Key Technical Points for Cultivating Chinese Toon in a Solar Greenhouse
Chinese toon, also known as chun ya (toon sprouts), is rich in nutrients. Every kilogram of tender stems, leaves and sprouts contains 840 g of water and 98 g of protein, and also contains vitamin C, A and B as well as calcium, phosphorus and other substances. Chinese toon can be stir-fried, served cold with dressing, deep-fried, eaten fresh, eaten dried or pickled.
Greenhouse cultivation of Chinese toon mainly relies on the nutrients accumulated in the tree body during the open-field growing period for sprout growth; after rooting, it can recover a certain absorption capacity, and a moderate supply of fertilizer and water supports the growth of Chinese toon.
1. Raising seedlings. Inside the greenhouse, high-density planting is required, the number of seedlings used is large, and the space is small, so it is advisable to produce dwarfed, multi-branched, strong seedlings. Sow seeds in the open field under protected conditions, and after sowing set up small arched sheds for cold protection and carry out careful management; or sow in February, early to mid-month, in a sunny seedbed inside a greenhouse or plastic tunnel. After the seedbed is prepared by tilling and fertilizing, water it, sow pre-germinated seeds at spaced points, cover the seedbed surface with plastic film after sowing, and keep the seedbed at about 25°C during the day, removing the film at emergence. After the seedlings emerge evenly, lower the temperature appropriately, keeping it at 20-23°C during the day and 13-15°C at night. Thin the seedlings 1-2 times, prick out the seedlings into the seedbed at 3-4 hours, and transplant them to the nursery when they have 7-8 leaves. Plant seedlings in level beds with a row spacing of 30-40 cm and a plant spacing of 25-30 cm. Do not pinch out the growing tips of the seedlings; mostly cultivate them into single-stem seedlings suitable for greenhouse planting.
2. Planting and management. From mid-October to early November, after the seedlings shed their leaves and the terminal buds enter dormancy, lift the seedlings promptly to prevent freezing damage. When digging up the seedlings, keep about 20 cm of roots. Heel the seedlings in a trench, cover the roots with soil, water them, and cover the plants with straw bags and the like for frost protection, ensuring a low temperature below 10°C so that the nutrients in the leaves fully flow back into the stems and buds, completing the dormancy period after about 15 days. Plant them in the greenhouse within November when the average daily temperature is 3-5°C. Inside, dig wide trenches 0.5 m deep in a north-south direction, plant the seedlings at 70-80 degrees, with a plant spacing of 4-5 cm; plant 100-150 current-year single-stem seedlings per square meter, and 80-120 two-year-old branched seedlings, then water after planting. After 3-5 days, seal the film before the cold wave arrives.
After the film is sealed, the greenhouse temperature gradually rises. In the early stage, keep it at 15-22°C during the day and about 10°C at night; after 40-50 days, sprouts can emerge. After sprouting, keep the temperature at 18-24°C during the day and 13-15°C at night. The coloring temperature for toon sprouts is above 22°C; when the temperature exceeds 28°C, ventilate for 2-3 hours at noon on sunny days. In mid-to-late December, if the toon sprouts have not yet broken dormancy, or when the minimum temperature inside drops to 4-5°C, a stove can be temporarily lit to raise the temperature. Water the seedlings 10-15 days after planting and 3-5 days before each harvest; when the air is dry, spray water into the air, keeping the relative air humidity at 60-70%. After harvesting the first crop of Chinese toon, apply topdressing, and thereafter apply a light fertilizer solution or foliar fertilizer after each harvest. When nutrients are insufficient, the toon sprouts become thin and elongated, turn yellow, and the weight of individual sprouts decreases.
3. Harvesting. Harvest when the toon sprouts are about 20 cm long and their color turns reddish-brown. Harvest the first crop of Chinese toon before the Spring Festival, and thereafter harvest once every 15-20 days, for a total of 3-4 harvests, ending before open-field Chinese toon comes on the market. Greenhouse Chinese toon is relatively tender, so the sprout tips must be cut with scissors or sliced off with a sharp knife; they must not be snapped off by hand, to prevent damaging the sprouts and the tree body.
After harvesting ends, gradually remove the film to harden the seedlings. After hardening, dig out the seedlings and transplant them to the open field, carry out fertilization and watering according to the management methods of the previous year, and move them into the greenhouse again for use in winter.