Key Techniques for Raising Southern Yew (Taxus wallichiana var. mairei) Seedlings from Seed
The southern yew (Taxus wallichiana var. mairei) combines medicinal, timber and ornamental value, and has high development and utilization value. Because its seed coat has poor permeability and the dormancy period is long, propagation from seed is difficult. But as long as you grasp the biological characteristics of the southern yew and strictly follow the technical procedures, seedling raising is certain to succeed. The specific operations are as follows:
1. Nursery site selection and fertilization The nursery site should preferably be a paddy field with deep soil, loose structure, rich organic matter, good drainage and no exposure to afternoon sun (it must be paddy field soil from that year's harvest). After harvesting the mid-to-late rice, once the soil is dry, plow deeply once and break up the soil once, then divide into beds. The wide bed is 1.5 m (net bed surface width 1.2 m, path width 0.3 m); the bed height is 20 cm, and the length of the seedbed depends on the nursery site. While preparing the land and making the beds, apply about 8000 jin of decomposed pig and cattle manure per mu and 200 jin of quick-dissolving high-quality compound fertilizer, and mix in 6 to 8 jin of carbofuran to control underground pests. After turning the fertilizer into the soil layer and leveling the bed surface, fill the bed surface with yellow subsoil to a thickness of 5 cm.
2. Sow at the right time After one year of storage, some seeds have split open. At this point sieve them out and wash them clean, soak the seeds in a 0.05% potassium permanganate solution for disinfection for 10 minutes, then rinse them clean with clear water, and sow after drying.
Sowing is divided into broadcast sowing and drill sowing: broadcast sowing means evenly scattering the seeds on the seedbed already filled with yellow subsoil, covering the seeds with yellow subsoil until the seeds are no longer visible, then covering the entire seedbed with moss. For drill sowing, choose a 15 cm wide wooden board and press sowing furrows into the seedbed already filled with yellow subsoil, 2 cm deep, with a distance of 15 to 20 cm between sowing furrows. Sow the seeds evenly in the furrows, cover the seeds with yellow subsoil to a thickness of 1 cm, then cover the sowing furrows with moss.
Note the following: First, strictly control the sowing rate, using 15 kg of seed per mu, otherwise the qualified seedling output rate of two-year-old seedlings will be seriously affected; second, after sowing, broadcast sowing must cover the entire seedbed with moss, while drill sowing only needs to cover the sowing furrows with moss. After the seedlings emerge, do not remove the moss either; keep it on the seedbed for a long time. The advantages of moss protecting seedlings are: it protects the seedbed from rain splash and direct sunlight, prevents the seedlings from being scorched by sunlight and avoids death by suffocation caused by mud sticks forming when stems and leaves are coated with mud, and it keeps the soil loose and moist, reducing the labor of cultivation and weeding. However, the moss covering should be thin, not too thick. If there is a long drought without rain, fine loess can be used to press down the moss, or a sprayer can be used to spray water to keep the seedbed moist.
3. Field management
1. Shading of seedlings Before the seedlings emerge, the shade frame must be set up, with a frame height of 1.7 m. During the dog days, the seedbed must be shaded.
2. Pest and disease control After the seedlings emerge, it is the rainy season. Because there is a lot of rain and high air humidity, the seedlings are easily infected by pathogens and develop root rot and damping-off, causing total failure of seedling raising. Therefore the emphasis is on "prevention", that is, 7 days after the seedlings emerge, spray with 800-times thiophanate-methyl or half-strength Bordeaux mixture (0.5 copper sulfate, 0.5 jin lime, 100 jin water), spraying onto the seedling stems and the undersides and upper surfaces of the leaves.
3. Cultivation, weeding and fertilization During seedling growth, pay attention to weeding and loosening the soil to improve soil aeration. The principle of weeding is: remove small weeds, remove early. For topdressing in the early stage of seedling growth, mainly use nitrogen and phosphorus fertilizers, prepared with 10% dilute human and pig manure plus 0.4 jin urea, applied once every half month. Stop applying in mid-September, and remove the shade net, keeping the frame for use next year.
4. Seedling transplanting If sowing is uneven and causes the seedlings to be too dense or too sparse, transplanting must be carried out from the end of May to mid-June, thinning the dense and filling in the sparse. The transplanting method is: choose a cloudy and rainy day or after rain for transplanting; after covering well with moss, rinse the root ball with clear water and transplant.
4. Management of two-year-old seedlings Before transplanting the seedlings, set up the shade frame and promptly clear weeds from the paths and surrounding areas. For thin and weak seedlings, increase topdressing to promote growth.
Through careful management, one-year-old seedlings reach 12 to 25 cm in height, two-year-old seedlings reach 30 to 35 cm in height with a ground diameter of 0.5 cm, and the seedling yield per mu reaches 60,000 plants.