Detailed Explanation of Key Technical Points for Asarum Seedling Cultivation
AsarumIt can be propagated by seed and by rhizome, with seed propagation being predominant in production. Seed propagation is further divided into direct seeding and seedling transplanting, with the transplanting method commonly used in production. The emergence rate and seedling survival rate of Asarum seedlings, as well as the quality of the seedlings, directly affect the growth and development of Asarum plants after transplanting.
Seed Selection
Asarum seeds mature in mid to late June. After picking, pile them for 2-3 days until the fruits split open and the flesh becomes powdery, then rub them on a sieve. Wash the seeds and flesh that fall through the sieve with water. Remove and discard the shriveled seeds floating on the water surface. Scoop out the semi-mature seeds suspended in the water and sow them separately. Use the plump seeds that sink to the bottom for seedling cultivation.
Seed Disinfection
Asarum seeds often carry various pathogens. To avoid or reduce the pathogens carried by seeds, seeds need to be disinfected before sowing. Soak the seeds in a 1000-fold dilution of 50% carbendazim wettable powder or a 1000-fold dilution of 50% procymidone wettable powder for 30 minutes, then remove and briefly air-dry before sowing.
Timely Sowing
Asarum seeds have physiological after-ripening characteristics and cannot be stored at dry room temperature. Therefore, after the seeds mature and are harvested and cleaned in mid to late June, they should be sown immediately. For seeds that cannot be sown in time for some reason, sand storage treatment is required. Sand-stored seeds can be sown at any time, but no later than early August. Sowing too late can easily break the radicle, and seeds with broken radicles will not emerge after sowing.
Soil Covering Thickness
Asarum seeds are small and the germ has weak ability to push through soil. Covering with too much soil during sowing will affect emergence, reduce the emergence rate, and prolong the emergence period. If the soil cover is too thin, the surface soil may dry out and cause bud damage. Therefore, the soil covering thickness should be properly controlled during sowing, generally 1 cm is appropriate.
Bed Surface Mulching
The growth and development of Asarum seed embryos requires completion under conditions of around 20°C and soil moisture of 30%-35%. To maintain suitable soil moisture, the bed surface should be mulched after sowing. The best mulching materials are larch leaves or rice straw; mountain grass can also be used. The mulching thickness should be 3-5 cm, and it should be removed at emergence.
Pest Control
The main pest during Asarum seedling cultivation is the mole cricket. Mole crickets have phototactic, chemotactic, hygrotactic, and coprophilic characteristics. After careful sowing, the bed surface mulching keeps the soil moist, and moist soil easily attracts mole crickets. Once mole crickets enter the seedbed, they burrow and feed in the surface soil, not only breaking the radicles of Asarum seeds but also causing the soil to become loose and aerated, leading to drying of the seed buds. Control methods: (1) Poisoned manure bait: Mole crickets are coprophilic, so manure with high fiber content such as horse manure or deer manure can be selected. Mix 0.5 g of 80% trichlorfon wettable powder per 30-40 kg of manure, place in small piles on the working paths of the seedling area, and cover with grass. The trapping effect is quite obvious. (2) Chemical control: After sowing, spray the bed surface with a 1000-fold dilution of 50% phoxim, until the bed surface is moist, then immediately cover the bed surface to fumigate and kill the pests. The effect is good.
Light Regulation
One to two-year-old Asarum seedlings have weak light resistance, so a shade shed should be set up immediately after emergence. In the early growth stage, a canopy density of 0.6 and a light transmittance of 40% are appropriate. For seedling cultivation in farmland, from early July to mid-August, mountain grass or leafy branches can be hung on the shade shed to reduce the canopy density to 0.7 and the light transmittance to 30%. Remove the hanging materials in late August. This light regulation method can prevent sunscald caused by excessive light and is beneficial to plant growth and development.
Frost Damage Prevention
Asarum is an early spring plant. Older plants can tolerate low temperatures around 0°C for a short time. One-year-old seedlings only grow 2 tender cotyledons and are not frost-tolerant. Temperatures below 0°C can cause frost damage, causing the affected leaves to dehydrate, wilt, and die, and the underground seed roots will no longer produce renewal buds. Preventive measures include promptly setting up a shade shed after emergence, checking the weather forecast every day, and covering the seedlings with plastic when frosty weather is forecast, which can reduce or alleviate frost damage.
Phytotoxicity Prevention
When using farmland for seedling cultivation with corn planted in surrounding plots, herbicides are sprayed after corn sowing for closed weed control. The spray liquid may drift onto Asarum stems and leaves with the wind, or the plants may be affected by the odor of the spray, causing phytotoxicity to Asarum stems and leaves, and in severe cases, it can destroy the entire field. Preventive measures: negotiate with neighboring farmers who plant corn to determine the spraying time. Before spraying, cover the Asarum seedlings tightly with plastic film, and remove it after spraying to prevent chemical damage.