Tutorial on High-Yield Cultivation Techniques for Isatis Root, Latest Planting Methods Explained

Isatis root, commonly known by other names: indigo root, blue indigo root, Daqing root, is a traditional Chinese medicinal herb. It is produced throughout China. Isatis root is divided into North Isatis root and South Isatis root. North Isatis root comes from the roots of Isatis indigotica and Isatis indigotica var. in the Brassicaceae family; South Isatis root is the rhizome and roots of Baphicacanthus cusia in the Acanthaceae family. It has the effects of clearing heat and detoxifying, cooling blood and reducing swelling, and soothing the throat.

Isatis root is not suitable for planting in low-temperature waterlogged land, as the roots rot easily after waterlogging. To reduce the occurrence of pests and diseases, it is advisable to ridge-cultivate it with grasses and legumes; if the soil is fertile, it can also be planted as a catch crop.

Land preparation and fertilization

Isatis root is a deep-rooted plant. Apply 4-5 cubic meters of decomposed organic fertilizer per 667 sq m. Before application, crush it finely first, then spread it evenly on the ground. Deep plow 20-30 cm, rake fine and level, and make flat beds 1 m wide. When the ground is dry, water thoroughly, and sow when the surface soil is slightly dry and loose.

Sowing

It is divided into spring sowing and summer sowing. Spring sowing is around Qingming, at the latest no later than Guyu. Summer sowing is around Mangzhong. When sowing, in the prepared bed, draw furrows 1.5 cm deep at a row spacing of 20 cm, sow the seeds evenly into the furrows, then cover with soil, level, press lightly, and water immediately. Generally, seedlings emerge in 7-10 days, using 1.5-2 kg of seed per 667 sq m. In some production areas, Isatis is intercropped with grain crops or vegetables, which can make full use of the land and achieve increased income.

Field management

After sowing, keep the soil moist. When the seedlings are 6-10 cm tall, thin to the final stand (you can also thin to the final stand in one go, or first thin and then final-thin), removing the weak and keeping the strong. If there are gaps, transplant in time to fill them. The focus of management is intertillage and weeding. After the seedlings emerge, hoe shallowly to prevent crushing the seedlings. After final thinning, loosen the soil and weed, keep the surface loose at all times, and keep the field free of weeds. For those mainly harvesting Daqing leaves, apply topdressing 3 times a year. The first topdressing is after final thinning, applying 10-12 kg of urea per 667 sq m, applied in furrows between rows, and watered in case of drought; the second and third times are applied immediately after harvesting the leaves. For those mainly harvesting Isatis root, do not cut the leaves during the vigorous growth period, and apply less nitrogen fertilizer; 30-40 kg of cake fertilizer can be applied.

Management of seed-production fields

Spring-sown Isatis cannot flower and set seed in the same year. In order to harvest seeds, it must undergo low temperatures. There are the following two methods: First, when digging and harvesting Isatis root in late October, select pest-free, robust, straight main roots, transplant them to a seed-production nursery and strengthen management, cover with horse manure in November to protect against the cold, and the seeds mature from late May to early June of the following year; select and keep plump, full seeds for propagation the next year. Second, in August, select a sunny, fertile plot for sowing; the seedlings can reach about 30 cm tall in the same year. Before winter, apply sufficient fertilizer and water to promote seedling growth; after greening up the next year, thin the seedlings twice, keeping seedlings at a row spacing of 30-40 cm. They flower in mid-to-late April, and seeds can be harvested in May-June. For any Isatis from which seeds have been harvested, its roots should no longer be used for medicinal purposes.

Pest and disease control

The main disease of Isatis root is downy mildew. This disease harms the leaves. When it occurs, white or grayish-white mold-like matter appears on the underside of the leaves, with no obvious lesions. In severe cases, the leaf sheaths turn brown and even wither. The control method is mainly agricultural control: rational close planting to reduce soil moisture; proper rotation with grass crops when arranging cropping sequences; when diseased plants are found, remove them promptly at the early stage of the disease. Chemical control can also be used. At the early stage of the disease, spray with 1:1:100 Bordeaux mixture. Spray evenly on the leaf surfaces and undersides, once every 7-10 days, for 3 consecutive sprayings; you can also use 65% zineb wettable powder 500-fold dilution for spray control. The main pest harming Isatis root is the cabbage caterpillar, which damages tender leaves. During the larval stage, spray with 90% trichlorfon 800-fold dilution for control.

Harvesting and processing

For those mainly harvesting Daqing leaves, 2-3 cuttings can be taken a year. The first cutting is during the vigorous growth season around Mangzhong, the second before Liqiu, and the third between Chushu and Bailu. When cutting the leaves, choose a sunny day to harvest and dry immediately; green-colored ones are of good quality. If there is cloudy and rainy weather, dry them promptly. For those mainly harvesting Isatis root, do not cut the leaves during the growing period or cut them only once, and dig them up in late October when the aboveground parts wither, avoiding breaking the main root. Dry the dug-up Isatis root in the sun until 60-70% dry, remove the soil, tie into small bundles, and then dry further until fully dry, at which point it is commercial Isatis root.