Planting process and cultivation technology of Isatis indigotica

As an annual or biennial herb, the sowing and harvesting time of Isatis root varies with the season. Generally speaking, Isatis root is suitable for sowing in autumn, early spring or spring, while summer sowing is relatively rare. During the rainy southern rainy season, summer sowing is more suitable, which helps reduce the occurrence of pests and diseases, although this may have a certain impact on yield. In contrast, northern regions are more suitable for sowing later in spring. Let’s learn about the planting process and cultivation techniques of Isatis indigotica.

1. Land selection and preparation

As a deep-rooted plant, the main root of Isatis can reach 40 to 50 cm deep, so it is suitable to be planted in fertile sandy loam with deep soil layer and good drainage. Avoid planting in low-lying or clay soils with poor drainage, as these conditions are not conducive to the growth of Isatis. Before sowing, the land needs to be plowed deeply to a depth of 20 to 30 centimeters and 3,000 to 4,000 kilograms of farmyard manure should be applied as base fertilizer. According to regional differences, flat ridges can be made in the arid northern regions , while high ridges are recommended in the south to facilitate drainage. The ridge width is generally 1.5 to 2 meters and the height is about 20 centimeters.

2. Breeding method

Isatis root is mainly propagated by seeds. The sowing time can be divided into four stages: autumn sowing, early spring sowing, spring sowing and summer sowing according to different regions and purposes. Autumn sowing and early spring sowing mainly harvest seeds, while spring sowing is carried out from April to June. It can harvest both leaves and roots, has a higher yield, and is the most common sowing method. When sowing, draw shallow furrows with a row spacing of 20 to 25 cm and a depth of about 2 cm on the bed surface. After sowing evenly, cover with soil and compact lightly. Watering is required in arid areas.

3. Field management

When the seedlings are 7 to 10 cm tall, thinning is carried out in combination with tillage and weeding, and the final plant spacing is maintained at 6 to 8 cm. After transplanting, apply appropriate fertilizer according to the growth situation. In water-abundant areas or during the rainy season, deep trenches need to be dug to facilitate drainage and prevent root rot. During droughts, water in the morning and evening, avoiding direct sunlight.

4. Pest and disease control

Downy mildew: The disease begins in March and April and is particularly severe during the rainy season. Prevention and control methods include farmland cleaning, crop rotation and the use of 40% ethylene phosphite aluminum spray.

Sclerotinia disease: The disease begins in April and is most severe during the rainy and hot periods from May to June. Prevention and control methods include water-land rotation, increasing the application of phosphorus and potassium fertilizers, and applying lime-sulfur mixture.

Pieris rapae: The larvae damage leaves from May onwards, with the damage becoming more serious in mid-to-late June. It can be controlled by spraying biological pesticide BT emulsion or 90% dichlorodiphenyltrichloroethane liquid.

5. Harvesting and processing

The leaves of spring-sown Isatis root can be harvested 2 to 3 times before the roots are harvested, with the first harvest in mid-June, leaving a stubble of 2 to 3 cm. The second recommendation is to do it in the hot season except in late August to prevent large-scale death. The leaves become medicinal isatis indigotica after being dried. Isatis root should be dug on a sunny day before winter, and the soil, stems and leaves should be removed and dried. The best roots are those that are long, straight, thick, solid and powdery.

As a major Chinese medicinal material , Isatis root has a large year-round demand and relatively low planting costs. The overall yield per mu of Isatis root and Isatis indigotica is quite good, but people should not blindly follow the trend to avoid market saturation.