effect.

Reasonable topdressing of licorice is generally not topdressing at seedling stage, but urea 120~150kg/ hectare is applied in combination with irrigation at branching stage to facilitate stem and leaf growth. Biennial licorice has entered the fast-growing period. In order to avoid the effect of fertilizer removal on yield, diammonium phosphate (DAP) per hectare of 300kg/ should be applied. Topdressing should be combined with mid-tillage, weeding and ditching and burying into both sides of the root system.

4.4 timely irrigation licorice should be filled with sufficient bottom water before sowing. The seedlings were irrigated for 2 to 3 times during the growing period, the first time at the 7~10cm of seedling height and the second time at the branching stage. In the future, we should timely master irrigation according to the drought. Direct seeding licorice is irrigated for 2 or 3 times in the second and third years, and licorice that has been irrigated with winter water is generally irrigated for the first time in the branching period; if the summer high temperature season, licorice stems and leaves appear obvious defoliation phenomenon, which can be irrigated for the second time; irrigation should be carried out timely from mid-August to early September, so it is the best time for licorice to accumulate active components and the key time for licorice to gain weight.

4.5 Winter water irrigation is best arranged from the first ten days of December to January of the following year.

During the growth period of licorice, spraying plant growth regulators such as Aiduoshou and Plant Power 2003 had a certain effect on the yield of Glycyrrhiza uralensis.

Five seedlings are fixed

When the seedlings of Glycyrrhiza uralensis seedlings grow to 15cm height, the distance between seedlings can be 10~15cm, and the seedlings can be preserved about 330000 plants per hectare.

6. Ploughing and weeding

6.1 herbicide Glycyrrhiza uralensis can be used to control weeds if Gramineae weeds appear after emergence, and glyphosate can be used to remove weeds in time if wheatgrass, Reed grass and other weeds appear. The effect is best when the weeds have 3 or 6 true leaves.

6.2 Intermediate ploughing and weeding is the main management link to increase the yield of licorice, and intertillage should be carried out after each irrigation. The weeding of Glycyrrhiza uralensis requires early hoe, small hoe and hoe.

(7) Disease and pest control

Licorice pest is mainly licorice leaf beetle, and the best time to control the insect is the harmful period of overwintering adults and first-generation larvae. when there is a small insect feeding gap in licorice leaves, it can be controlled by 1500 times of omethoate EC or 6000 times of 2.5% dimethoate EC.

Licorice diseases are mainly licorice brown spot, rust and so on. When sowing, it is best to treat the seeds with wettable carbendazim, methyl thiophanate and other agents, according to the effective concentration of 0.5%-1% of the seed dosage. After dressing, the seeds can be sown for 1 h. 50% carbendazim can also be used to treat the soil; if licorice rust or brown spot occurs, the licorice disease plant can be partially removed and buried deep outside the licorice field; 20% verapamil EC or 95% diazepam sodium solution can be used to control rust twice in a row. 70% methyl topiramate is used to control brown spot.