Detailed Explanation of Key Techniques for High-Yield Cultivation of Coix Seed

Coix SeedAlso known as Yuzhuzhu, Liuguzi, and Medicinal Corn, it is an annual herbaceous medicinal plant of the grass family (Poaceae), with the kernel used as medicine. It has effects such as clearing heat, promoting diuresis, resolving dampness, expelling pus, tonifying the lungs, strengthening the spleen and stomach, strengthening bones and muscles, and lowering blood pressure, and it also has a good anti-cancer effect. Coix seed is both a medicinal and edible tonic Chinese medicinal herb, and a commonly used raw material for health product manufacturers to make summer cooling drinks. In recent years, not only has domestic market demand increased, but it is also exported to Japan, South Korea, and other places. Coix is one of the short-cycle, affordable, and quick-return medicinal herb varieties, and can be planted in both northern and southern parts of China. The key points of its high-yield cultivation are introduced as follows.

I. Selection of Improved Varieties

Coix varieties are divided into three types: early-maturing, mid-maturing, and late-maturing. Among them, “Thin-Shell Red Coat” coix is a mid-maturing hybrid improved variety bred in recent years. Its characteristics are: oval fruit, light brown surface, light red or pale white inner seed coat, thin seed shell, 65% milling yield, thick and sturdy stems, strong lodging resistance, high yield, and relatively uniform maturity. It is the best variety to choose for planting.

II. Land Selection and Preparation

Coix has strong adaptability, is not demanding on soil, prefers moisture, and is tolerant of salinity and poor soil. Traditionally, land with good sun exposure, deep soil layers, gentle slopes, hillsides, and flat land is preferred for planting, and waterlogging should be avoided. When preparing the land, first apply 1500 kg of farmyard manure and 50 kg of superphosphate per mu, then plow, harrow finely and level, and open drainage ditches around the perimeter, ready for sowing.

III. Seed Treatment Before Sowing

To prevent the relatively common smut disease, seeds should be disinfected before sowing. Put the seeds in a cloth bag, soak them in warm water at 30°C-40°C for 10-15 minutes, remove them, and then immerse them in 2% lime water for 24 hours; they can also be soaked in 1:1:100 Bordeaux mixture for 24 hours. After removal, rinse them clean with water immediately, and they are ready for sowing. In addition, at sowing time, pesticides such as 50% carbendazim or 50% thiophanate-methyl can be used to dress the seeds at 0.4%-0.5% of the total seed weight, with good disease prevention results.

IV. Sowing

Coix can be planted in both spring and summer, but no later than the end of June. Sowing methods are divided into drilling and dibbling. Drilling: on the prepared ground, open shallow furrows 3-4 cm deep at a row spacing of 35-40 cm, evenly scatter the seeds into the furrows, and cover with fine soil or soil-manure mixture, just enough to cover the seeds. Dibbling: on the prepared ground, dig holes at a row spacing of 40-45 cm and a plant spacing of 15-20 cm, with a hole depth of 5-6 cm, sow 3-4 seeds per hole, and then cover with soil level with the hole surface. The sowing rate is 3-4 kg per mu.

V. Field Management

1. Thinning and Final Spacing In directly sown fields, when the seedlings grow 2-3 true leaves, remove crowded seedlings and diseased or weak seedlings while weeding, keeping the plant spacing of drilled seedlings at 5-7 cm; when the seedlings grow 5-6 true leaves, finalize the spacing, keeping a plant spacing of 10-15 cm. If there are gaps, replant in time.

2. Cultivation and Weeding Begin one cultivation and weeding at thinning; carry out another at final spacing; afterward, do so according to soil compaction and weed growth in combination with topdressing. During the growing period, use benzoic acid herbicides such as dicamba (Banvel) for stem and leaf treatment, which can control annual or perennial broadleaf weeds.

3. Topdressing Generally, topdress 2-3 times during the growing process. The first topdressing is carried out when the seedlings are 4-7 cm tall, applying 5-10 kg of ammonium sulfate per mu, or 1000 kg of decomposed human and livestock manure and urine, to promote seedling growth and early and multiple tillering; the second topdressing should depend on seedling condition and soil fertility, generally at the early jointing stage, when the main stem has 11-12 leaves, applying 10-15 kg of ammonium sulfate per mu or 1500 kg of decomposed human and livestock manure water, to promote robust plant growth and benefit booting; the third topdressing should depend on seedling condition and soil fertility, applying ear-promoting fertilizer, with 3-5 kg of urea per mu or 0.3% potassium dihydrogen phosphate solution as a foliar spray, to promote full grains and improve quality and yield.

4. Removing Lower Leaves After coix joints, remove the old leaves below the first branch and ineffective tillers, which is beneficial for ventilation and light penetration, promotes thick and sturdy stems, and also has a certain effect on preventing lodging.

5. Artificial Supplementary Pollination Coix flowers are unisexual. Although male and female spikelets are on the same plant, pollination relies on wind. However, during the flowering period when there is no wind or the wind is weak, the female flowers cannot be fully pollinated, resulting in empty and shriveled grains. During the full flowering stage, artificially shaking the stems to make pollen drift can be used to increase the seed-setting rate and increase yield.

VI. Pest and Disease Control

1. Smut disease damages the ear. After the affected seeds rupture, they release a large amount of dark brown powder. Control methods: ① soak and disinfect seeds before sowing; ② when diseased plants are found, pull them out immediately, burn them or bury them deeply; ③ disinfect the diseased holes with 5% lime milk.

2. Leaf blight damages the leaves. After occurrence, pale yellow lesions appear on the leaves. Control methods: ① spray 1:1:100 Bordeaux mixture at the early stage of disease, once every 7 days, spraying 2-3 times in succession; ② remove lower leaves in time to maintain ventilation and light penetration in the field.

3. Armyworm The larvae bite and eat the leaves. Control method: spray with 800-1000 times dilution of 90% trichlorfon.

VII. Harvesting and Processing

Coix is harvested about 5 months after sowing. When the stems and leaves turn withered and yellow and 80% of the fruits are light brown and mature, cut the plants together with the stems, thresh with a threshing machine, sun-dry, remove impurities, winnow away empty shells, sift clean, then use a rice milling machine to remove the outer shells, sift clean again and sun-dry, and it becomes the commercial product.