Houpo is a traditional Chinese medicine. Due to the slow growth of the Houpo tree and the fact that the medicinal part is often the bark, there is a scarcity of Houpo resources. The government has already included Houpo in a resource protection project for cultivation, so artificial propagation of Houpo is becoming increasingly popular. There are generally two methods of propagation for Houpo: sexual reproduction and asexual reproduction. Below, we will introduce the methods of sexual reproduction.
(1) Seed Collection
① At an altitude of 500-2000 meters, select healthy trees that are 16-25 years old, with thick bark, glossy appearance, and strong growth. In late September to early October when the seeds are mature, select fruits that are large, plump, free from disease and pests, and fully ripe. Collect the fruits together with the seeds.
② Select trees for seed collection: Choose trees at an altitude of 1000-1600 meters, over 16 years old, free from disease and pests, and with vigorous growth. Label them and give special care and meticulous maintenance. Apply sufficient organic fertilizer or calcium superphosphate before flowering to provide adequate nutrients. When the flowers are about to bloom, depending on the size, age, and vigor of the tree, leave 6-9 flowers on each tree as fruit seeds. The remaining flower buds can be removed, dried, and used as medicinal material, known as "Houpo flower." The seeds collected from these designated trees are large, with plump and uniform seeds, and the germination rate can reach over 95%.
③ Seed collection time: From late September to mid-October, when the fruit skin turns purplish-red and slightly cracks open, and the reddish seeds start to appear, carefully collect the fruits. After collecting the fruits, do not rush to remove the seeds. Once the seeds are taken out and separated from the fruits, they lose their protective layer and are prone to dehydration and drying, which can affect the germination rate.
(2) Seed Maintenance
① Traditional simple preservation and maintenance method: Collect the seeds together with the fruits, without removing the seeds. Hang or place them in a cool and ventilated place to dry together with the fruit skin and pulp. Wrap them in palm leaf sheaths and store them in a cool and dark place. The next spring, they can be sown, and the germination rate is generally over 60%.
② Sand storage method: Mix the harvested seeds with sand in a ratio of 1:3, and bury them in moist soil. If there are fewer seeds, they can be stored together with the sand in a wooden box, but the appropriate humidity should be maintained. With the sand storage method, the germination rate of the seeds can reach over 80%, and it is also convenient for transportation.
In addition, there are other methods such as pit (cellar) storage and fresh fruit storage.
(3) Seed Treatment Before Sowing
The seeds of Houpo have a waxy protective layer on the outer shell, which makes it difficult for water to penetrate and the seeds difficult to germinate. To promote rapid germination, the seeds need to be properly treated before planting to remove the waxy layer, otherwise it will affect the germination rate. Here are several commonly used methods for treating spring-sown seeds:
① Simple treatment: When the fruits are ripe from September to November, harvest the seeds and put them in a fine or hole-free bamboo sieve or small winnowing basket. Soak them in shallow clean water and rub them with hands until the reddish waxy layer is completely removed. You can also add some coarse sand during the rubbing process to facilitate the removal of the waxy layer. After removing the waxy layer, spread them out to dry before sowing. This method is suitable for autumn and winter sowing. For spring sowing, the waxy layer is temporarily not removed for storage convenience.
② Soaking treatment: a. Take out the dried stored seeds and soak them in clean cold water for 8-10 days. Take them out and sun-dry them for 10-20 minutes until the seed coat naturally cracks open before sowing. b. After soaking the seeds for 48-96 hours, put them in coarse sand and rub off the waxy protective layer on the surface of the seeds before sowing. c. Take out the seeds and put them in a fine bamboo sieve, soak them in water for 30-48 hours, trample them with feet, and then rub off the waxy layer with hands before sowing.
③ Soaking with laundry detergent: Dissolve an appropriate amount of laundry detergent in warm water, put the Houpo seeds in the detergent water, soak them for 12-24 hours, wash off the waxy layer, and then air dry before sowing. This method also has the effect of disinfection and pest control.
It is important to note that only treat the seeds that will be sown, and the seeds with the waxy layer removed should be sown immediately. Additionally, when it comes to storage, maintenance, and transportation of the seeds, it is not recommended to use non-breathable materials such as plastic bags to avoid seed molding.
(4) Sowing Methods
① Spring Sowing
Generally, sowing is carried out from the Spring Equinox (mid-March) to Qingming Festival (mid-April), which is called "spring sowing." After treating the seeds according to the appropriate method, sow them in prepared seedbeds. The sowing methods include broadcast sowing, row sowing, and hole sowing.
a. Broadcast sowing: Broadcast sowing is not easy to sow evenly, manage, weed, or transplant. The survival rate is also low, so it is generally not recommended.
b. Row sowing: Row sowing is commonly used as it is convenient for management and seedling removal. In a prepared seedbed, open shallow furrows with a depth of 4-8 cm and a width of 8-12 cm, with row spacing of 20-30 cm. Evenly sow the treated seeds in the furrows of the seedbed, about 5-10 cm apart for 1-2 seeds per furrow. After sowing a row, cover the furrows with fine soil mixed with grass ash or decomposed leaf soil, about 3-4 cm thick, and lightly compact. Continue sowing in this orderly manner. After all the sowing is completed, cover the seedbed with a layer of pine needles, straw, or wheat straw of 1.5-3 cm thick, and water it to keep it moist. This is known as "watering for seed establishment."
c. Hole sowing: In a prepared seedbed, dig holes in rows, starting from one end of the bed. The row spacing is 30 cm, and the plant spacing is 10-15 cm. The hole depth is 5-10 cm. Put 1-3 seeds in each hole and cover them with fine soil mixed with grass ash or other decomposed leaf soil. Start from one end and sow while moving backward. After sowing, cover with rice straw, pine needles, or wheat straw. After covering, water it to keep it moist for seed establishment.
d. Plastic film-covered seedbed method: Using plastic film for seedbeds can promote early and good seed germination and improve germination rate. This method can adopt either row or hole sowing. In early March, on a well-prepared seedbed, sow the seeds with a plant spacing of 17 cm x 17 cm, a hole depth of 4-6 cm, and 1-2 seeds per hole. Cover them with fine soil mixed with grass ash, about 3-5 cm thick. After sowing, cover the seedbed with plastic film to keep the soil moist and warm, preventing the attack of late frost. About 3-5 days later, when the soil temperature rises, if it reaches above 25°C, the plastic film at both ends of the seedbed should be opened for ventilation and cooling to remove acidity. Usually, the soil temperature should be maintained at 18-23°C for seed germination. The plastic film is arched, 60 cm high. After 30-38 days of sowing, when the seedlings emerge from the ground, with a germination rate of 60%-75%, and grow to 3-6 cm, "weeding" should be carried out. Weeding is done by removing the plastic film during the day when the temperature is high and covering it again at sunset. Repeat this process for 5-7 days until all the seedlings emerge and grow to 4-6 cm, then the plastic film can be removed, allowing the seedlings to grow naturally.
② Autumn Sowing (also known as Winter Sowing)
Many years of planting observation have shown that sowing fresh Houpo seeds in late autumn and early winter can promote easy germination, high seedling emergence rate, save seeds, and reduce storage and maintenance processes, as well as labor. If conditions permit, autumn sowing with fresh seeds is recommended.
The site selection and soil preparation for autumn sowing are the same as for spring sowing. The seedbed site should be non-cultivated land (i.e., land that has never been planted before), but it should be fertile humus soil, sandy loam, or sandy soil. For cultivated land, attention should be paid to disinfection, sterilization, and pest control.
The ideal time for autumn sowing is generally from mid-October to early December, with the period from November 15th to 25th being the best.
The sowing method usually adopted is row sowing. On a prepared seedbed, open a shallow groove 5 cm deep, with row spacing of 25 cm and plant spacing of about 5 cm. Sow one seed per plant and cover with 2-3.5 cm thick decomposed organic fertilizer soil. Then cover with 2 cm thick rice straw, pine needles, or dry crushed corn stalks to maintain the temperature and humidity of the seedbed and prevent frost damage.
Fresh seeds are preferable for autumn sowing. Select ripe and fully matured red fruits with plump and uniform seeds, and directly sow the peeled seeds. The emergence rate can reach around 95%.
Houpo seeds have hard shells and small pores, and the outer shell has a layer of waxy protective coating, making it difficult to absorb water and germinate after sowing, resulting in a low germination rate. Therefore, fresh seeds also need to be appropriately treated before direct sowing to facilitate germination.
a. Fresh seed treatment: From mid-September to mid-October (between Bailu and Hanlu), select fruits that are large, fully ripe, uniform in size, and mature. Put them in a bamboo sieve, soak them in shallow water, and remove all the red waxy layer. Remove any unripe seeds floating on the water and take out the seeds that sink to the bottom. Spread them out to dry before sowing.
b. Sowing fresh seeds: On a prepared seedbed, dig a shallow groove about 5 cm deep. With a row spacing of 30 cm, evenly sow the seeds without the waxy layer, with a plant spacing of 5-8 cm. After sowing, cover with fine mud and decomposed organic fertilizer soil. Then cover with rice straw, pine needles, or tree leaves to keep the soil moist. The seedlings can emerge the following year from late April to early May.
c. Preservation of fresh fruits: If the harvested fresh Houpo fruits are not immediately used for sowing or need to be transported to other areas for cultivation, it is necessary to preserve the seeds temporarily.
