Mint. ) Also called Su Mint. It is a perennial herb of Labiatae. Mainly produced in Jiangsu, Jiangxi, Hebei, Sichuan and other provinces, and cultivated all over the country. Use whole grass as medicine. The content of volatile oil in the stems and leaves of mint is about 65438 0%. The volatile oil, called peppermint oil, mainly contains 77-87% L- menthol, followed by 65438 00% L- menthone and 3-6% menthyl ester, and also contains D-8- acetoxy carvone and Ai Ju ketone. Pungent in taste and cool in nature. It has the functions of dispelling wind, clearing heat, clearing head and penetrating rash. It can be used for treating wind-heat common cold, headache, red eyes and sore throat, aphtha, rubella, measles, etc. Menthol has analgesic, antipruritic, antiseptic and bactericidal effects, and can be made into preparations or medicines for oral administration or external use. In addition, it is also used in spices, food, cosmetics and other industries. , a wide range of uses, a large amount.

I. Morphological characteristics

The plant height is 30-80 cm, sometimes reaching 1m, and the whole plant has a cool fragrance. Rootstock creeping. Stems erect or decumbent at base, square, with retrorse puberulent and glandular points. The leaves are opposite, lanceolate, sometimes oval or oblong, 3-7 cm long and 2-3-7 cm wide, with serrated edges and fluffy yellow glandular spots on both sides. Inflorescence axillary; Calyx bell-shaped, covered with white pilose and glandular spots, 10 veins, 5 teeth; Corolla red-purple, 2-lipped, upper lip 2-cleft, lower lip 3-cleft; Stamens 4; Ovary 4-lobed; Style inserted at the bottom of ovary. Four nutlets are ovoid and hidden in persistent calyx (Figure 16-40).

Fig.16-40 mint morphological diagram.

1. Lower part of valve stem 2. Upper part of valve stem 3. Flowers 4. Calyx spreading 5. Corolla spreading shows stamens and pistils.

Second, biological characteristics.

(1) growth and development

The underground part of mint includes rhizome and root. Roots occur at the base of the mint stem. Under suitable temperature and humidity conditions, these new roots will sprout and appear. Peppermint seedlings grow to a certain stage and grow new roots. Rootstocks have no dormancy period. As long as the environmental conditions are suitable, it can germinate and grow into plants all year round. Used as breeding material in production. Roots are very shallow in the soil, and most of them are concentrated in the soil surface layer 15cm, with a horizontal distribution of about 30cm. There are also fibrous roots and aerial roots on the roots and stems of mint. Fibrous roots are concentrated in the soil layer of 15-20 cm, which is the main organ for mint to absorb water and nutrients.

The aerial part of mint has erect stems, stolons and leaves. Axillary buds on erect stems germinate into branches.

Buds on the basal nodes of stems can germinate into stolons that grow horizontally along the ground. After the first or second harvest of mint, the buds on the stem nodes or stolons can germinate into new seedlings and branch upward because of changing the top growth advantage of the plants.

There are oil glands on the leaves of mint, which are distributed in the upper and lower epidermis, and the lower epidermis is the most, which is the place to store volatile oil. The density of oil glands on leaves is related to oil content. The yield and oil content of mint are closely related to varieties, environmental conditions, cultivation techniques and harvest time. When the plant grows to a certain period, it begins to sprout and blossom on the nodes of the erect stem, and with the continuous growth of the top of the stem, it forms cymes. Peppermint blooms once a year, and the flowering period varies with varieties and regions. Generally, the flowering period is August -65438+ 10, and the fruiting period is September-165438+ 10.

(2) Environmental conditions for growth and development

Peppermint is native to the north temperate zone and has strong adaptability to environmental conditions. It can grow in areas below 2 100 meters above sea level. However, when cultivated at low altitude, the content of essential oil and menthol is higher. I like warm and humid environment. Roots germinate and emerge at 5-6℃. The suitable temperature for plant growth is 20-30℃. When the temperature is -2℃, the stems and leaves wither. However, the roots of mint have strong cold tolerance, so long as the soil keeps a certain humidity, it can still safely overwinter in the area of -30-20℃ in winter. Generally speaking, in the case of large temperature difference between day and night, mint is beneficial to the accumulation of oil and brain. Light is of great significance to the yield and oil brain content of mint. Long sunshine can promote flowering and increase oil content. Therefore, sufficient sunshine during growth is beneficial to the accumulation of oil and brain. Insufficient light or shade is not good for mint growth. Rainfall distribution has a great influence on the growth and development of mint. Plants need more water in the early and middle stages of growth, and sunny and dry environmental conditions are needed in the germination and flowering stages. Peppermint is not strict with soil. Generally, it is better to plant in fertile loam. If it is too barren and the drainage is not smooth, it will grow badly. Suitable soil pH is 5.5-6.5, and soil with pH7.5 can also be cultivated.

Second, the cultivation techniques

(1) variety

Due to long-term breeding and cultivation, mint has formed many cultivated varieties. Such as purple stems and purple veins, green stems and round leaves, purple stems and white veins, green stems and pointed leaves, green stems and leaflets, 68-7 mint, borneol mint and so on. At present, Jiangsu, Zhejiang and other places mainly plant two kinds of mint: green stems, round leaves and purple stems and purple veins.

1. Green-stemmed round-leaf species

The upper part of the stem is cyan, the leaves are short, oval and shiny, and the plant is short and branched, with a brain content of about 80%. Planting on fertile land has more obvious high-yield characteristics and is one of the excellent varieties in cultivation.

2. Purple stem purple vein species

The stem of the plant is dark purple, the leaves are rectangular, the serrations are sharp and dense, and there are few branches. The yield is slightly lower than that of the green stem round leaf species, but the oil brain content is 2-5% higher, and it is also a famous good species.

Recently, Shanghai Institute of Spice Industry Science cultivated a high-yield mint variety 73-8 with many branches, short internodes, large leaves and dense glandular scales. The oil yield of fresh grass is 0.3-0.5 1%, the oil yield per mu is 9.75- 15.22 kg, and the brain content is 80. 13-. It has been widely planted in mint producing areas.

(2) Breeding methods

There are seed propagation, cutting propagation, branch propagation and rhizome propagation. In production, rhizome propagation method is generally used. The late October of 165438 to the early October of165438 is the planting period of mint. When planting, the roots should be planted with digging. After digging out the underground rhizome, choose the rhizome with short internode, white color, strong and no pests and diseases as the seed. Then, a ditch with a row spacing of 25cm and a depth of about 6- 10 cm was opened on the planting land with sufficient base fertilizer and intensive cultivation, and the seed rhizomes were scattered into the ditch. The seed rhizome can be discharged as a whole, or it can be cut into small pieces 6- 10 cm long and scattered. Planting density should be connected with the root end to end. Cover the soil immediately after planting, rake it flat and compact it. The amount of seed used per mu depends on the quality of seed rhizome. Generally, 75- 100 kg of tender new rhizome is needed.

(3) Site management

In addition to intertillage weeding, keeping the countryside clean and tidy, paying attention to dredging ditches, preventing water accumulation after rain, irrigation in time, keeping the humidity in the field, and the most important thing is topdressing. Mint is harvested several times a year, and it needs to be fully applied with base fertilizer and reasonable topdressing to meet the needs of plant growth again. Generally, mint is topdressed for 4 times, and the fertilization time is: after full seedling (April); Peak growth period (May-June); After harvesting the first mint (July), when the height of the second mint seedling is about 15cm (late August). The main fertilizer is nitrogen fertilizer, supplemented by phosphorus and potassium fertilizer. Topdressing 1, 4 times is slightly lighter, and 2 or 3 times is heavier. Light users use 20 loads of manure per mu and water it; Or 20 kilograms of ammonium bicarbonate per mu. When applying again, 30 tons of concentrated fertilizer, 50 kg of cake fertilizer or 25 kg of ammonium bicarbonate are used per mu.

(4) diseases and their prevention and control

1. rust

Puccinia mentholata. )

In the early stage of the disease, there were orange powdery summer spore piles on the back of leaves, and black brown powdery winter spore piles were produced in the later stage. In severe cases, the leaves will die and fall off. The rainy and humid season in May is conducive to the occurrence of this disease. Prevention and control methods: eliminate water in the field in time to reduce humidity; Spraying 25% triamcinolone acetonide 1000 times solution at the initial stage of onset.

2. White Star Disease

(Septoria menthicola Sacc.et Let。 )

Also known as leaf blight, it occurred from May to 65438+ 10. At the early stage of the disease, nearly round dark green spots appeared on both sides of the leaves. Subsequently, the nearly round or irregular dark brown lesions continued to expand. In the later stage, the interior of the lesion faded to grayish white, showing a white star shape with black spots (pathogen conidia). In severe cases, the leaves will die and fall off. Prevention and treatment: spray 50% carbendazim 1000 times solution or 1: 1: 200 bordeaux solution alternately at the initial stage of onset. Stop spraying 20 days before harvesting.

(5) keep the seeds.

Mint goes bad easily, so pay attention to seed selection. There are two ways to select and keep improved varieties: on-site seed reservation and transplanting seed reservation.

1. Sow in situ

When the height of mint seedlings is 15cm in late April or 15cm in late August, select a well-bred mint field with vigorous growth, combine with weeding, uproot wild species and other hybrids in two steps, and pull out weak seedlings with poor growth as reserved land.

2. Transplant and preserve seeds.

In late April, healthy and non-degenerate plants were selected in the field and transplanted into another field according to the row spacing of 15cm to strengthen the management of seed use.

Fourth, harvesting and processing.

(1) Harvest

In Jiangsu and Zhejiang provinces, mint is harvested twice a year. Harvest in North China 1-2 times a year; Sichuan can receive 2-4 times. The first harvest in Jiangsu province was in July, which was called the first knife; The second time was in 10 month, weighing two knives and picking on sunny days. The collected mint can be used as medicinal materials.

(2) Processing

Spread the harvested mint in the sun for two days, turn it over, dry it a little, and tie it into small sticks. When tying, align the stems, then remove the leafless stems 3-5 cm below the leaves, and then dry them in the sun or in the shade. After the stems and leaves of peppermint are dried in the sun, they can be put into a distillation pot in batches for distillation to obtain volatile oil, namely peppermint oil.