Technical Specification for Rice Seedling-Throwing Cultivation with Plastic Trays and Dry Raising

Variety selection According to different cropping rotations, variety characteristics and the safe full-heading stage, select high-quality, high-yield, stable-yield varieties with strong tillering ability and good stress resistance that are suitable for local planting, either balanced panicle-grain type or large-panicle type. In the riverside and southern Jiangsu areas, early-maturing late japonica rice varieties are mainly used, supplemented with late-maturing medium japonica rice varieties. For early-maturing late japonica rice, the key varieties selected are Nanjing 44, Ningjing 3, Yangjing 4038, Wuyunjing 23, Zhendao 11, etc.; for late-maturing medium japonica rice, the key varieties selected are Wuyunjing 24, Huaidao 13, Huaidao 9, etc. In the central Jiangsu and Lixiahe areas, late-maturing medium japonica rice varieties are mainly used, supplemented with medium-maturing medium japonica rice and early-maturing late japonica rice varieties. For medium-maturing medium japonica rice, the key varieties selected are Lianjing 7, Xudao 3, Wuyunjing 21, etc. In the Huaihe riverside and Huaibei areas, medium-maturing medium japonica rice varieties are mainly used, supplemented with late-maturing medium japonica rice varieties.

Strong seedling standard The seedlings are neat and uniform, seedling age 30-35 days, leaf age 5.5-6.5 leaves, seedling height 13-18 cm, basal stem thickness 0.35-0.45 cm, green leaves per plant 4.5-6, white roots 12-18, tillers 0.5-1, dry weight per 100 plants about 7.5 grams, and free of pests and diseases.

Seedling raising preparation 20 days before sowing, apply 30 kg each of urea and 45% BB fertilizer per mu of seedling field, and plow and turn the soil promptly after fertilization. The seedbed is required to be 140 cm wide, with furrows 25 cm wide and 20 cm deep, with supporting inner and outer furrows to ensure smooth drainage. About 20 days before sowing, on a sunny day, prepare 250-300 kg of nutrient soil per mu of main field for later use, and the nutrient soil must be disinfected. After the seeds are sun-dried and screened, they are disinfected. For every 5 kg of rice seed, use 2 ml of 25% prochloraz emulsifiable concentrate plus 2 ml of 4.2% dithiocyano-methane emulsifiable concentrate, or 15 g of 16% prochloraz-cartap wettable powder, add 9-10 kg of water and soak for 60-72 hours, then sow directly without pregermination; or directly use “Hanyu Baomu” for seed dressing and coating before sowing. Prepare about 55 seedling trays with 434 holes per mu of main field. Prepare sufficient seedbed according to a seedling field to main field ratio of 1:35.

Determining the sowing date Determine the sowing date according to the suitable seedling-throwing age of 30-35 days. In the Huaibei area it is generally May 15-25, in the central Jiangsu area generally May 10-20, and in the southern Jiangsu area generally May 5-15.

Sowing procedure Before laying the trays, water the seedling bed thoroughly. Place the trays in two rows horizontally, with trays closely adjacent leaving no gaps, and the tray bottoms in close contact with the bed surface. Use fertile soil as seedling-raising soil and spread it evenly into the trays. After spreading soil, fix the bed and sow evenly at a fixed rate, with 3-4 seeds per hole. Cover the seeds with nutrient soil that has not been mixed with seedling-strengthening agent until the holes are full. If conditions permit, water thoroughly by sprinkling; if furrow irrigation is used, it must be irrigated and drained quickly. After the water for full seedling emergence has drained, surround the trays with mud, then cover flat with plastic film or non-woven fabric, and then add a cover of wheat straw, etc., maintaining a light transmittance of 10%-15%. During the period of film (non-woven fabric) and straw covering, no irrigation is needed, and standing water in the seedling field should be drained promptly on rainy days.