What are the key cultivation techniques for coix seed
Coix cultivation techniques
Coix seed is the dried kernel of the grass plant Coix lacryma-jobi, also known as coix seed, coix rice, yi mi, six-grain seed, medicinal corn and so on. It has the effects of strengthening the spleen and draining dampness, and clearing heat and discharging pus. It is mainly produced in Jiangsu, Sichuan, Hebei, Liaoning and other provinces, and is cultivated throughout the country.
I. Morphological characteristics
Annual or perennial herb, plant height 1—2 m. Stem erect and stout, with 10—20 nodes, internodes hollow, roots growing from the basal nodes. Leaves alternate, arranged in longitudinal rows; leaf sheath smooth, with a white membranous ligule between it and the leaf blade; leaf blade long lanceolate, apex gradually pointed. Base slightly sheath-like and clasping the stem, midrib obvious. Racemose inflorescence, borne in bundles in the axils of the upper leaf sheaths, spikelets unisexual; the upper part of the inflorescence is the male spike, with 2—3 spikelets at each node, each bearing 2 male florets and 3 stamens; the lower part of the inflorescence is the female spike, enclosed in a bony involucre, usually 2—3 spikelets borne at one node, the female spike has 3 female florets, of which one develops, the ovary has 2 red stigmas extending beyond the enclosing sheath, with degenerated stamens at the base, and when the caryopsis matures, the outer involucre is hard and elliptical. Seed coat red or pale yellow, kernel ovate, elliptical on the back, with a groove in the center of the ventral side. Flowering period July—September, fruiting period August—October.
II. Growth habits
Coix prefers a mild and humid climate, avoids high temperature and muggy heat, is not cold-tolerant, and avoids drought, especially requiring moist soil at the seedling stage, heading stage and grain-filling stage. Seedlings begin to emerge when the temperature is 15°C, and when it is above 25°C with a relative humidity of 80%—90% or more, the seedlings grow rapidly.
The seeds germinate easily, the optimum germination temperature is 25—30°C, and the germination rate is about 85%. The seed lifespan is 2—3 years.
III. Cultivation techniques
1. Site selection and land preparation: Coix does not have strict soil requirements, and can generally be planted in any soil except overly heavy clay. However, it is best to choose a sunny, well-drained sandy loam. Coix has a relatively strong tolerance to salt damage and moisture in saline-alkali land and marshy land, so it can also be planted on seasides, lakeshores, river courses and both sides of irrigation canals. Avoid continuous cropping; the previous crop is preferably legumes, cotton, potatoes and so on. Before land preparation, apply 3000 kg of farmyard manure per mu as base fertilizer. Deep plow and harrow finely, level the land; except for small areas, it is generally not necessary to make beds, but drainage ditches should be opened around the plot.
2. Propagation method: seed propagation, which can be seedling transplanting or direct seeding in the field.
(1) Seed treatment To promote seed germination and prevent smut, seeds should be treated before sowing as follows. 1. Soak the seeds in 5% lime water or 1:1:100 Bordeaux mixture for 24—48 hours, then take them out and rinse them clean with water; 2. Soak the seeds in 60°C warm water for 30 minutes; 3. Mix 0.5 kg of 75% quintozene with 100 kg of seeds.
(2) Sowing: the sowing period varies with variety, generally from March to May; early-maturing varieties can be sown early, and late-maturing varieties can be sown late.
1. Direct seeding in the field by dibbling or drilling. The plant and row spacing for dibbling varies with variety; early-maturing varieties can be denser, and late-maturing varieties can be sparser, generally 25—40 cm × 30—50 cm, sowing 4—5 seeds per hole, sowing depth 3 cm, covering with ash and soil, and watering with diluted manure water, using 4—5 kg of seed per mu.
2. Seedling transplanting. Prepare the seedbed well, broadcast sow for seedlings, cover with a little fine soil, and keep the soil moist; after 30—40 days, when the seedlings are 12—15 cm tall, they can be transplanted, with the same plant and row spacing as direct seeding, planting 2—3 seedlings per hole, and watering with diluted manure water after planting; the seeding rate for seedling raising is 30—40 kg per mu, and the seedlings raised can be transplanted to about 10000 sq m.
3. Field management
(1) Thinning and filling in seedlings: when the seedlings have 3—4 true leaves, thin and fill in the seedlings, leaving 2—3 strong seedlings per hole. For drilled sowing, thin the seedlings to a plant spacing of 3—6 cm. When there are 5—6 true leaves, finalize the seedlings at a plant spacing of 12—15 cm.
(2) Intertillage and weeding: carried out in 3 rounds. The first is shallow hoeing when the seedlings are 5—10 cm tall; the second is carried out when the seedlings are 20 cm tall; the third is carried out when the seedlings are 30 cm tall, combined with fertilization and hilling.
(3) Topdressing: also divided into 3 rounds. The first, when the seedlings are 5—10 cm tall, apply 2000 kg of manure water per mu; the second, when the seedlings are 30 cm tall or at the booting stage, apply 3000 kg of manure water per mu; the third, at the flowering stage, apply a 2% superphosphate solution as foliar topdressing.
(4) Drainage and irrigation: sufficient water should be ensured at the seedling stage, spike stage, flowering and grain-filling stages; in case of drought, water promptly in the evening to keep the soil moist; after rain or furrow irrigation, drain the accumulated water in the furrows.
(5) Removal of basal leaves: after jointing, remove the old leaves and ineffective tillers below the first branch to facilitate ventilation and light penetration.
(6) Artificial supplementary pollination: during the flowering period from 10—12 o'clock, use tools such as ropes to shake the plants so that the pollen flies up, which has an obvious effect on increasing the seed-setting rate.
4. Pest and disease control
(1) Smut: also known as black powder disease, it causes serious damage and has a high incidence rate. Control methods: strictly carry out seed treatment, rotate crops, and immediately pull up and burn diseased plants when found.
(2) Leaf blight: occurs frequently in the rainy season, damaging the leaves. Control methods: at the early stage of the disease, spray with 1:1:100 Bordeaux mixture, or with 65% zineb wettable powder at 500 times dilution.
(3) Corn borer: begins to occur from late May to early June, with serious damage in August—September; at the seedling stage, 1st—2nd instar larvae bore into the heart leaf and eat the leaf mesophyll or veins. At the heading stage, 2nd—3rd instar larvae bore into the stem to cause damage. Control methods: before sowing, clean the field; plant arrowhead around the coix field to trap and kill; at the heart leaf stage, use 0.5 kg of 50% carbaryl powder plus 15 kg of fine soil to make poisonous soil, or use 90% trichlorfon at 1000 times dilution to pour into the heart leaf, or use Bt emulsion at 300 times dilution to pour into the heart leaf.
(4) Armyworm: also known as the night thief worm, the larvae damage the leaves. Control methods: at the larval stage, spray with 50% dichlorvos at 800 times dilution; also use sugar-vinegar poisonous liquid (sugar:vinegar:white liquor:water=3:4:1:27) to trap and kill adults; at the pupation stage, dig the soil to destroy the pupae.
IV. Harvesting and processing
Coix can be harvested in the same year it is planted, and the specific harvest period varies with variety and sowing date. Early-maturing varieties can be harvested in August, while late-maturing ones must be harvested in November. The grains on the same plant also mature unevenly. Generally, when the lower leaves of the plant turn yellow and about 80% of the grains have matured and changed color, they can be harvested. The cut plants can be gathered and stood upright for 3—4 days, then threshed with a threshing machine. The threshed seeds are spread out and sun-dried until dry to obtain shelled coix. It can be stored. Use a shelling machine to hull off the outer shell and seed coat, sieve clean and dry in the sun to obtain coix seed, for medicinal and edible use. V. Seed reservation techniques Before harvesting, select high-yielding individual plants with strong tillering, dense seed set and relatively uniform maturity as seed plants; when the seeds mature, harvest them separately, select by grain, remove variant seeds, seeds with pests and diseases and immature seeds, and keep plump, glossy seeds as propagation seed for the next year.