How to Propagate Yew? A Detailed Guide to Common Propagation Methods
I. Sexual Propagation
In earlier years, the seedling emergence rate of wild yew sown from seed was less than 10%. Scientific research found that its seeds have a dormancy period lasting several years. After using outdoor variable-temperature storage and applying chemicals to break seed dormancy, the emergence rate can be raised to over 70%-80%, enabling common yew to overcome the difficulties of sexual propagation and making artificial mass seedling cultivation and large-scale planting possible.
1. Seed collectionCollect ripe fruit from September to October, place it in a basin, add an appropriate amount of coarse sand and water, and rub it repeatedly on a wooden board to rub off the outer skin and flesh of the seeds, then rinse repeatedly with clean water and set aside for use.
2. Seed soakingBefore sowing, first soak the seeds in a 1:1 mixture of 50-proof baijiu and 40°C warm water for 20 minutes, then remove them and soak them in 500 PPM gibberellin for 24 hours. This can induce the production of hydrolytic enzymes and promote germination.
3. SowingExperiments show that the fresher the seeds, the higher the emergence rate. Seeds sown within one week after collection can reach a germination rate of over 90%, while seeds sown at the Beginning of Spring have a germination rate of only 50%. Therefore, after collecting seeds in September and October, raise seedlings immediately. For the seedbed, make it 1.2 m high, with the length calculated according to the amount of seed, using 100 sq m of seedbed per kilogram of seed. While turning the soil in the seedbed, apply farmyard manure; apply 100 kg of phosphate fertilizer and 30 kg of nitrogen fertilizer per mu. Use 2 kg of powdered insecticide to kill underground pests, then open drainage channels and set aside for use. Dry the surface water of the soaked seeds, add an appropriate amount of fine sand to facilitate broadcasting, evenly broadcast at a rate of 5 kg per mu onto the seedbed, water thoroughly with clean water, and shortly afterward cover with prepared fine soil to a thickness of about 1 cm.
4. Seedling careAfter sowing, immediately cover the seedbed flat with plastic film. After the Beginning of Spring, change the flat film to an arched film and begin raising the temperature to hasten germination. Check temperature and humidity at any time; if the temperature is too high, uncover one side of the agricultural film to cool it down. After germination begins, water the seedlings about once every 4 days. When the seedlings have two leaves and one heart, remove the film to harden the seedlings and thin them for wider spacing. When the seedlings grow to 5 cm tall, thin the dense areas to maintain a basic population of 20,000 plants per mu, and heel in the thinned seedlings in other plots at a spacing of 15 x 20 cm. Weeding and topdressing during the seedling stage: weeds often grow in the nursery, and they can be removed by hand or controlled together with loosening the soil. After each loosening of the soil, apply 10 kg of urea per mu, 5 kg of potassium chloride, and decomposed farmyard manure. During the seedling stage, topdressing is needed three times to ensure strong seedlings. During the seedling stage, spider mites, aphids, cabbage caterpillars, and others may appear, and they can be controlled by spraying dichlorvos, dimethoate, and similar insecticides. After the seedling grows in the seedbed for one year, when the seedling height is above 30 cm and the stem diameter is 0.3 cm, it can be lifted from the nursery for afforestation.
II. Asexual PropagationThis mainly refers to cutting propagation. Taxus media is a hybrid variety, and to maintain the purity of the variety, it is generally limited to asexual propagation.
1. TimingIn spring, it can be done from February to April; in autumn, it can be done from September to November. During this period, the temperature is generally above 15°C and below 25°C, so as to ensure that the cuttings lose less moisture through evaporation and the bases heal well.
2. CuttingsFor cutting propagation, the shoots must first be free of pests and diseases and be vigorous branches, with a thickness of 0.3 to 0.8 cm and a length of 10 to 15 cm. After cutting the branches, first remove the lower 1/3 of the leaves, place them in rooting solution to soak for two hours, then insert them into the seedbed in time.
3. SeedbedIf conditions permit, the seedbed can be made inside a greenhouse, and the substrate can use perlite or vermiculite. For small-scale propagation, sandy soil can be used, with 1/3 humus soil added. The seedbed can be made 1.2 m wide, with the length depending on the seedling propagation needs. The substrate layer should be about 20 cm thick. First irrigate to settle the substrate, then carry out cutting.
4. CuttingInsert the prepared cuttings into the seedbed at a plant spacing of 4 cm and a row spacing of 10 cm, with 1/3 of each cutting inserted into the soil.
5. ManagementSpring cuttings generally take 30 days to root, while autumn cuttings generally root only the following year, so seedbed management is the key to cutting survival. After insertion, irrigate in time. On the seedbed, use bamboo strips to build a frame 15 cm above the ground, and spread plastic film flat over the frame. For spring cuttings, remove the film after April and cover with a shade net. For autumn cuttings, the film must remain covered until April of the following year; when the temperature is high, also replace it with a shade net. The main purpose of the film is to maintain humidity in the seedbed, and in winter it can also increase the seedbed temperature. A shade net with a shading rate of 80% generally gives better results. For large-scale propagation, the shade net should be set up about 2 m above the ground; for small amounts, it is enough to cover the seedbed. After insertion, if the leaves remain green, neither withered nor yellow, it indicates that management is normal. At 20 days, pull out a cutting to check whether the cut at the base shows signs of healing and cell tissue growth; this is an important sign before rooting. Spring cuttings root soon after the cell tissue increases. For autumn cuttings, after this cell tissue increases and the temperature drops, they wait until after February of the following year when the temperature rises, and only then continue growing from the original cell tissue to form new roots. However, this nodular tissue also has the function of absorbing water and nutrients and can maintain the cutting's own water requirements. After new roots grow, fertilizer can be applied as topdressing, using 20 jin of urea and 5 kg of compound fertilizer per mu of seedbed, applied by irrigation. Before lifting from the nursery, topdressing can be applied 2 times, and the amount of fertilizer can depend on the seedling condition. Foliar fertilizer can be applied after 10 days, generally once every 20 days. In the early stage, it can promote base healing; after rooting, it can promote root growth and the growth of upper small branches. During the small seedling stage, weeds in the seedbed should be removed frequently to avoid competing with the seedlings for water and nutrients. For spring cuttings, after September of that year, the root system is basically well developed, reaching about 20 roots, with root length about 15 cm, and 3 to 5 new branches growing on the upper part, with a length of more than 10 cm. For autumn cuttings, roots begin to grow after February of the following year. After June, they can be heeled in or transplanted (too high temperatures in June and July make transplanting unsuitable), or they can continue to be managed in the seedbed. After September, they can be transplanted. Autumn cuttings have a longer growth period and grow better than cuttings from the same year. Regardless of which cutting method is used, as long as management is done well, the survival rate can reach over 90%, making it the main propagation method currently used to develop Taxus media.
III. Micro-cutting Propagation MethodAlso called the "non-test-tube tissue culture method." Its characteristic is that it can increase the propagation multiple of limited material, and it is used when the number of mother trees is small. It also has low propagation cost and large propagation output. The disadvantage is that the seedling formation period is extended by 1 year before transplanting, and after rooting, the plants need to be heeled in for 1 year before they meet the requirements for lifting from the nursery. The propagation technology is relatively demanding and can only be used with a certain technical foundation and production conditions. Cover with a shade net on top, keep the seedbed moist at all times, and strictly prohibit direct sunlight. As long as the leaves do not turn yellow or wither and remain green, it indicates normal growth. After about 20 days, check whether the cut at the base of the cutting has healed and whether cell tissue has grown; this is the main state before rooting. During this period, foliar nutrient fertilizer can be applied as topdressing. After 40 days, check and new roots will have grown, and nitrogen fertilizer can be applied by watering. At the seedling stage, apply at most twice. Generally, spring cuttings are transplanted in autumn, and autumn cuttings are transplanted before June of the second year or in September. The standard for transplantable seedlings is that they should have more than 20 fibrous roots, a root length of 10 cm, and generally about 3 new branches growing on the upper part, with a length of 5-10 cm.