Detailed Explanation of the Cultivation Techniques for the Chinese Medicinal Herb Yizhi (Alpinia oxyphylla)
Site Selection and Land Preparation
For the seedling nursery, choose a plot with appropriate shade, moisture, good drainage, and loose, fertile soil. After deep plowing and fine harrowing, build seedbeds 1-1.2 m wide and 15-20 cm high. For the field, choose a valley or hillside with shade trees and fertile, moist soil. First cut down low shrubs and weeds, leaving the taller shade trees, then carry out strip land preparation and dig planting holes. Hole spacing 1.5×2 m, hole depth 30 cm, width 40 cm. If intercropping under a rubber plantation, dig holes between the rubber rows at a spacing of 1.5 m, with 2 rows being preferable. Place farmyard manure in the holes as base fertilizer and wait for planting.
Planting Methods
Two methods are used in production: seed propagation and division propagation.
1. Seed Propagation
Harvesting and seed treatment: When the fruits mature each year in May-June, select robust plants with long spikes, large plump fruits, pungent-tasting seeds and high yield as mother plants for seed collection; select large, plump, pest-free mature fruits as seed. After the fruits are picked, peel off the rind immediately and pile them indoors for 2-3 days. Then mix the seed masses with a small amount of fine sand and 30% plant ash, add water, and rub with the hands until the pulp is rubbed clean. Slowly pour out the water together with the pulp, then wash out the seeds. Dry them in a cool place or store them mixed with moist fine sand for later use. Generally, every 10 kg of fresh yizhi fruit can be washed to obtain 1.4 kg of clean seeds. Stored for 2 months, the germination rate can remain at 46-56%, but never store them after sun-drying.
Germination acceleration: The seed coat of yizhi is hard and waxy. Before sowing, soak the seeds in cold water for 1-2 hours, then soak them in warm water at 40°C for 20 minutes. Remove and soak again in cold water for 20-24 hours. After taking them out, accelerate germination in a sand bed or flower pot. Note to water frequently to keep the sand bed moist. After about 10-15 days, the seeds begin to sprout and grow small white root tips; at this point they can be taken out in batches for sowing and raising seedlings.
Raising seedlings: On the prepared seedbed, open shallow furrows 5 cm wide and 2 cm deep at a row spacing of 10-12 cm. Apply barnyard manure or burned soil as base fertilizer. Sow the germinated seeds in holes at a spacing of 5 cm, then cover with soil and cover with weeds, and water to retain moisture. After about 10-15 days the seedlings begin to emerge, and after 20 days they have basically all emerged.
2. Division Propagation
In the main production areas this is usually carried out during the rainy season. Select plants with many tillers, high yield and no pests or diseases, and separate the rhizomes together with the attached new shoots from the mother plant, with 3-5 plants per clump bearing 2-3 new shoots or young suckers. Before planting, cut off the stems and leaves of upright stems above 30 cm, and trim excessively long old and weak roots.
3. Field Planting
The planting period for seed-raised seedlings is divided into spring and autumn; division propagation is best carried out in autumn. For division propagation, plant 3-5 plants per hole; for seed propagation, it depends on the tillering of the seedlings, and those with fewer than 3 shoots are cut into 3 plants and planted in one hole. Do not plant too deep; after planting, cover with soil level with the hole surface and water with root-setting water. Plant 150-200 clumps per mu.
Field Management
1. Seedling stage management: When the seedlings grow 3-4 true leaves, carry out the first fertilization, and thereafter fertilize once every 15 days. Initially apply dilute urine water at 1:10, and gradually increase the concentration each time. After 8-10 months, when the seedlings are 25-35 cm tall with 3-5 new shoots, transplant them into the field.
2. Irrigation and drainage: After planting, the soil must be kept moist at all times. In the dry season, especially during the flowering and fruiting period, if drought occurs, water or irrigate; after heavy rain, drain accumulated water promptly.
3. Weeding and loosening the soil: Within 2 years after planting, weed and loosen the soil 3 times each year, in February, June and September respectively. From the 3rd year the plants enter the flowering and fruiting period, and thereafter management is needed twice a year: the first after fruit harvest in July-August, and the second before flowering in November-December, thoroughly removing weeds and loosening the soil. Loosen the soil shallowly to avoid damaging the rhizomes and tender shoots.
4. Topdressing: Carry out after loosening the soil and weeding. In the 1st year after planting, to promote more tillering, apply more nitrogen fertilizer; in the 2nd year, to promote flowering and fruiting, focus on phosphorus and potassium fertilizer, appropriately combined with organic fertilizer; in the 3rd year, after fruit harvest in July-August, cut off weak plants and plants that have already fruited, hoe away weeds around the clumps, and apply one round of fertilizer to promote tillering and strengthen the plants, applying 100-200 g of compound fertilizer per clump; the second time, from December to January of the following year, apply rotted cow dung, 5-7.5 kg per clump, or barnyard manure 10-20 kg plus 100 g of compound fertilizer, or additionally a small amount of boron, copper, etc., to promote flower bud differentiation and flower formation and development. If conditions permit, apply one round of fertilizer in March-April to strengthen flowers and preserve fruits, or during the flower bud opening period, spray 0.5% boric acid or 3% superphosphate solution in the afternoon or evening to increase the fruit-setting rate and the number of fruits.
5. Cutting shoots: After fruit harvest each year, cut off the plants that have already borne fruit and the diseased and weak plants, to reduce nutrient consumption, promote the growth of new shoots, and increase the number of effective plants that flower and fruit. In addition, also cut off the plants grown from new shoots that sprouted from March to July, because such plants will neither catch up to flower the next year nor survive to the flowering season of the 3rd year before dying, consuming nutrients and affecting yield.