Key Management Techniques for Saposhnikovia divaricata During the Seedling Stage
The main direction of management during the seedling stage of Saposhnikovia divaricata is to promote strong seedlings and early growth on the basis of ensuring a full stand.
(1) Control the temperature of the arched shed: When raising seedlings in a plastic film arched shed, the period from sowing to emergence is a sealed period. Frequent checks should be made to control the temperature inside the shed well, generally with 20°C-25°C as the suitable temperature. If the weather is too hot and the temperature inside the shed is too high, straw mats should be added for shading to lower the temperature. When the medicinal seedlings on the seedbed surface begin to show green, the temperature inside the shed can be adjusted by uncovering the film for ventilation. As the seedlings grow, gradually enlarge the ventilation openings for hardening the seedlings until the plastic film is removed. If weeds appear in the seedbed, they should be pulled out promptly.
(2) Drought resistance and moisture conservation: In open-field seedling fields and directly sown production fields, before and after emergence, due to climatic influences and poor management, missing seedlings and broken rows are prone to occur. Therefore, measures to preserve seedlings should be taken. If the seeds have not yet taken root and the covering soil layer is severely losing moisture, with the danger of drying down to the seed layer, timely compaction should be carried out, using measures such as pressing, treading, rolling, and compacting with a roller according to local and timely conditions, to increase surface soil moisture and ensure sufficient soil moisture within the sowing layer to meet the needs of germination. If irrigated land suffers from drought, sprinkling water or light flooding irrigation can be adopted to keep the soil moist and promote seed germination and emergence. If rain compacts the soil, shallow cultivation and loosening of the soil should be carried out promptly after each rain to break the crust, help seedlings emerge, and prevent wind penetration and moisture loss that may cause soil "drying out" and seeds "drying of sprouts". After emergence, check row by row. If missing seedlings and broken rows are found, promptly carry out germination-accelerated reseeding, or combine thinning with transplanting to fill gaps, striving to achieve a full and uniform stand.
(3) Thinning and final singling: Production practice has found that early thinning and final singling can avoid crowding of young seedlings, reduce consumption of fertilizer and water, maintain a certain nutritional area for each individual plant, and promote strong seedlings and early growth. If thinning and final singling are done too late, the young seedlings compete with each other for fertilizer, water, and light, resulting in weak, leggy, and late-developing seedlings. Therefore, thinning and final singling should be carried out promptly. Generally, 15-20 days after emergence, when the seedlings are about 5 cm tall, thin the seedlings at a plant spacing of 7 cm to prevent excessive crowding and weak, spindly growth. When thinning, be careful not to damage neighboring young seedlings, and select and retain 2-3 robustly growing young seedlings. When the Saposhnikovia divaricata seedlings have grown for about one month and reached a height of more than 10 cm, carry out final singling. In seedling fields, the seedling spacing is 2-3 cm, and in production fields, the seedling spacing is 13-16 cm.
(4) Intertillage and weed control: The seedbed surfaces of directly sown Saposhnikovia divaricata fields and open-field seedling beds often grow many weeds, affecting seedling growth. Early intertillage can loosen the soil, reduce water evaporation, raise soil temperature, eliminate weeds, prevent weed infestation from suppressing seedlings, and create a good environment for seedling root growth. Generally, 2-3 intertillage and weed control operations are required before June. When the medicinal seedlings are emerging, hoe shallowly once to help the seedlings emerge. After a full stand, a general deep hoeing can be carried out to promote deeper root growth. After final singling, hoe deeply once again. If it rains or after watering, timely intertillage should be carried out to break the crust. Make sure to hoe after rain and hoe whenever there are weeds, so as to facilitate early seedling development and achieve the goal of strong seedlings.
(5) Pest control: During the seedling stage, pests such as mole crickets, white grubs, cutworms, wireworms, and weevils occur and cause damage one after another. Disease and pest forecasting should be done well, and timely control should be carried out to ensure a full stand, strong seedlings, and early growth. Control methods: First, adopt agricultural measures such as deep plowing and soil improvement, crop rotation, rational irrigation, and not applying undecomposed organic fertilizer; second, use black light traps and other methods for manual trapping and killing; third, carry out chemical control methods such as soil treatment with chemicals, seed dressing with chemicals, and poison bait.
(6) Transplanting and field planting: Before germination in early spring, transplant the already grown seedlings. In the prepared transplanting field, open furrows transversely at a row spacing of 30 cm for planting, with a furrow depth of 10-15 cm and a plant spacing of 13-16 cm. If the soil is compacted and dry, carry out water-established transplanting, or hole planting can also be used. The hole spacing is 10-20 cm, with 2 plants per hole. The transplanting holes should be slightly larger. When planting, plant upright and firmly so that the root system spreads out. After planting, cover with soil and press firmly. Where conditions permit, it is best to water once uniformly with water for settling roots and reviving seedlings to improve the survival rate of planting.