1. Variety selection In the wild state, plants with good plant type, large leaves, characteristics and high content of Artemisia annua L. are selected as provenance tending objects to improve the quality of species. [4]
2. The site selection for the construction of seed source requires the selection of contiguous growth platforms or gentle slopes with convenient transportation. According to the characteristics of Artemisia annua, it is better to choose the one with good water source conditions as the source nursery. Generally, the area of seed source area should be 0.25% of the planned planting area, and multi-point layout can be adopted. [4]
Arrangement of seed source every year from the end of 1 1 to the beginning of1February, the weeds in the seed source are burned, or the weeds are uprooted and dried. Burn the turf ash, and then spread the turf ash evenly in the seed source. Open a trench around the seed source, and open a cross trench in the middle to prevent waterlogging, and build a fence around the ground with bamboo or branches to enclose the seed source to avoid being trampled by cattle, sheep and livestock. [4]
3. Seed source management at seedling stage The seeds of Artemisia annua L. are unevenly distributed in the wild state. After the temperature rises in warm spring, there are many seeds and the seedlings are thin. Therefore, in the first and middle of April, when the seedling height is 5- 10cm, the seedlings are interplanted and replanted, and one plant is left or replanted every 40-50cm. [4]
Artemisia annua L. likes to fertilize and cultivate soil, and topdressing should be applied after seedling survival (7d). Generally, 60kg of urea, 37.5 kg of calcium superphosphate and 75kg of potassium sulfate should be applied per hm2. One month after seedling replanting, 600-750 kg of compound fertilizer with N, P and K contents of 15% should be applied per hm: combined with weeding. After fertilization, it should be applied. [4]
Topping when the height of Artemisia annua seedlings is 30-50cm, the main buds are removed (called "topping") to promote the germination of lateral branches and improve the seed yield [4].
Pests and Diseases and Their Prevention 3.4. 1 Powdery Mildew Powdery Mildew is the main disease of wild Artemisia annua, which mostly occurs from late April to early May. Prevention and treatment: at the initial stage of the disease, spray 75% chlorothalonil wettable powder 500 times +8% Fenfen microemulsion 1000 times, once every 7 days, and spray for 2-3 times. [4]
Aphids and weevils: control with 12% Lulutong EC 1000 times +70% Aimeile emulsion 1000 times. [4]
4. The core of seed impurity removal and inferior seed quality is the high purity and high quality of varieties. In the process of tending, we must strictly check and do a good job of impurity removal and purity protection in each period. Impurity removal at seedling stage is carried out during thinning, recognizing seedling phase, leaf color and other forms, and pulling out different plants; The second time is carried out during fertilization and soil cultivation; The third time was carried out in early August, and the whole field was dragnet 1-2 times to ensure that the miscellaneous plants were completely removed before harvest. [4]
5. The selection of excellent varieties adopts the method of single plant selection for breeding. In the first ten days of August, the mutant plants with large leaves, good plant type or resistance are selected from the relatively excellent population, labeled, recorded and harvested, and the rest will be reserved for field production in the coming year. The time for single plant selection should not exceed mid-August at the latest, because wild Artemisia annua buds in early September. After Artemisia annua enters the reproductive growth period, the leaves gradually become smaller, so it is difficult to choose a single plant with big leaves. 6 Early or late harvest, drying and storage will affect the yield and quality of seeds. The best harvest time of Artemisia annua seeds is1mid-October, and can't exceed1late October at the latest. When harvesting, cut down all the Artemisia annua without labels, move it to threshing ground, which is sheltered from the wind and sunny, spread it out and dry it 1-2d, then knock off the seeds and dry them, and keep them in a dark and dry place.