Detailed Tutorial on the Latest Cultivation Techniques and Methods for Coix Seed
Coix seed (Coix lacryma-jobi) is an annual herb of the grass family. The mature dried kernel of coix seed, originally known as coix seed kernel, also called coix seed or Job's tears, was first recorded in the Shennong Bencao Jing and listed as a top-grade herb. In the past it was mainly produced in Pucheng and Putian in Fujian, and called Pumi ren; in recent years it has also been planted on a large scale in Anguo and Fuping in Hebei and Fuyang and Zhuanghe in Liaoning, where it is respectively called Qimi ren and Guanmi ren. Now it is cultivated in all provinces across the country.
Coix seed contains fatty oil, coixol, sterols, amino acids, vitamin B1, and coixenolide. It can promote diuresis and drain dampness, help clear heat and expel pus, treat muscular rheumatism, and also strengthen the spleen and stop diarrhea. It is sweet in flavor and cold in nature, entering the spleen, stomach, and lung meridians. It mainly treats edema and beriberi, poor appetite and diarrhea, damp arthralgia with contracture, lung abscess, and intestinal abscess; as an auxiliary drug, it can be used for diuresis and anti-inflammation, removing dampness and relieving pain, and strengthening the spleen and stopping diarrhea.
Growing Environment
Coix seed prefers a warm and humid climate. It can be cultivated on flat land or slopes below 1200 m altitude, and is especially suitable for sunny sites that are easy to irrigate. During the heading and flowering stage, it is most afraid of drought; not only are there fewer grains and more empty shells, but the grains are also not plump. The most suitable soil is fertile, moist, neutral or slightly acidic clay loam with good water retention. Dry, barren sandy soil and soil with poor water and fertilizer retention are unfavorable for growth. When grown in overly loose and fertile sandy loam, the stems and leaves flourish, but in summer and autumn it often lodges easily, and the stems and leaves tend to grow excessively, resulting in fewer grains. Continuous cropping is not suitable, nor is it easy to use grass-family crops as the preceding crop. Cultivation in paddy fields can increase yield.
Cultivation Methods
1. Land preparation
After the preceding crop is harvested, prepare the land in time. First plow deeply, about 30 cm deep. During deep plowing, apply compost or mixed fertilizer, about 2000 kg per mu. Before spring sowing, plow once more, harrow finely and level, and make beds 1 to 3 m wide. If planting on hillsides, beds are generally not made, but drainage ditches and hillside retention dikes should be opened well to prevent rain from washing the soil during the rainy season.
2. Sowing
Seed treatment. Smut is the main disease of coix seed. To prevent damage, seeds must be treated before sowing. There are three commonly used methods: (1) Boiling water seed soaking: soak the seeds in clean water overnight, put them into a bamboo basket, drag the basket through boiling water while stirring quickly so that all seeds are scalded. The immersion time is about 5 to 8 seconds, then immediately spread them out, air-dry the moisture, and sow. Do not treat too many seeds at one time, to avoid some seeds not being scalded. The scalding time must not exceed 10 seconds, to prevent the seeds from being scalded to death and failing to germinate. (2) Quicklime seed soaking: soak the seeds in warm water at 60 to 65°C for 10 to 15 minutes, remove the seeds, wrap them in cloth, press them down with a heavy object into 5% quicklime water, and soak for 24 to 48 hours. Take them out, rinse with clean water, and sow. (3) Soak the seeds in 1:1:100 Bordeaux mixture for 24 to 48 hours, then sow. To avoid missing plants caused by birds pecking after sowing, poison bait can be mixed with the seeds before sowing.
Sowing period. Mostly at the Spring Equinox (mid to late March). In higher altitude areas, mostly during Qingming to Guyu (early to mid April). In places with summer drought, sow as early as possible. If too late, germination will be fast, and severe yield reduction will occur due to summer drought.
Sowing method. Dibbling is usually adopted, with a hole spacing of 30 cm and a hole depth of about 6 cm. Sow 6 to 8 seeds per hole, using 4 to 6 kg of seed per mu. After sowing, apply 300 to 400 kg per mu of wood ash mixed with human and animal manure and urine into the holes, then cover with soil level with the ground.
Field Management
1. Thinning and final stand establishment. Thin when the seedlings have 3 to 4 true leaves, leaving 4 to 5 plants per hole. In large-scale production, if the seed rate can be controlled and full emergence can be ensured, thinning may not be necessary.
2. Cultivation and weeding. Usually carried out three times. The first time is combined with thinning; the second time, when the seedlings are about 30 cm tall, hoe shallowly, and pay special attention not to damage the roots; the third time, when the seedlings are 50 cm tall and the plants have not yet closed the rows, be careful not to break the seedling stems, and hill up soil at the right time to avoid lodging later.
3. Fertilization. In the early growth stage, to promote seedlings, focus on applying nitrogen fertilizer; in the later stage, to promote sturdy stems and booting, apply more phosphorus and potassium fertilizer. At the first cultivation and weeding, apply 1000 to 1500 kg per mu of human and animal manure and urine, or 10 kg of ammonium sulfate; before the second cultivation and weeding, use 100 kg of wood ash mixed with human manure and urine, open holes 10 cm away from the plants and apply, then cover with soil during cultivation; the third time, before flowering, spray a 1% to 3% superphosphate solution on the leaves, with the amount of superphosphate controlled at 7.5 to 10 kg per mu.
4. Watering. If spring drought occurs after sowing coix seed, irrigate in time to support germination. During jointing, booting, and flowering, if there is no rain for a long time, irrigation should also be given to prevent insufficient soil moisture, incomplete grains, and empty shells. In the rainy season, also pay attention to draining accumulated water.
5. Artificial supplementary pollination. Coix seed is wind-pollinated, and male flowers are few. Under windless conditions, if the female flowers are not all pollinated, shriveled grains easily appear. Two people can pull a rope across the tops of the stems, shaking the plants so that pollen spreads to the female flowers, once every 3 to 5 days, until flowering ends.
6. Selection and breeding of superior seed. To prevent or delay variety mixing, degeneration, and the spread of smut, selecting and breeding superior seed is the basis for ensuring high yield. Coix seed has two varieties, tall-stalk and short-stalk. The short-stalk type has a plant height of 0.7 to 1.3 m, more tillering, a shorter flowering period, denser fruiting, earlier maturity, and higher yield, and is suitable for seed retention. Especially in areas with lower altitude and frequent summer drought, early-maturing short-stalk varieties should be selected for cultivation. Before harvest, select in the field individual plants that are short in plant type, robust in growth, have many and large spikes, and are disease-free, harvest them separately, dry them in the sun, winnow them clean, and store them as seed. It is also possible to select a certain area meeting the plant selection standard and harvest it separately for seed. For large-scale planting areas, seed fields specially for propagating improved varieties should be established. According to the requirements for seed retention and selection of superior seed, sow the seeds obtained by plant selection in the next year's seed field, and the seeds harvested from the seed field are used for sowing in the next year's main field.
Pest and Disease Control
1. Diseases
(1) Smut. Also called black powder disease, it mainly damages the spike. The pathogen spores attached to infected seeds reach the spike as the plant grows, causing newly set seeds to swell into spherical or oblate brown galls. After rupture, a large amount of black powder (the pathogen spores) is released and continues to infect. When damage is severe, the disease rate can reach more than 90%, or even result in no harvest at all. Control methods: pay attention to seed selection and seed disinfection treatment; persist in half-year field single-plant seed selection, and where conditions permit, establish disease-free improved seed fields; since coix seed has strong fertilizer absorption and smut is severe, rotation should be practiced and continuous cropping avoided. The preceding crops should preferably be beans, cotton, potatoes, and the like.
(2) Leaf blight. It damages the leaves, showing small pale yellow spots, and the leaves turn yellow and withered. In the early stage of the disease, spray 1:1:100 Bordeaux mixture, or 65% wettable zineb 500-fold solution.
2. Insect pests
The main insect pests are armyworm and corn borer. Armyworm larvae damage leaves, biting them into irregular notches, and also damage tender stems and tender spikes. When outbreaks occur, the leaves can be eaten bare. Control methods: spray 50% dichlorvos 800-fold solution during the larval stage, and use sugar-vinegar poison liquid to trap and kill adults; to fundamentally eliminate armyworm, dig the soil to destroy pupae. Corn borer first- and second-instar larvae bore into the young leaf whorl of seedlings and eat the leaf flesh or veins; at the heading stage, second- and third-instar larvae bore into the stems and cause damage, boring into dead heart or white spikes, which break and droop in wind. Control methods: burn corn and coix seed stalks in early spring to eliminate overwintering larvae; use black light lamps at night in May and August for trapping and killing; when the heart leaves unfold, pour 200-fold borer-killing powder solution into the heart leaves; planting canna around the field can also trap and kill them.
Harvesting and Processing
1. Harvest. The harvesting period varies with variety and region. Early-maturing varieties: from Minor Heat to before Start of Autumn (July to early August); medium-maturing varieties: from End of Heat to White Dew (late August to mid September); late-maturing varieties: from Frost's Descent to before Start of Winter (late October to mid November). In the south, generally at White Dew (early to mid September); in the north, generally at Cold Dew (early October). The suitable harvest time is when 80% of the fruits are mature. It must not be too late, to avoid yield reduction from shedding of mature seeds. When harvesting, choose a sunny day to cut the whole plant or only the upper part of the stems, and thresh with a threshing machine or after drying in the sun.
2. Processing. After threshing, dry in the sun, winnow or blow away impurities, and use a rice milling machine to remove the outer shell and seed coat from the clean seeds. After screening or winnowing clean, it becomes the commercial medicinal material.
3. Quality identification. Coix seed is oval or elliptical, slightly flat at the base and bluntly rounded at the tip. The surface is milky white and smooth. A small amount of light brown seed coat often remains. The base is concave, with a dot-like hilum in the center, and a ventral groove on the side, light brown within the groove. When cut lengthwise along the direction of the ventral groove, the endosperm is relatively large, white and farinaceous, the scutellum is narrow and long, light yellow, and the embryo is slender, located on one side of the ventral groove, with the radicle at the upper end and the plumule at the lower end. The cross-section of the kernel is kidney-shaped, hard in texture, and sweet in taste. Those with large grains, white color, integrity, no broken grains, and no powder or impurity fragments are considered best.
4. Storage and preservation. Coix seed is prone to insect damage and mold during storage. It should be stored in a ventilated, cool, and dry place, and dried in the sun at the right time and roasted regularly.