What are the key operational points of Pinellia pedatisecta (Arisaema) cultivation techniques?
I. Grading of seed tubers
Upon receiving Pinellia pedatisecta seed tubers, immediately empty the bags (spread them out), and divide them into three grades: large, medium and small. Those with a single diameter of 3 cm or more, or several tubers joined together as one, are large seed tubers; those with a single diameter of 1.5-3 cm are medium seed tubers; those with a single diameter below 1.5 cm are small seed tubers.
II. Chemical soaking of seed
Use a 500-fold solution each of thiophanate-methyl + carbendazim (that is, 50 jin of water plus 1 liang of the chemicals), and a 1000-fold solution of avermectin. Prepare the above three chemicals into a solution, and soak the graded Pinellia pedatisecta seed tubers in the solution separately: soak large seed tubers for 24 hours, and medium and small seed tubers for 12 hours, then remove them, air-dry or sun-dry the outer skin (until the outer skin is dry), and they can then be sown or stored.
III. Storage method
Thinly spread the chemical-treated Pinellia pedatisecta seed tubers (with dry outer skin) in a cool, ventilated indoor area at a thickness of 10 cm; during storage keep the temperature between 4-8 degrees, turn them once every 15-20 days, and store until sowing in early spring. If during storage the temperature falls below 4 degrees, they can be put into small bags (20 kg) and placed indoors at above 2 degrees; but if the temperature rises above 8 degrees, spread them out loosely instead of bagging them, to prevent heating from scorching the seed tubers.
IV. Sowing time
In regions where the lowest outdoor temperature in winter is not below -3 degrees, sowing can be done in late autumn in November-December. In other regions, sowing is best done in early spring after the soil thaws; the best time for spring sowing is when the 5 cm soil temperature stabilizes at 8 degrees; soak the Pinellia pedatisecta seed tubers 15 days in advance to promote sprouting (or sow directly without sprouting), and after sowing cover with plastic film (or leave uncovered).
V. Planting method
1. Soil fertilization: For growing Pinellia pedatisecta, sandy loam soil that is loose, fertile, convenient for watering and thoroughly drained must be chosen. After the soil is selected, apply 3000 kg per mu of well-fermented high-quality farmyard manure or human and livestock excrement; if there is no farmyard manure, apply 50 kg per mu of high-quality diammonium phosphate (made in the USA), and according to the soil's fertility additionally apply 10 kg of potassium sulfate and 50-100 kg of superphosphate. Alternatively, apply per mu a mixed fertilizer of 1000 kg of farmyard manure, 40 kg of diammonium phosphate, 10 kg of potassium sulfate and 50 kg of superphosphate. In short, because Pinellia pedatisecta has a high fertilizer demand, sufficient base fertilizer must be applied.
2. Soil treatment: If there are underground pests in the soil, such as mole crickets and cutworms, use phoxim granules or other pesticides for killing underground pests when plowing. If the previous crop was cotton, vegetables or other crops prone to disease, also apply pesticides for killing soil-borne pathogens when plowing, such as thiophanate-methyl, carbendazim and so on.
3. Sowing method: (1) After soil fertilization, sterilization and pest elimination by plowing, make raised beds 80-120 cm wide, ready for sowing. (2) First cut the large Pinellia pedatisecta seed tubers and the joined tubers into several individual seed tubers with a knife; when cutting, make sure each cut seed tuber has a bud eye; as you cut, place them in sunlight to dry the cut surface until no liquid remains, then sow immediately, and do not leave them for long. (3) Sow large (including cut), medium and small seed tubers separately, one seed tuber per hole; sow the large ones first: large seed tubers at a row spacing of 25 cm, plant spacing of 15 cm, and depth of 5 cm; medium seed tubers at a row spacing of 20 cm, plant spacing of 10 cm, and depth of 4 cm; small seed tubers broadcast at a row spacing of 20 cm and a depth of 2-3 cm; after broadcasting, spread the small seed tubers evenly, keeping a plant spacing of about 3-5 cm. After sowing is complete, cover with soil level with the ground, then spray the herbicide "acetochlor" to seal the soil, and after spraying cover with plastic film (or leave uncovered).
VI. Field management
1. Water: From seedling emergence in the early stage until before the high temperatures of June, keep water sufficient, do not let it dry out, eliminate weeds, and cultivate and loosen the soil. From June onward, in the mid-to-late growth stage, do not apply large amounts of water; if the soil is severely dry, you may water lightly or water in furrows along with cooling, and pay attention to timely drainage after rain and spraying fungicides (to prevent disease), keeping the soil alternately moist and dry; at this stage the soil must never be too wet, otherwise it is prone to rot disease.
2. Light: Use tall-stalk crops or other plants for shade; in the season of high temperature and strong light, maintain about 60% light, with the focus on June-August. Before June and after August, no shading is needed.
3. Temperature: When the air temperature is above 30 degrees, use local conditions to cool down, such as spraying well water.