What are the methods for breeding improved varieties of Schisandra chinensis?
Schisandra chinensis is a plant of the Magnoliaceae family and a valuable medicinal herb, with effects of astringing the lungs, nourishing the kidneys, stopping sweating, stopping diarrhea, and securing the essence. Schisandra chinensis prefers a humid environment (but does not tolerate waterlogging), is cold-resistant, needs moderate shade, and is suited to humus soil or loose, fertile loam. It has strong adaptability and can be grown in both northern and southern China. It often grows wild in coniferous and broad-leaved mixed forests, mountain gullies, along stream banks, among small trees and shrubs, or at forest edges and in open areas within forests.
Methods for breeding improved varieties
1. Seed propagation. After the fruits are harvested in autumn, remove the flesh and wash out the seeds, then dry and store them. Before sowing, the seeds need to be treated as follows: soak the seeds at room temperature for 1 day and night, then mix them evenly with 3 times their volume of clean river sand and bury them in a cooler place. After 3 to 4 months, the seeds crack open and the radicle emerges, and sowing can then begin. When treating the seeds, soaking them in a 100 to 200 ppm gibberellin solution for 24 to 48 hours can promote seed germination. Usually, drill sowing for seedling raising is carried out in late autumn or early spring, with a seeding rate of about 5 kg per mu, covering with 1.5 cm of soil, watering thoroughly and covering with grass to keep the soil moist. After the seedlings emerge, remove the covering grass, set up a frame for shading, and keep a small amount of sunlight. Transplanting can be done in early spring of the second or third year.
2. Layering propagation. Before the plants begin to grow in early spring, bury part of the branches in the soil and water frequently to keep the soil moist. After the branches produce new roots, cut the branches from the plant in late autumn or the following spring to separate them, and then transplant.
3. Cutting propagation. Before growth begins in early spring or during the rainy season after flowering, cut firm and robust branches into 12 to 15 cm long sections (the cut ends must be smooth) and insert them diagonally into the seedbed, with a row spacing of 12 cm and a plant spacing of 6 to 10 cm, then set up a shed for shading and water frequently to promote rooting and survival, and transplant in the spring of the following year.
Field management techniques
1. Transplanting. There are two methods for transplanting Schisandra chinensis: one is to use natural supports. That is, use trees as supports, and tree species chosen as natural supports should preferably have smaller leaves and not overly vigorous growth; the second is to use artificial supports. For artificial supports, Schisandra chinensis seedlings can be planted at a spacing of 1 m between large rows, 60 cm between small rows, and 50 cm between plants, with the rows oriented north-south to facilitate ventilation and light penetration.
2. Comprehensive field management. Schisandra chinensis seedlings grow slowly, so attention should be paid to weeding, loosening the soil, and appropriate watering. After the second year, the supports can be used for branches to climb on, and attention should be paid to maintaining ventilation and light penetration to promote growth. In addition to applying sufficient base fertilizer at transplanting, topdressing must be carried out every spring, with 1500 to 2500 kg of barnyard manure or compost and 15 to 20 kg of superphosphate per mu. To regulate plant nutrition and reduce unnecessary nutrient consumption, pruning is also needed, as follows: the pruning season is each year after the plants enter dormancy in winter and before growth begins in spring. The pruning method is, apart from selecting and retaining 3 to 4 thick branches per plant for cultivation, to cut off all the rest, and cut off short branches as well as overly dense medium fruit branches and long fruit branches, so as to increase ventilation and light penetration and raise the fruit yield.
3. Pest and disease control. Leaf blight and leaf-rolling insect pests are common pests and diseases of Schisandra chinensis. Leaf blight starts from the leaf tips and leaf margins, gradually spreads to the entire leaf surface, causing the leaves to yellow and drop, and in severe cases the fruit clusters drop, or even the entire crop is lost. Before onset or in the early stage of the disease, a 1:1:100 Bordeaux mixture can be sprayed, once every 7 to 10 days, for several consecutive sprays; leaf-rolling insects damage the plants as larvae, causing leaf rolling. For control, a 1500-fold dilution of 50% phoxim emulsifiable concentrate or a 1500-fold dilution of 50% phosphamidon emulsifiable concentrate can be sprayed. This can achieve good control results.