Detailed Explanation of the Forcing Cultivation Techniques for Softening-Type Chicory
After the roots are harvested, it is best to subject them to a period of low-temperature treatment before carrying out forcing cultivation. The duration of the low-temperature treatment varies by variety; early-maturing varieties can be treated for a shorter time, while late-maturing varieties should be treated for a longer time, so that tighter chicons can be formed. The methods of forcing cultivation are quite flexible and can be broadly divided into the soil culture method and the water culture method. The soil culture method is a relatively traditional cultivation method and can be carried out by digging trenches in the ground inside plastic tunnels or greenhouses. Its characteristics are low cost and simple operation, but the fact that the chicons formed are not clean is its greatest drawback. The water culture method requires specialized facilities and equipment, which increases costs, but the environmental conditions are easier to control artificially and can create excellent cultivation conditions. The water culture method is further divided into liquid culture and substrate culture. The substrate generally used is peat (peat has good air permeability, strong water retention and few contaminating microorganisms).
The soil culture method is generally carried out on the ground. In the Beijing area, it can be done in plastic tunnels and greenhouses with heating cables laid underneath. First dig a trench 1.5 m wide and 25 cm deep, with the length depending on the site, lay heating cables at the bottom, and cover with 3 cm of soil. After slightly tidying the roots (pulling off rotten leaves and cutting the roots to 14-18 cm in length), they can be placed in the trench one next to another. Once a bed is lined up, sprinkle 6-8 cm of soil on top. Wait until the soil above fills into the gaps between the roots, stop watering, then cover with another 15 cm of soil, leaving more than 20 cm of space above. Covering with black film or any other light-blocking material is fine. When the temperature is maintained at around 18°C, the chicons can be harvested in about 20 days. Note that trenches and soil that have been used cannot be used again.
The water culture method can be carried out indoors or in a greenhouse. In France, growers use wooden troughs with 4 legs specially designed for forcing, carrying out vertical cultivation in the dark with mechanized operation and very high production efficiency. For small-scale cultivation, it can be done in containers 40-50 cm high, or in troughs 30 cm high in a greenhouse or room. When using liquid culture, be careful to wash the roots clean and first pull off rotten leaves and outer leaves. The water level should be below 1/2 and above 1/3 of the roots; circulating water and clean water are best. When using peat as the substrate for cultivation, first spread moistened peat, then arrange the roots. The peat should reach above 2/3 of the roots; fill it up and then water once. In the water culture method, no substrate is placed over the roots, so it is relatively clean.
Whether the soil culture method or the substrate culture method is used, watering only at the beginning is enough to meet the requirements until harvest. Forcing cultivation of chicory can be carried out according to local conditions. As long as the moisture, temperature and darkness conditions required for chicory growth are met, chicory chicons can be produced; each method simply has its own advantages and disadvantages.
After the main chicon of chicory is harvested, secondary shoots can also be produced. If the roots with the shortened stem cut off are allowed to undergo tissue callusing, many fine small shoots can also grow, but much more slowly. The small shoots from the second harvest are also quite distinctive; on the French market they are called barbe de capucin. The yield of chicory chicons converts to a field yield of about 7,500-15,000 kg per hectare, and the output value can reach more than 150,000 yuan.