Virus-free strawberry shoot tips

Strawberry "shoot tip seedling" refers to the tissue culture seedling formed by shoot tip in test tube. Shoot tip culture can remove germs and rejuvenate seedlings. "Shoot-tip seedlings" can also produce more stolons for seedling propagation than conventional seedlings.

"Shoot tip" usually includes growing point and 1-2 Yuan Ye group, about 0.4-0.5 mm ... The following figure shows a standard strawberry shoot tip.

The suitable stolon state is: 1-3 spreading leaves (below). The cutting of stem tip is completed under stereomicroscope.

Medium:

Shoot tip culture "improved DKW+30g/L glucose+Ba0.1mg/L+IBA0.01mg/L+agar, 2 1-24℃".

The amplification medium "BD 1+40g/L glucose+ba0.5mg/l+iba0.5mg/l+PVP 0.1g/l+agar, 25-30℃". Rooting medium "BX 1+40g/L glucose+IBA1mg/l PVP 0.1g/l+activated carbon 0.5g/L". Remarks: There are many kinds of media for strawberry shoot tip culture and tissue culture seedling propagation, which can be adjusted according to the actual situation.

Shoot tip culture is generally completed in test tubes and lasts for 3-5 months. The process of shoot tip seedling raising is as follows.

Virus detection

Five viruses (ARMV, RRSV, SLRV, TBRV and Smiev * * *) were detected by enzyme-linked immunosorbent assay (French standard). Virus detection can also be done by PCR.

Key points of quality control

(1) Shoot-tip seedlings were most amplified by tissue culture 10 generation.

(2) Use low concentration of barium, not exceeding 0.5 mg/L. ..

(3) Microbial culture medium can be used to screen bacterial and fungal pollution in the early stage of shoot tip culture.

General situation of strawberry

Herbs perennial, 10-40 cm tall. Stems below leaves or subequal, densely spreading yellow pilose. Leaves trifoliolate, short petiole, thick texture, obovate or rhombic, sparse and round, 3-7 cm long and 2-6 cm wide, blunt at the top, wide wedge at the base, oblique at the base of lateral leaflets, serrated at the edge, extremely sharp at the top, dark green at the bottom, sparse at the bottom, and dense along veins; Petiole 2- 10 cm long, densely yellow pilose.

Geographical distribution of strawberries

Native to South America, it is widely cultivated in China and Europe. ?

Nutritional value of strawberry

Strawberry is known as the "fruit queen" because of its rich nutritional value. It is rich in vitamin C, vitamin A, vitamin E, vitamin PP, vitamin B 1, vitamin B2, carotene, tannic acid, aspartic acid, copper, strawberry amine, pectin, cellulose, folic acid, iron, calcium, ellagic acid and anthocyanin.

Especially the content of vitamin C is 7- 10 times higher than that of apples and grapes. The contents of malic acid, citric acid, vitamin B 1, vitamin B2, carotene, calcium, phosphorus and iron are also three to four times higher than those of apples, pears and grapes. ?

Strawberry is rich in carotene and vitamin A, which can relieve night blindness, maintain epithelial health, improve vision, nourish liver and promote growth and development. Strawberry is also rich in dietary fiber, which can promote the peristalsis of gastrointestinal tract, promote the digestion of food in gastrointestinal tract, improve constipation and prevent acne and intestinal cancer.

Traditional propagation method of strawberry

seed

Seed propagation is mostly used for long-distance introduction or cultivation of strawberry seedlings to select new varieties, and it can also be used for dual-purpose planting in courtyard greening. When fruits are harvested in May and June, well-developed and fully mature fruits are selected for seed collection. Peel off the peel, put it in water, wash off the slurry, and take it out to dry; Or directly air-dry the peeled skin, and then crush it to separate the skin from the seeds.

Seeding and seedling raising are mostly carried out in the spring of the following year, but they can also be carried out in July-August of the year of seed collection. Before sowing, prepare a wide-mouth pottery jar, fill it with fine nutrient soil, flatten it, soak the seeds 8- 12 hours in advance, spread it on the soil surface after expansion, and then cover it with fine sand with a sieve about 0.2 cm thick. In order to keep enough moisture in the soil and keep it loose, which is beneficial for the seeds to take root and sprout, the sowed clay earthen basin can be put into a shallow pool, taken out after the water slowly penetrates into the soil in the basin, covered with plastic film, and the seedlings can emerge in about 10 days.

After emergence, properly space the seedlings, and when the seedlings grow 3-4 true leaves, transplant them into small flowerpots with soil. After a period of adaptation, transplant to a breeding nursery with soil. ?

Factory division

There are two kinds of ramet propagation, one is rhizome ramet and the other is new stem ramet.

Rhizome ramet

After the fruit is harvested, the management of mother plants should be strengthened in time, such as fertilization, watering, weeding and loosening the soil. It should be carried out in time to promote the axillary buds of new stems to grow new stems. When some new leaves are extracted from the aboveground part of the mother plant and new roots grow from the underground roots, the old roots are dug out, the black adventitious roots and aged rhizomes at the lower part are cut off, and the new rhizomes are separated one by one. These roots have 5-8 thick leaves, and there should be 4-5 vigorous beige adventitious roots in the lower part. The separated rhizome can be directly planted in the production garden. Water strawberries in time after planting, strengthen the management of strawberry planting, promote their growth, and make them bear normal fruits in the next year.

New stem ramet

In addition to the method of rhizome and stem division, new stem seedlings of mother plants can also be cultivated. The method is: after the fruit is harvested, the plants that bear fruit in the first year are dug out with clods and replanted in the flat bed. The border is 70 cm wide and can be planted in two rows with a row spacing of 30 cm. Dig a pit every 50 cm in each row and plant two seedlings in each pit. A month later, the mother plant sends out stolons, and when each plant has 2-3 stolons, the stem tip is pinched off to thicken the new stem seedlings on the mother plant. The removal of stolons should be repeated. For the 2-year-old seedlings planted in this way, at least 4-6 new stem seedlings can be separated from each hole. The inflorescences planted on the new stem, together with the inflorescences on the stolons around the new stem seedlings, are more 1/3 than those planted only on stolons, and the yield is also significantly improved, and the land and labor of seedlings are also saved. After the fruit is harvested, the 3-year-old strawberry seedlings are removed, and the 2-year-old seedlings with 1 year fruit can still be used. ?

Tissue culture of strawberry

Why should strawberries be detoxified?

Strawberries often provide seedlings for production through asexual reproduction. The traditional stolon propagation is slow, which can't keep the excellent characters of parents, and the quality of strawberries decreases. However, long-term use of asexual propagation seedlings will easily lead to variety degradation, serious virus accumulation, weakened disease resistance, short strawberry plants, withered roots, less fruits, more deformed fruits, and a sharp decline in yield, quality and benefit, which has become an urgent problem in production.

Advantages of strawberry virus-free

Virus-free strawberry is to use tissue culture technology to detoxify explants (usually stem tips or pollen) of strawberry seedlings, and then carry out tissue culture and rapid propagation to expand the number. Tissue culture is the most economical and effective method for virus-free strawberry.

Virus-free strawberry and propagation of test-tube seedlings by plant tissue culture technology can shorten the propagation cycle of strawberry. The maximum propagation coefficient of virus-free seedlings can reach 70 ~ 120, and the propagation coefficient of common seedlings is about 30 ~ 40 under normal conditions. Its reproductive coefficient is 1.2 ~ 1.5 times higher than that of common seedlings.

Eliminate the virus content accumulated in the body, maintain the excellent characters of parents, greatly enhance the disease resistance, high temperature resistance or cold resistance of plants, and generally rarely use pesticides.

Compared with conventional seedling raising, tissue culture seedlings obtained by tissue culture propagation have the advantages of vigorous growth, high survival rate, high yield and good economic benefits, and can increase production by 30%~50%. Compared with the original virus-free seedlings, the virus-free seedlings can increase the yield by 900 ~ 1500 kg per mu, and the average yield can reach 3200 kg.

The fruit is bright in color, large in size, uniform in shape and good in appearance, and the maximum single fruit weight is 60-80g. ? There are many flowers per plant, the number of inflorescences and the fruit-setting rate increase by about 50% on average, and the fruiting period is long, and the flowers bloom while maturing. The fruiting period is generally extended by 20 ~ 25 days.

The propagation speed of tissue culture seedling raising method is fast. Within a year, a meristem can obtain tens of thousands or even hundreds of thousands of seedlings, and it does not occupy land and is not affected by the environment, which is suitable for industrial production.

Breeding system of virus-free strawberry seedlings

The three-level seedling breeding system of strawberry refers to the three-level seedling breeding system of strawberry original seedling, original seedling and production seedling. In order to ensure the stability of virus-free seedlings, four-grade strawberries were gradually formed.

Acquisition of original seedlings

Firstly, the cut strawberry buds were heat-treated, then the apical growth point of meristem was cut by 0.2 mm under aseptic conditions, and the test-tube seedlings were cultured in suitable medium. After repeated virus identification, the obtained test-tube seedlings can be confirmed to be virus-free, so as to accelerate the propagation of a large number of test-tube seedlings and further propagate the original seeds for production.

Original seed production

Because the number of virus-free tissue culture seedlings cultivated in the laboratory is limited and the cost is high, it is necessary to further expand the propagation and produce the original seedlings.

In order to prevent the virus from being reinfected, strict isolation measures must be taken when expanding reproduction. If it is impossible to continue multiple cropping or the previous crop is solanaceae, Miao Di should use Mianlong or cobalt chloride for disinfection. Plant in March and April, and the original seedlings will be produced in September. At the same time, the growth and fruiting of strawberries were observed during the planting process to detect whether they met the conditions of virus-free seedlings.

seedling

In order to ensure the stability of strawberry seedlings, the original seedlings should be planted twice, pests and diseases should be prevented in time during the growth period, water and fertilizer management should be paid attention to, and the chance of strawberry reinfection should be reduced, and the growth status and various characters of strawberries should be observed to obtain high-quality strawberry seedlings for strawberry seedling farmers to breed and produce seedlings.

Produce seedlings

The breeding of production seedlings should be planted in soil rich in organic matter, and management should be in place. After one year's cultivation, the plants that meet the relevant quality requirements are production seedlings.

The main varieties of strawberries

There are many varieties of strawberries cultivated in China, and there are more than 20,000 varieties in the world, but there are only dozens of excellent varieties cultivated in a large area. There are 200-300 new varieties cultivated by China itself and introduced from abroad. The main cultivated varieties in production are as follows:

Shuofeng

Suitable for open cultivation in the middle and lower reaches of the Yangtze River. ?

Mingjing

Suitable for open cultivation in Northeast China and North China. ?

Ming Xu

It is suitable for open cultivation in northern areas such as Liaoning Province and close planting, with about 6.5438+0.2 million plants per mu. ?

Xu Chun

Suitable facilities promote cultivation. ?

Xing du Hao

Du Xing 1 Strawberry has a deep red flesh, which is suitable for fresh food processing, quick-frozen juice making and sauce making. It is a strain with early maturity, big fruit, high quality fruit hardness and storage and transportation resistance, which is suitable for semi-popularization cultivation.

Du Xing No.2 strawberry is a new strawberry strain with early maturity, big fruit, high yield, high fruit hardness and storage and transportation resistance. ?

Shibei 1

Good high-yield performance, average yield of 334.6g, few deformed fruits, good stress resistance, storage and transportation resistance, strong disease resistance and short dormancy period, so it is an excellent early-maturing variety. Suitable for fresh food and processing, and can be cultivated in the open field or protective arch shed.

Growth habit of strawberry

Strawberries like warm and cool climate. The growth temperature of strawberry root system is 5-30℃, the optimum temperature is 15-22℃, the optimum temperature of stem and leaf growth is 20-30℃, the freezing temperature of flower bud is-10℃, and the temperature of flower bud differentiation must be kept at 5-15. Strawberry in summer, when the temperature is higher than 30℃ and the sunshine is strong, shading measures should be taken.

Strawberry is a light-loving plant, but it has strong shade tolerance. Under the light intensity, the plant is short and strong, the fruit is small, the color is dark and the quality is good. Medium light, large fruit, light color, low sugar content and long harvest period; Weak light is bad for strawberry growth.

Strawberry has shallow root distribution, large transpiration and strict requirements for water, but its growth stages are different. Strawberries have slightly different water requirements. In early spring and flowering period, strawberry needs less than 70% of the maximum soil water content. The demand for fruit growth and ripening is the highest, reaching more than 80%. After harvesting, stolons and new adventitious roots should be removed, and the soil moisture content should be not less than 70%. Autumn is the period of plant accumulation and flower bud formation, and the soil water content should not be lower than 60%. Strawberries are not resistant to waterlogging, so the soil should be permeable. Pay attention to the site drainage in rainy season.

Strawberries should be planted in fertile, loose, neutral or slightly acidic loam. Too sticky soil is not suitable for cultivation. Strawberries can also be planted on sandy soil with more fertilizer and regular irrigation. ?

Cultivation techniques of strawberry

Land selection

Strawberry fields should choose fertile land with slightly higher terrain, flat ground, convenient irrigation and drainage, good illumination, rich organic matter, strong water retention, good ventilation and weak acid or neutral PH value. Previous crops were vegetables, beans, melons and wheat.

Weeds should be thoroughly removed before strawberry planting, and decomposed farm manure should be applied. Generally, 5000 kg of organic fertilizer, 50 kg of calcium superphosphate and 50 kg of potassium chloride are applied per mu as base fertilizer. After uniform application, the soil should be turned over for 30-40 cm to promote soil maturation. After the land is leveled, the boundary shall be made according to 100 cm, with a width of 80 cm and a width of the boundary ditch. ?

Field planting

When planting strawberries, attention should be paid to directional transplanting, and the seedling bow should be turned to one side of the channel so that the inflorescences can be planted in the same direction, and the number of plants should be one plant per hole. It is not advisable to bury the heart above the planting depth and expose the roots below.

Reasonable close planting: The planting density of strawberries has a great relationship with the planting level. Fields with weak seedlings, late sowing and lack of fertilizer should be densely planted with a planting density of about 8000 plants per mu. On the contrary, for the techniques of strong seedlings, early planting, full fertilization and plastic film mulching, it is appropriate to plant them thinly, with 6000 plants per mu and a row spacing of 50 cm× 20 cm. ?

water

Water it once after planting, usually once in the morning and evening within one week after planting, and then keep the soil moist frequently for survival. ?

Fertilize soil or land

Strawberries need more fertilizer from planting to flowering and fruiting. In addition to adequate base fertilizer, it is also necessary to replenish fertilizer in time. Strawberry special fertilizer or diammonium phosphate 10 kg can be applied at the fruit expansion stage and the initial harvest stage. Combined with watering, the effect of applying 200 times liquid fertilizer in ditch is better. Spraying 0. 1-0.2% potassium dihydrogen phosphate only for 2-3 times in the field with good growth also has certain yield-increasing effect. In principle, it is not sprayed during flowering. The principle of fertilization in fruit picking field is to apply nitrogen, phosphorus and potassium, and a reasonable proportion relationship must be maintained in order to obtain higher yield and maximum benefit. ?

involve

Plastic film mulching has obvious effect of early maturity and yield increase, and can also improve fruit quality and commercial fruit rate. Generally, film mulching begins in the middle and late March. Pay attention to dead leaves and old leaves on plants before covering with plastic film. ?

Tiantuan management

1, often remove diseased leaves, dead leaves and diseased fruits, take them out of strawberry fields and bury them deeply to reduce pests and diseases.

2, often remove the new stems.

3. Combined with harvesting, it is found that there are half red (sunny) and half blue fruits, which can be turned over to promote their uniform maturity.

4. Regularly clear ditches and manage soil moisture, so as to avoid water accumulation after rain, reduce field humidity and reduce diseased fruits and rotten fruits. ?

Strawberry pest control

leaf spot

Symptoms: Leaf spot, also known as snake eye disease, mainly harms leaves, petioles, fruit stalks, tender stems and seeds. Dark purple spots are formed on the leaves, and after expansion, a nearly round or oval lesion is formed, with purple-red and brown edges, gray-white center and slightly thin wheels, which makes the whole lesion snake-eyed, and no small black particles are formed on the lesion.

Prevention and control: remove diseased leaves and old leaves in time. 70% chlorothalonil wettable powder was used 500 -700 times at the beginning of the disease, and sprayed again ten days later. Or spray 75 kilograms of 70% mancozeb wettable powder with 200 grams per mu. ?

powdery mildew

Powdery mildew mainly harms leaves, flowers, fruits, fruit stalks and petioles. Leaves roll up like spoons. Buds and petals are purple, unable to bloom or fully bloom, and the fruit is not swollen and slender; The young fruit loses its luster and hardens. If the strawberry is damaged near maturity, it will lose its commodity value.

Prevention and treatment: In the center of the disease and its surrounding areas, Bubomei 0.3-degree stone sulfur mixture is mainly sprayed. After harvesting, cut leaves in the whole garden and spray 70% thiophanate methyl 1000 times solution or 50% sterilization 800 times solution and 30% Teflon 5000 times solution. ?

gray mold

Gray mold is the main disease after flowering, which can occur on flowers, petals, fruits and leaves. Brown spots are formed on the fruit during the fruit expansion period, and gradually expand. Gray mold softens and rots fruits, which seriously affects the yield.

Prevention and control: from germination to flowering stage, spraying 25% carbendazim wettable powder 300 times, 50% captan wettable powder 800 times and 50% chlorpheniramine 500-700 times.

Root rot:

Starting from the lower leaf, the leaf edge turns reddish brown, gradually withers upward, and even dies. The middle of the column began to turn dark brown and rotten, and the middle column of the root was red.

Prevention and control: Before strawberry transplanting, use 600 times of 40% asparagus green powder, pour it on the border, then cover the soil and level it for transplanting, which can effectively kill germs in the soil, reduce the germ source base in the field and reduce the chance of infection. ?

verticillium wilt

Verticillium wilt is a kind of soil disease, the main symptoms are deformity of young leaves, yellowing of leaves and extremely rough surface of leaves. Then the leaf edge turns brown and withers inward until it dies.

Prevention and control: strictly introduce disease-free plants; Shorten the update cycle; Use chloropicrin 13.5L-20L or solar film irrigation for soil disinfection; Those who are already sick must be pulled out and burned. ?

insect pest

Aphids, whiteflies and mites are common pests of strawberries, whether in open field or protected field. The better the variety, the more delicious the fruit, the more vulnerable to aphids, and yellow or yellow-green leaves will also attract aphids. ?

Prevention and control: reduce the number of overwintering eggs, thoroughly clear the garden in late autumn, remove weeds and remove sick old leaves in time.

Set up a yellow board, coat it with engine oil to trap aphids and whiteflies, or set up an insect net at the air outlet to block them, or hang a silver-gray plastic film strip to drive away aphids. Effective control of whitefly by releasing aphid wasp. It can be fumigated with fumigants such as chlorpyrifos and dichlorvos.

Spraying: spray 50% aphid or 50% pirimicarb wettable powder 2000 times 1-2 times, 1.8% saijian EC 1000 times, 10% imidacloprid wettable powder1500 times. Whitefly can use 25% chlorpyrifos WP 2500 times solution and 2.5% cypermethrin EC 3000-4000 times solution; Spraying pyrethroid with 5000-8000 times of low residual toxicity and strong contact toxicity twice, with an interval of 5 days, and spraying 20% amitraz emulsifiable concentrate with 2000-3000 times of emamectin benzoate emulsifiable concentrate 100 every 1 500 times. Generally, drugs should be stopped two weeks before fruit picking. ?

Nematodes

Nematodes are not easy to see with the naked eye and need the help of a microscope. The insect is harmful to strawberries for life, and the symptoms are most obvious before and after flowering. Propagation depends on seedlings and soil. Strawberry nematodes are divided into bud nematodes and root nematodes, and strawberry nematodes are also the vectors of virus transmission. ?

Prevention and control: eliminate diseased plants. The transmission of nematodes mainly depends on the infected mother plants and stolons, which are removed together to eliminate pathogens.

Disinfect the soil, dig deep into the soil before planting, fumigate the soil with chloropicrin, and fumigate the greenhouse with soil fumigation and closed shed fumigation at high temperature.

Heat treatment and disinfection: before planting, soak the seedlings in hot water at 35℃ for 10 minute, then cool them before planting. (4) Rotation to avoid continuous cropping and reduce the harm of nematodes. ?

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