Detailed Explanation of Standardized Cultivation and Management Techniques for Root Mustard

Mustard (Brassica juncea) is an annual or biennial herbaceous plant of the genus Brassica in the family Cruciferae (Cruciferae). It is a famous specialty vegetable of China, originating in China, and is a commonly cultivated vegetable throughout the country, mostly distributed in the provinces south of the Yangtze River. The main and lateral roots of mustard are distributed within about 30 cm of the soil layer; the stem is a shortened stem, and the leaves are borne on the shortened stem, with shapes such as elliptical, ovate, obovate, and lanceolate, and leaf colors of green, dark green, light green, yellow-green, green with stripes, or purplish red. It is rarely cultivated in European and American countries and originated in Asia. Li Shizhen's "Compendium of Materia Medica" recorded the medicinal value of mustard.

Mustard prefers cool, moist conditions, avoids heat and drought, and is slightly tolerant of frost. The average temperature suitable for seed germination is 25°C. The average temperature most suitable for leaf growth of mustard is 15°C, and the temperature most suitable for the growth of the edible organs is 8-15°C, but the formation of the edible organs of stem mustard and heading mustard requires lower temperatures; generally, leaf mustard has less strict temperature requirements.

Mustard also has high nutritional value in terms of how it is eaten. Adding a little mustard to a salad will give it some spiciness, but it should not be used too much because its texture is coarse and its flavor is strong. To remove some of the flavor, it can be blanched in boiling water before cooking. Mustard can be paired with barley, black rice, buckwheat, potatoes, and beans, and it also tastes quite good when made with sauces or bread paste. Mustard can be cooked by steaming, boiling, or stir-frying. After pickling, mustard has a delicious flavor, can increase appetite, and promotes gastrointestinal digestion. Adding mustard when making soup can give the dish a slight spiciness. Mustard tuber contains dietary fiber, which can promote gastrointestinal peristalsis. In addition, mustard is an excellent dietary remedy for eye patients.

Standardized Cultivation and Management Techniques for Root Mustard

1) Cultivation Season

Root mustard is sown in autumn in both the north and the south. In areas where autumn temperatures drop quickly and winters are severely cold, autumn sowing is earlier; in areas where temperatures drop more slowly and winters are not very cold, autumn sowing is later. From North China to the Yangtze River basin and south of the Yangtze River, the sowing period can range from around August 5 to around September 5. Sowing too early tends to cause premature bolting; sowing too late results in insufficient vegetative growth in the early stage, affecting yield and quality, and in colder areas the plants may suffer frost damage before harvest. In high-cold regions such as Northeast China, the growing season is too short, so spring sowing is mostly practiced.

2) Sowing and Seedling Raising Root mustard can be direct-sown, but in the Yangtze River basin seedling transplantation is the main method. Direct-sown plants have fewer branches on the fleshy root and a more uniform shape; transplanted plants develop more branches, but centralized management is more convenient and the land can be fully utilized. To reduce branching of the fleshy root, the method of transplanting early with soil attached can be used. For direct sowing, when the soil is dry, dig holes 2 cm deep for hill sowing, then cover with soil and irrigate. When the soil is moist, do not dig holes; sow in hills according to row and plant spacing, then rake the seeds into the soil with a rake. The sowing rate is about 1500 grams per hectare. Root mustard seeds are small, so the soil cover should not be too deep. Seedlings from direct sowing can also be transplanted to the main field. The seedling bed should be loam soil with good water and fertilizer retention. Half a month before sowing, plow 20 cm deep, apply 37500 kg of organic fertilizer, 600 kg of superphosphate, and 3000 kg of plant ash per hectare as base fertilizer, then finely prepare and level the soil before sowing, and make raised beds 130 cm wide and 15 cm high. Broadcasting seeds at 4.5-6 kg per hectare can provide seedlings for 15 hectares of main field planting. After sowing, cover with sieved compost, just enough to hide the seeds, then water, and cover with rice straw to prevent heavy rain and drought. Remove the cover promptly after emergence. Thin the seedlings once each when there are 2-3 true leaves and 3-4 true leaves, removing weak seedlings and inferior seedlings with pests or diseases, with a seedling spacing of 6 cm. After thinning, apply dilute liquid fertilizer and control aphids 3 times. Growing strong, disease-free seedlings with a compact plant shape is the foundation for high yield and good quality.

3) Land Preparation and Field Planting Root mustard has no strict requirements for soil, but clay loam rich in organic matter with good water and fertilizer retention is best. Although root mustard likes a moist environment, when cultivated on soil with a high groundwater table, the fleshy root grows poorly, has a higher water content, and has poor processing quality, so a plot with good drainage and aeration should be selected. Before planting, plow the land 20-30 cm deep and make beds 1.5-2 m wide and 15 cm high. Depending on the spread of different varieties, the row spacing is 37-47 cm and the plant spacing is 33-40 cm, generally planting 45000-52500 plants per hectare. If planted too densely, fleshy roots smaller than 250 grams are not suitable for processing. When the seedling age is about 30 days and there are about 5 true leaves, transplant. At that time, the slightly swollen fleshy root can already be seen. Water before transplanting so that seedlings can be taken with soil. When transplanting, place the taproot of the seedling vertically in the center of the planting hole, and do not bury soil above the shortened stem, so that the root is not twisted or damaged, and the fleshy root can grow uniformly in the future with few branch roots. Root mustard requires sufficient fertilizer. Because the fleshy root is the main product, in addition to mainly applying nitrogen to promote leaf and root growth, phosphorus and potassium fertilizers should especially be applied in combination. As base fertilizer, apply 37500 kg of compost, 600 kg of superphosphate, and 3000 kg of plant ash or 300 kg of potassium chloride per hectare.

4) Field Management Topdressing for root mustard follows the principle of light, heavy, light. The first application, after the plants survive transplanting or after direct sowing is thinned to a stand, applies 15000 kg of dilute livestock manure plus 75 kg of urea per hectare to promote the formation of a strong leaf rosette. The second application, when the leaves and fleshy root grow rapidly, uses 15000 kg of thicker livestock manure water plus 225 kg of urea; the timing of this fertilization is about late October. The third application depends on seedling growth and applies thicker livestock manure as appropriate; if growth is very vigorous, no more fertilizer is needed. The 3 applications use a total of 4000-5000 kg of livestock manure. Topdressing is applied 1 month before harvest. The budding, bolting, and flowering of root mustard do not have strict low-temperature requirements, and premature bolting often occurs before the end of the year. In particular, early-maturing varieties sown too early are prone to premature bolting, affecting the yield and quality of the fleshy root, so pinching should be done as early as possible, removing flower buds or cutting off the flower stalk with a sharp knife close to the base, with the cut slightly slanted to prevent water accumulation and rot. Pinching too late affects the quality of the processed product.

5) Harvest In areas with heavy winter frost, root mustard cannot overwinter in the open field and must be harvested before frost. North China has severe winter cold, earlier autumn sowing, and a relatively short total growth period, generally only about 90 days, so it should be harvested from late October to early-to-mid November. In warmer areas such as Yunnan and Sichuan, early-maturing varieties have a growth period of about 120 days, mid-maturing varieties about 130 days, and late-maturing varieties about 140-150 days. Generally, late December to early-to-mid January is the suitable harvest period. The sign of maturity is that the basal leaves turn orange-yellow, the root crown changes from green to yellow, and lateral branches sprout from the leaf axils or flower buds first appear; at this time, harvest promptly. If harvesting is too late, the epidermis thickens, fiber increases, and bolting or hollowing occurs, affecting processing quality. After digging up the fleshy root, cut off the lateral roots, and according to processing needs either remove all leaves or keep a few green leaves, then handle according to processing requirements. Generally, the yield is about 30000 kg per hectare.

Supplement: Fertilization Techniques for Root Mustard

1. Application of base fertilizer. Root mustard likes land rich in organic matter, so before land preparation, a sufficient amount of organic fertilizer must be applied. Generally, farmyard manure or composted urban waste can be used, then plant ash and superphosphate added. The specific amount depends on soil fertility. Generally, per 667 square meters, use 3500-4000 kg of farmyard manure, 150 kg of plant ash, and 25 kg of superphosphate, spread evenly over the ground, then plow into the soil to a depth of 40-50 cm, level with a rake, and make beds. 2. Application of topdressing. During the growth and development period of direct-sown root mustard, topdressing can be applied 5 times depending on the specific situation. After the cotyledons of the seedlings unfold, carry out the first topdressing, applying 500 kg per 667 square meters of dilute manure urine with a manure-to-water ratio of 1:7. After the first thinning, during intertillage and weeding, apply the second topdressing, using manure urine water at a ratio of 1:5 at 800 kg per 667 square meters. After the seedlings are thinned to a stand, the plants grow rapidly and need sufficient fertilizer and water, so the third topdressing can be carried out, applying 10-15 kg of ammonium sulfate per 667 square meters. After entering the rosette stage, to promote fleshy root enlargement, the fourth topdressing can be applied, using 10 kg of urea and 4 kg of potassium sulfate per 667 square meters. When entering the peak period of fleshy root enlargement, add the fifth topdressing, which can accelerate fleshy root enlargement and increase yield; this time use a nitrogen, phosphorus, and potassium compound fertilizer at 15-20 kg per 667 square meters. Topdressing should be applied early and combined with phosphorus and potassium fertilizers. If topdressing is too late and nitrogen is excessive, the aboveground part will grow too vigorously and affect fleshy root enlargement. 3. Application of foliar fertilizer. Root mustard needs more boron during growth. Entering the seedling stage, foliar spray can be applied with 0.1%-0.25% borax or boric acid. In the early growth stage, a 0.02%-0.05% ammonium molybdate aqueous solution can be sprayed. After the root shoulder is exposed, spray 2% superphosphate on the leaves once a week, which has a significant yield-increasing effect.