Detailed Explanation of Key Points for Standardized High-Yield Cultivation Techniques of Polygonum multiflorum
(1) Arranging Suitable Soil and Crop Rotation
Polygonum multiflorum (He Shou Wu) is not very demanding regarding soil; it can be planted in general soil, but loamy soil with relatively high fertility, a high groundwater table, and good irrigation and drainage conditions is preferable. As for crop rotation, it can be spring-planted, intercropped in wheat rows, or transplanted after wheat harvest, but spring planting gives the highest yield and the best quality.
(2) Selecting and Keeping Good Seed Roots
When digging and harvesting in the previous year, take care to select disease-free, frost-damage-free, undamaged, robust and plump main root tubers as seed roots. Keep enough seed roots at 70-80 kg per mu of field, and store the seed roots in a cellar to overwinter. The cellar should be dug in a wind-sheltered, sunny place with dry terrain. For large storage volumes, the cellar can be built in the style of a sweet potato cellar; for small storage volumes, a small earthen cellar 1.5 m deep and 1.5 m wide can be dug, with the length determined by the storage volume.
(3) Applying Sufficient Base Fertilizer and Preparing the Land Finely
Base fertilizer should be mainly organic fertilizer, supplemented with phosphorus and potassium fertilizers, with little or no nitrogen chemical fertilizer. Before land preparation, apply 3-5 cubic meters of farmyard manure, 40-50 kg of superphosphate, and 15-20 kg of potassium sulfate per mu. For spring-planted winter fallow fields, winter plowing for freezing and soil weathering should be carried out before winter, and after the beginning of spring, plowing and harrowing should be done in combination with base fertilizer application. For wheat-row intercropping, intercropping ridges should be reserved when sowing wheat, with an empty width of no less than 30 cm, and the base fertilizer should be applied when manually ridging and turning the soil.
(4) Sowing at the Appropriate Time
The earliest sowing time should be when the average temperature stably passes above 10°C. In Xuzhou, spring sowing is generally in early April. Both wheat-row intercropping and post-wheat planting should adopt seedling raising and transplanting, so that late stubble does not mean late seedlings. Because of the local climate, Polygonum multiflorum cannot set seed here and relies on seed root propagation. Before sowing, soak the seed roots in clean water for 0.5-1 hour, then cut them into small root pieces 3 cm long. When sowing, in pure-crop fields, open furrows along a line, with a furrow depth of about 6 cm, a row spacing of 30-35 cm, and a hill spacing of 20-25 cm, at 6000-8000 hills per mu. After sowing, cover with soil, press to preserve moisture, or cover with plastic film. In intercropping fields, set hills according to rows, and after sowing, cover with soil and firm it. For Polygonum multiflorum after wheat stubble, seedling raising and transplanting should be used, which helps achieve early, complete, and strong seedlings. After transplanting, if the soil moisture is insufficient, irrigation must be carried out to create adequate moisture and ensure complete seedling establishment.
(5) Timely Field Management
Polygonum multiflorum has a long seedling stage and closes its rows late, so it is prone to weeds. After emergence, hoe and loosen the soil early, and then loosen and hoe again as needed. When the main stem vine grows to more than 30 cm, soil loosening and hoeing can be stopped. In topdressing, the principle should be to apply seedling-promoting fertilizer early, apply growth-promoting fertilizer lightly, and apply tuber-expanding fertilizer heavily. In fields with insufficient base fertilizer, apply a quick-acting nitrogen chemical fertilizer once after complete seedling establishment, generally 5-8 kg of standard nitrogen fertilizer per mu. When the main stem vine grows to 6-8 nodes and has 3-4 branches, apply a growth-promoting fertilizer once, generally 15 kg of standard nitrogen fertilizer per mu. When the root tubers are in the elongation and expansion stage, apply root fertilizer, mainly phosphorus and potassium fertilizers, generally 8-10 kg of potassium dihydrogen phosphate per mu. Polygonum multiflorum is a climbing plant, and adding supports can improve light transmission in the field, increase photosynthetic efficiency, and prolong the functional period of the basal leaves. Generally, in the late growth-promoting stage, insert 500-600 branches per mu to let the vines climb. Pests must be well controlled, mainly Chinese leafhoppers, aphids, red spider mites, and others. In particular, the Chinese leafhopper is a devastating pest of Polygonum multiflorum. For adult pests, spray with 80% dichlorvos emulsifiable concentrate at 2000 times dilution; for larvae control, drench the roots with 90% trichlorfon crystal at 2000 times dilution. During the seedling stage, it is also easily damaged by aphids, and spraying with 40% omethoate at 2000 times dilution can be used.
(6) Timely Harvesting
Harvesting by digging can be done in late October. When digging, remove the vine base and wipe the fibrous roots and soil clean, taking care to store thick and thin roots separately. Polygonum multiflorum is a perennial plant, and its root tubers can overwinter underground without affecting growth the following year, while root tuber yield can increase by more than one times.