Detailed Explanation of Key Points on Seed Sowing and Seedling Raising Techniques for Schisandra chinensis
1 Seed collection
After late July, seed selection can begin in artificially cultivated gardens. The selection standard is to designate fruit-bearing trees with clusters longer than 8 cm, average berry weight above 0.5 g, and early berry coloring as seed collection trees. Harvest the fruit in mid-to-late September, pile and ferment for a few days, then select by water, skimming off shriveled seeds, rubbing away the fruit skin and pulp, washing clean, and placing in a cool place to dry in the shade for later use.
Depending on the season, sowing and seedling raising of Schisandra chinensis is divided into two methods: autumn sowing and spring sowing. Autumn sowing means sowing the seeds collected that same year directly into the nursery field, while seeds used for sowing the following spring must undergo stratification and pregermination treatment.
2 Stratification and pregermination treatment
From mid-to-late December to early-to-mid January, first soak the seeds in clean water for 2-3 d, changing the water once a day. Then mix the wet seeds with fresh, clean, fine river sand at a ratio of 1:3 and place them outdoors under natural conditions for warm stratification treatment. The sand moisture should be such that it forms a ball when squeezed tightly in the hand without dripping, and does not scatter when the hand is released, usually 40%-50% of saturated water content. The stratification treatment of Schisandra chinensis seeds requires 80-90 d. About half a month before sowing, sieve the seeds out of the stratified wet sand, soak them in cool water for 3-4 d, changing the water once a day. When the seed coat of the soaked seeds cracks or the radicle emerges, and the cracking rate reaches about 30%, sowing can begin.
If before stratification the seeds are soaked for 24 h in a 250 ml/l (ppm) gibberellin solution or a 1% copper sulfate aqueous solution, the stratification time can be shortened by about 1/3.
3 Selection of nursery land
In order to cultivate excellent Schisandra chinensis seedlings, the nursery land should preferably be a flat, loose, and fertile sandy loam plot with convenient water sources and good drainage; old ginseng land may also be used. Seedling raising is best done in beds, and beds can be made according to different soil conditions. For low-lying, waterlogged nursery land with abundant rain, plowing and harrowing should be carried out before the soil freezes in the previous year, with a plowing depth of 25-30 cm. Apply base fertilizer in combination with autumn plowing, applying 10-15 kg of decomposed farmyard manure per sq m, mixing it thoroughly and evenly with the bed soil, and raking the bed surface level before sowing. Regardless of the type of seedbed, there must be a loose soil layer of no less than 15 cm in the bed soil.
4 Sowing and post-sowing management
(1) Direct sowing in the open field. Spring sowing (early May) and autumn sowing (before the soil freezes) may be carried out. Before sowing, make low beds 1.2 m wide and 10 m long. Drill sowing is used, that is, opening shallow furrows 2-3 cm deep on the bed surface at a row spacing of 15-18 cm, and pressing the bottom of the furrows. Sow 100-120 g of seeds per bed, with 5 kg of seeds used per mu. After sowing, cover with 2 cm of fine soil, press with a wooden roller, water thoroughly, and then cover the bed surface with a layer of straw curtain to maintain soil moisture. Seedlings emerge 20-30 d after sowing. When the emergence rate reaches 50%-70%, remove the straw curtains in batches and set up a simple shade shed, keeping the light transmittance below 30%-40%. Remove the shade when the seedlings grow to 5-6 cm tall. Thin the seedlings when 3-4 true leaves have grown, with a plant spacing of 3-5 cm. Because the apical buds of Schisandra chinensis seedlings are particularly sensitive to certain herbicides, weeding should mainly be done manually. The height growth of current-year seedlings is generally 10-15 cm; those less than 10 cm tall should be covered with soil to overwinter and then cultivated for another 1 a for garden establishment.
(2) Seedling raising in protected facilities. In early April, cover with plastic greenhouses and make paper-bag nutritional containers with specifications of 6×6×10 cm or 7×7×10 cm. The nutritional soil ratio is fine river sand to humus soil at 1:3, with 5% decomposed farmyard manure (pig manure) and 0.3% diammonium phosphate (ground into powder) added. Before sowing, water the nutritional soil in the bottom layer of the containers thoroughly, sow 2 seeds in each paper container, and cover with soil 1.0-1.5 cm thick. When sowing, an appropriate amount of carbendazim should be mixed into both the bottom soil and the covering soil. After sowing, spray with 800-1000 times diluted amobam along with watering. After sowing, maintain appropriate humidity, generally watering once every 2-3 d. After the seedlings emerge completely, shade for about 20 d. When the temperature is above 30 degrees C, pay attention to ventilation and cooling.
(3) Seedling transplanting and nursery field management. In mid-to-late June, transplant the seedlings with soil balls into the nursery. Before transplanting, the nursery land should be fully prepared with plowing, harrowing, and ridge formation. When transplanting, use a flat hoe to break the ridge and open a furrow 15 cm deep, and apply base fertilizer (400-500 kg of high-quality farmyard manure per mu). Place the paper-container seedlings in the furrow at a plant spacing of 10-15 cm, fill level with fine soil, water thoroughly, and finally close the ridge. Topdress the seedlings twice during the seedling stage. The first is carried out when the shade shed is removed, opening furrows between seedling rows and applying 200-250 g of ammonium nitrate and 50-60 g of potassium sulfate per seedbed; the second is carried out when the seedlings are about 10 cm tall, applying 300-400 g of diammonium phosphate and 60-80 g of potassium sulfate per seedbed. After fertilizing, appropriately increase the frequency of watering to promote seedling growth.