When to plant Isatis root?

Isatis root is a commonly used Chinese medicinal material . Its dried roots and leaves have medicinal value. This plant is widely cultivated in China. As a biennial herb, the plant height of Isatis indigotica is generally between 40 and 120 cm. Its main root is long cylindrical, fleshy, gray-yellow in color, and rich in medicinal ingredients. So when should Isatis root be planted?

1. Growth habits

Isatis root is a highly adaptable plant that can tolerate cold and prefers warm climates, but does not like humid environments. For normal growth and development, Isatis needs to experience a low temperature period in winter to promote flowering and seeding. The seeds of Isatis indigotica germinate easily in the temperature range of 15°C to 30°C, with a germination rate of over 80%, and the seed lifespan is generally one to two years.

2. Site selection and land preparation

The taproot of Isatis can grow very deep, so it should be planted in fertile sandy loam with deep soil and good drainage. The growth of Isatis indigotica will be adversely affected in low-lying areas or clay soils with poor drainage. Before sowing, the land should be plowed deeply to a depth of 20 to 30 centimeters. Sandy land can be plowed a little shallower. Apply sufficient base fertilizer, mainly farmyard manure, at a rate of 3,000 to 4,000 kilograms per mu. After turning the soil, break up the clods and harrow it flat to make the bed surface. In the northern areas with little rainfall, flat ridges can be made, while in the south, high ridges should be made to facilitate drainage. Generally, the ridges are 1.5 to 2 meters wide and about 20 centimeters high.

3. Reproduction method

Isatis root is mainly propagated by seeds.

Sowing time: The sowing season of Isatis root is different, and the harvested products are also different. The sowing season can be divided into four stages: autumn sowing, early spring sowing, spring sowing and summer sowing. The main purpose of autumn sowing and early spring sowing is to harvest seeds, and the roots of Isatis indigotica planted in these two periods are not suitable as medicinal materials. Summer sowing is suitable for areas in the south with a longer rainy season. It can reduce pests and diseases, but the yield is lower. The isatis root sown in spring from April to June can be harvested as both leaves and roots, and the yield is relatively high. It is the most common sowing method.

Sowing method: When sowing, make shallow furrows about 2 cm deep on the bed surface with a row spacing of 20 to 25 cm, sprinkle the seeds evenly into the furrows, cover with about 1 cm of soil and gently compact. In dry areas, water appropriately. Under suitable temperatures, seedlings will emerge 7 to 10 days after sowing.

4. Field management

When the seedlings are 7 to 10 cm tall, thinning should be carried out in combination with tillage and weeding, and finally the seedlings should be planted at a spacing of 6 to 8 cm. After transplanting, apply human manure or chemical fertilizers appropriately according to the growth of the plants. In water-abundant areas or rainy seasons, deep trenches should be dug to facilitate timely drainage and avoid root rot. In dry weather, watering should be done in the morning or evening, avoiding strong sunlight.

5. Pest and disease control

Downy mildew: It begins to occur frequently from March to April, especially in the rainy season in spring and summer, and mainly harms the leaves. Prevention and control methods include: cleaning the fields and treating diseased plants to reduce pathogens, crop rotation, and spraying 40% ethylene phosphite aluminum at 200 to 300 times dilution, once every 7 days for 2 to 3 times.

Sclerotinia disease: It starts in April and becomes more serious during the rainy and hot periods from May to June. It is transmitted from the soil, with the base leaves becoming infected first and then spreading upward to damage the stems, stem leaves and fruits. Prevention and control methods include: water-land rotation or rotation with gramineous crops, increasing the application of phosphorus and potassium fertilizers, and applying a lime-sulfur mixture to the base of the plants.

Pieris rapae: Its larvae are commonly known as cabbage loopers. They start to damage leaves from May, and are particularly serious from early to late June. You can use biological pesticide BT emulsion, 200 to 250 grams per 1,000 square meters, or spray 800 times of 90% trichlorfon solution for prevention and control.

6. Harvesting and processing

The leaves of spring-sown isatis root can be harvested 2 to 3 times before the roots are harvested. The first time is in mid-June, when the seedlings are about 20 cm tall, leaving 2 to 3 cm of stubble to facilitate the growth of new leaves. The second time is in late August. Avoid harvesting during the high temperature season to avoid causing large-scale death. The harvested leaves are dried to become medicinal Isatis indigo leaves . The best leaves are those that are large, less broken, clean, dark green in color, and have no moldy smell. Isatis root should be dug on a sunny day before winter, and be sure to dig deep to prevent the roots from being cut. After digging up the soil, remove the dirt, stems and leaves, spread it out to dry until it is 70% to 80% dry, tie it into small bundles, and then dry it again until it is completely dry. The best roots are those that are long, straight, thick, solid and powdery.

The above is an introduction to the planting time and method of Isatis root. There are many aspects that require attention when planting Isatis root, and you cannot plant it blindly.