Key technical points of seedling raising and transplanting in licorice cultivation
In licorice cultivation there are three propagation methods: direct sowing, seedling raising and transplanting, and rhizome propagation. By comparison, direct sowing gives lower yield and a larger proportion of rhizomes; seedling raising and transplanting gives high yield but poorer quality; rhizome propagation gives high yield and a large proportion of roots, which are much sought after on the market, so rhizome propagation is mostly used in production. This cultivation method is described below.
Site selection and land preparation
Choose sandy loam soil with deep, loose, fertile layers. After the site is chosen, apply 3000 kg of farmyard manure, 50 kg of superphosphate and 20 kg of potassium sulfate per mu as base fertilizer. The ploughing depth must reach more than 40 cm. Level and rake the soil fine, and make flat beds 110 cm wide.
Selecting seed stems
When harvesting licorice in February, select straight, thick and strong rhizomes with short internodes and adventitious roots at the nodes to use as seed stems. Cut the selected seed stems into small sections 15 cm long, so that each section has at least three nodes with buds. Soak the cut seed stems in a 30 ppm gibberellin solution for 3 to 5 minutes, then plant them immediately.
Planting
On the prepared bed surface, open three small furrows 15 to 18 cm wide and 5 to 7 cm deep along the direction of the bed ridge. Place two rows of seed stems in each furrow, end to end, spray with an 800-fold dilution of phorate, then cover with soil so that the seed stems are 4 to 5 cm below the bed surface. Firm the soil with your feet, water thoroughly once, and when the bed surface no longer sticks to the feet, hoe lightly to preserve soil moisture and raise the ground temperature.
Field management
Licorice propagated from rhizomes emerges slowly; at a ground temperature of 18°C it takes about 20 days to reach 80% emergence. Therefore, during this period, drought resistance and moisture conservation work must be done well to keep the bed surface moist, which favors emergence. Seed stems sprouted with gibberellin are slender after emergence; spray daminozide or chlormequat according to the instructions to make them thick and strong. After the seedlings emerge evenly, broadcast 15 kg of urea per mu and spray 30 to 60 kg of a 0.3% potassium dihydrogen phosphate solution. After that, hoe frequently to control weeds, actively control underground pests, and ensure full and vigorous seedlings.
Pest and disease control
In licorice production, the most common insect pests are cutworms and wireworms, and the most common disease is powdery mildew; these two are the main causes of reduced yield. The control methods have been described above and are emphasized here so as to draw attention. Other pests and diseases can be controlled according to their symptoms.
Harvesting and processing
Harvesting can be done from the Autumn Equinox of the second year after planting to before sprouting in the third spring. Dig starting from one end of the bed, dig out the roots intact, dig out the rhizomes cleanly, cut off the stems and leaves, shake off the soil and sun-dry. After drying, tie into bundles and they can be sold. The roots and rhizomes can also be tied into separate bundles and sold separately. Licorice commodities are best when dry, free of impurities and rich in powder.