Seed Seedling technique of Taxus yunnanensis

Taxus yunnanensis (TaxusyunanensisChengetL.K.Fu) is a rare evergreen tree under national first-class protection, which is suitable for growing in the high mountain area of 2000m to 3500m in northwestern Yunnan. Taxol, an expensive anticancer drug, can be extracted from its branches, leaves, bark and roots, so that in recent years, the market of Taxus mairei has been booming and its price has soared. The annual demand of paclitaxel in the world is more than 4800kg, but the actual annual production is only about 250kg. Although paclitaxel processing plants have been built in Beijing, Shanghai, Liaoning, Yunnan and Sichuan, the supply of raw materials is extremely tight because of the limited wild resources and strict protection by the state.

In 2004, a research group formed by the Management Institute carried out an experimental study on artificial breeding of Taxus yunnanensis, and explored the cultivation of seedlings of Taxus yunnanensis in greenhouse. After 3-year experiments, a set of techniques of Taxus from seed treatment, germination and seedling cultivation were found out, which laid a solid foundation for meeting the afforestation needs of the market in the future. At present, a total of 35000 yew bag seedlings have been cultivated by the management institute, with an average height of 14.6cm and an average ground diameter of 4.72mm, and the seedlings grow normally.

1 kind of real treatment

1.1 damaged seed coat

The seeds of Taxus yunnanensis have long post-ripening period and dormant characteristics, which can only germinate after two winters and one summer, that is, outdoor freezing in winter, high temperature and rain in summer, and autumn sowing the following year; if spring sowing can still be frozen in the outdoor soil after winter, sowing in the greenhouse from late March to early April, and emergence 20 days after sowing. Before sowing, wear out its tough seed coat and hard seed shell (do not grind the seed kernel), make it easy to permeate water and air, and sow and germinate faster.

1.2 variable temperature treatment

The seeds of Taxus yunnanensis have the habit of double dormancy of radicle and Hypocotyl. The radicle needs to go through the stage of high temperature of more than 25 ℃ for one month to break dormancy, and the Hypocotyl needs to break dormancy for about one month under the condition of 20 ℃. In order to accelerate seed germination early, the seeds of Taxus yunnanensis with damaged seed coat were mixed with a small amount of wet sand and frozen in an environment below-3 ℃ for 25 days for 40 days, the Hypocotyl dormancy could be released. After sowing in late winter or early spring, the radicle dormancy could be broken after 2 months or more than 25 ℃, and the seeds would sprout.

1.3 sprouting

The seeds of Taxus chinensis var. mairei treated with damaged seed coat and variable temperature were stored and germinated in wet sand at 1:2. When seeds are needed, take out the seeds and soak the seeds with 0.5% potassium permanganate solution for 1-2 hours, then rinse thoroughly with clean water.

2 soil preparation for bed and soil disinfection

2.1 Land preparation

Choose sandy soil with good permeability as seedbed. The use of comprehensive land preparation, deep 20~25cm above, beating, removal of grass roots, stones, leveling the land.

2.2 make a bed

Make a low bed on the basis of soil preparation, the bed surface is lower than the footpath (ridge) 3~5cm, and the bed width is 1 ~

1.2m, place the topsoil in the center of the seedbed, use the subsoil as a ridge, and then flatten the topsoil.

2.3 soil treatment

Soil disinfection was carried out while making the bed. 6-8g carbendazim per square meter, combined with the bed, was evenly scattered on the bed surface and turned into the soil.

3 sowing

It is broadcast by stripes. The sowing ditch of 15~20cm and deep 3~5cm was widened on the bed surface, and the row spacing was 10~15cm. Mix the germinated seeds with humus or plant ash so that they do not adhere to each other, and then spread the seeds evenly into the sowing ditch. After sowing, it is covered with fiery soil or humus soil with a thickness of 1cm, then covered with a layer of pine needles and watered thoroughly.

4 Seedling management

The seedling season coincides with high temperature and dry weather, so water management is a main work of seedling management. The germinated seeds should not be dehydrated, otherwise, the seeds will lose their germinating power due to the loss of water. In general, water is watered once a day in 2 days, and once a day in case of special high temperature and dry weather.

4.1 Lighting Management

Before the pine needle is pierced after the seedling is unearthed, the pine needle should be removed for 2 or 3 times. The seedlings are afraid of sunburn, so the sun should be shaded in time after removing the pine needles, and the light transmittance of the awning is 15% to 20%, so as to prevent the seedlings from burning. When removing pine needles, you should be careful not to damage the seedlings, and finally pick up the litter and broken grass.

4.2 spraying to prevent disease

In order to prevent the standing blight of the seedlings, before the seedlings were unearthed, the seedlings were poured once with 0.125%-0.167% dimethazone wettable powder. After the mulch is removed, spray with 0.5% Bordeaux solution 0.5% sodium 0.67% or Kangkuling 0.08% sodium 0.1% solution, once every 7 to 10 days, and use alternately.

4.3 weeding

With the increase of temperature, weeds grow rapidly. Therefore, it is necessary to weed in time, try to remove early and small, so as to avoid weeds affecting the growth of seedlings.

5 preparation of nutrient matrix

The nutrition bag of 12cm × 15cm should be selected, and humus soil, loam, plant ash and potassium dihydrogen phosphate should be fully mixed into nutrient matrix at the proportion of 50,30,19% and 1%. After the matrix was prepared, 1% ferrous sulfate was sprayed and mixed evenly, and covered with thin film for 24 hours.

Make a low bed in the greenhouse, the bed surface is below the trail 10cm, and flatten it with a plank. In order to prevent the growth of weeds, the bed can be sprayed with farmer music. Put the matrix into the nutrition bag and place it neatly on the bed, and fill the gap with fine soil.

Cultivation and management of 6-bag seedlings

6.1 transfer the seedling to the bag

When the seedlings of Taxus yunnanensis grow to 7~8cm, the length of the main root is about 10cm, and the lateral root is well developed, so it can be transferred from the seedling bed to the nutrition bag.

Transplanting seedlings should be carried out in cloudy or sunny evening. In order to reduce the damage to the roots of seedlings, the seedlings were dug with soil in one direction with a hoe, and the seedlings were picked out. The roots were placed in 50 × 10-66 ABT rooting powder solution for 0.5 hours and bagged. The nutrition bag should also be watered once 2-3 days in advance, so that the soil is loose and easy to operate when the seedlings are bagged, which is also beneficial to the root extension of the seedlings and improve the survival rate of transplanting. When picking up the bag, sharpen it with a stick, drill a hole in the middle of the bag, release the seedlings, stretch the roots, and compact the soil.

6.2 Water management

After transplanting, the seedlings should be watered thoroughly in time. Special attention should be paid to soil moisture in the next 25 days, watering time should be chosen in the morning or afternoon, and water should be watered once in the morning and once in the evening on a continuous sunny day to ensure the normal growth of seedlings.

6.3 Seedling bed shading

Taxus yunnanensis seedlings like negative environment, the seedlings should be shaded in time after transplantation, and the light transmittance of the awning is 25% to 30%. Within 10-20 days of transplanting, attention should be paid to observing the survival of seedlings, and once dead seedlings are found, replanting should be carried out in time. After 2 or 3 times of seedling replenishment, the number of seedling bags can reach more than 95%.

6.3 Shi Yueba

Topdressing can be combined with watering, mainly by watering the seedlings with light urea water or clear manure water once every 15-20 days. After watering, the seedlings should be washed with clean water in time to avoid fertilizer burns. Topdressing should be carried out several times in a small amount. After the first ten days of October, water and fertilizer should be controlled gradually to promote the further Lignification of seedlings, and fertilization should be stopped after November.

6.4 temperature and humidity control

Taxus yunnanensis seedlings in greenhouse should master and control the temperature in the greenhouse. When the temperature exceeds 35 ℃, the doors and vents should be opened immediately to make the air convection in the greenhouse and reduce the temperature in the greenhouse. The humidity in the greenhouse is controlled at about 85% and 90%.

(7) Disease and pest control

The diseases and insect pests of Taxus yunnanensis seedlings are mainly blight, snails and so on. We should carry out the policy of "prevention first", observe more, spray and control on time, and actively do a good job of prevention. It is observed that Taxus yunnanensis with transplant nutrition bag has no disease and insect damage due to its lower density and stronger resistance.

According to the observation, when Taxus yunnanensis was transferred from June to September, the seedling height increased 1.23cm and the ground diameter increased 0.82mm within 3 months, indicating that the seedlings of Taxus yunnanensis grew slowly, so the afforestation effect was not good in that year, and it was better to cultivate 2-year-old seedlings and leave the nursery in July of the following year.

8 Summary

The main results are as follows: (1) Taxus yunnanensis is a national first-class protected rare tree species, and there is no report of large-scale seed breeding and afforestation, mainly because seed breeding is very difficult and has not been well solved. Through the experimental research for 3 years, the research group has made a great breakthrough in the seed breeding technology of Taxus yunnanensis, and basically solved a whole set of technical links of seed treatment, germination and seedling cultivation. It has taken an important step for the development and utilization of national rare and protected tree species in Yunnan Province, which is of great significance.

(2) the key to seed breeding of Taxus yunnanensis is to master the links of seed treatment. Because the seeds have the habit of double dormancy of radicle and Hypocotyl, the dormancy must be broken in advance through broken seed shell, variable temperature treatment and wet sand germination, so that the effect of seedling uniformity and seedling strength can be obtained.

(3) it is better to raise seedlings of Taxus yunnanensis seeds early. Generally, the seeds can be sowed before the Beginning of Spring, and the seedlings can be transferred to the bag from late May to early June to improve the seedling growth. Through the variable temperature treatment, the emergence time was greatly shortened, and the emergence was very neat. The seedlings must be partially lignified, the main root length is about 10cm, and the lateral roots can be cultivated in bags only when the lateral roots are well developed. Otherwise, the seedlings will grow slowly and some of them will appear the phenomenon of "squatting bags". In the later stage of bag seedling cultivation, we should appropriately control water and fertilizer to promote the further Lignification of seedlings, which is beneficial to improve the survival rate of afforestation.

(4) because the wild resources of Taxus yunnanensis are very limited and belong to the national rare and protected tree species, its rich taxol content makes the market supply fall short of demand, and the price soars all the way. Therefore, to carry out large-scale artificial afforestation of Taxus yunnanensis to meet the market demand and increase farmers' income and get rid of poverty will play a positive role.