How to Cultivate Astragalus sinicus for High Yield? A Detailed Guide to Planting Techniques

Astragalus sinicus, also known as qiaoyao, red flower grass, or caozi, originated in China. It prefers warm and humid conditions, has a certain degree of cold tolerance, and requires sufficient water throughout its entire growth period. Astragalus sinicus is not demanding regarding soil, with sandy and clay loam being more suitable. It has poor salt tolerance and belongs to the Fabaceae family, Astragalus genus. It is a biennial herbaceous plant. Astragalus sinicus prefers a warm and humid climate, with an optimal growth temperature of 15-20°C. It is moisture-tolerant; from sowing to germination it must not lack water, and during growth and development it dislikes waterlogging. Its drought tolerance is weak; prolonged drought can cause Astragalus sinicus to flower early and reduce yield. Astragalus sinicus prefers sandy loam or clay loam and also adapts to non-calcareous alluvial soil. Its tolerance to poor soil is weak; it grows poorly in clay soil and low-lying wet fields with poor drainage, or in sandy soil with poor fertilizer and water retention. It is relatively acid-tolerant but weakly alkali-tolerant, with a suitable pH of 5.5-7.5. When soil salt content exceeds 0.2%, it is prone to dying.

Morphological characteristics of Astragalus sinicus: biennial herb, much branched, prostrate, 10-30 cm tall, covered with white appressed soft hairs. Odd-pinnate compound leaves with 7-13 leaflets, 5-15 cm long; petiole shorter than the rachis; stipules free, ovate, 3-6 mm long, apex acute, bases more or less connate with each other, ciliate; leaflets obovate or elliptic, 10-15 mm long, 4-10 mm wide, apex obtuse-rounded or slightly retuse, base broadly cuneate, nearly hairless above, sparsely white-pilose beneath, with short petiolules. Racemes bearing 5-10 flowers, umbel-like; peduncle axillary, longer than the leaves; bracts triangular-ovate, about 0.5 mm long; pedicels short; calyx campanulate, about 4 mm long, covered with white soft hairs, calyx teeth lanceolate, about 1/2 the length of the calyx tube; corolla purplish-red or orange-yellow, standard obovate, 10-11 mm long, apex slightly retuse, base gradually narrowed into a claw, wings shorter than the standard, about 8 mm long, blade oblong, base with a short auricle, claw about 1/2 the length of the blade, keel nearly equal to the standard in length, blade semicircular, claw about equal to 1/3 the length of the blade; ovary hairless or sparsely covered with white short soft hairs, with a short stipe. Legume linear-oblong, slightly curved, 12-20 mm long, about 4 mm wide, with a short beak, black, with raised reticulate veins; seeds kidney-shaped, chestnut-brown, about 3 mm long. Flowering period February-June, fruiting period March-July.

The main root of Astragalus sinicus is relatively thick and fleshy, generally penetrating 40-50 cm into the soil. Lateral roots penetrate relatively shallowly, so its drought resistance is weak and its moisture tolerance is strong. Root nodules can form on the main root, lateral roots, and fine roots on the soil surface of Astragalus sinicus, mostly on the lateral roots. The stem is cylindrical, hollow, tender and juicy, with sparse fine hairs. Cultivated varieties generally have a plant height of 80-120 cm, while wild ones are only 10-30 cm. The leaves are mostly odd-pinnate compound leaves with 7-13 leaflets. Leaflets entire, obovate or elliptic. The inflorescence is an umbel, generally axillary, rarely terminal, often with 8-10 or more florets, clustered on the pedicel and arranged in a whorl. Legumes in two rows, united into a triangle, slightly curved, hairless, with a beak at the apex. Each pod has 4-10 seeds; seeds kidney-shaped, seed coat smooth, generally yellow-green. 1000-seed weight 3-3.5 grams.

How to cultivate Astragalus sinicus for high yield?

1. Dig the "three ditches". Waterlogging damage in rice fields is one of the important obstacles to high yield of Astragalus sinicus. Generally, at the late tillering stage of late rice, combined with field drying, the outline of the "three ditches" is opened, and before sowing, the compartment ditch, surrounding ditch, and main ditch are opened according to standards. Compartment width 2.7-3 m, compartment ditch width 24 cm, ditch depth 30 cm; surrounding ditch and main ditch width 30 cm, and the ditch depth must break through the plow pan. 2. Seed treatment. Before sowing Astragalus sinicus, the seeds should be treated to increase the germination rate, make the seedlings emerge neatly and robustly, and lay the foundation for high yield. (1) Sun-drying seeds: Before sowing, choose a sunny day and sun-dry the seeds for 1-2 days. During drying, spread them evenly and turn them frequently so that the degree of drying is uniform. (2) Seed selection: Use a 10% saltwater solution for seed selection, and remove shriveled seeds, impurities, and pathogens. (3) Seed scarification: Mix 1.5-2 kg of fine sand per 10 kg of seeds, and pass through a rice mill 1-2 times, until the seeds are slightly warm. This can break the waxy layer on the seed coat, which is beneficial for germination after sowing. (4) Seed soaking: Soak the seeds in a 0.2% ammonium molybdate solution for 24 hours, or soak them in a 20% solution of decomposed human urine for 16 hours. This not only allows the seeds to absorb enough water and facilitates germination, but also has a yield-increasing effect. (5) Inoculation with bacteria: Inoculating with rhizobia is an important measure to increase yield in fields newly planted with Astragalus sinicus. Mix 4 grams of bacterial powder with a small amount of water per kilogram of seeds, and after mixing, avoid direct sunlight. (6) Seed dressing: Mix 5 kg of superphosphate per mu with 20-25 kg of soil and miscellaneous fertilizer evenly, compost for 5-6 days, then mix thoroughly with the seeds, and sow immediately after mixing. 3. Sowing. The suitable sowing period is early September to mid-October, and it can be flexibly controlled according to the local climate and the harvest time of the previous crop. The sowing rate per mu is 1.5-2 kg. 4. Field management. Field management of Astragalus sinicus should focus on five key points. (1) Drought resistance and waterlogging prevention to preserve full seedlings: If dry weather occurs after sowing, irrigate once with "horse-racing water" to keep the field moist, which can both meet the water needs of Astragalus sinicus seeds and meet the water and air requirements of late rice in the later stage, conducive to grain filling and seed setting. After the late rice is harvested, promptly clean up the "three ditches" to ensure the "three ditches" are unobstructed and drainage and irrigation are convenient. (2) Topdressing seedling-promoting fertilizer before winter: Generally after emergence, apply 250-300 kg of thin manure water per mu, combined with drought-resistant watering, to make full use of the temperature and light conditions before winter and accelerate seedling growth. (3) Apply winter fertilizer well to prevent freezing damage: In early to mid-December, apply 400-500 kg of soil and miscellaneous fertilizer plus 25-30 kg of superphosphate per mu to enhance cold resistance and reduce freezing damage. Increasing the application of superphosphate is an important yield-increasing measure of using small fertilizer to nourish large fertilizer, and it should not be ignored. (4) Topdressing spring fertilizer to promote spring growth: After the beginning of spring, topdress 2-4 kg of urea per mu, applying according to seedling condition, to promote balanced growth and build a framework for high yield. Foliar spraying with 0.2% borax solution 2 times can increase fresh grass yield by 20%. (5) Prevent and control diseases and pests to ensure high yield: Astragalus sinicus mainly has pests and diseases such as aphids, leafminers, and sclerotinia. Spray pesticides in time for prevention and control. For aphids and leafminers, generally use omethoate or dichlorvos 1000-fold solution for spray control; for sclerotinia, use 150 ml of 40% miewbingwei or 75-100 g of 70% thiophanate-methyl, mixed with 50 kg of water for spraying. 5. Seed production. Choose fields with good drainage, sandy soil, medium fertility, and no continuous cropping as seed production fields. It is best to choose Astragalus sinicus seeds with good variety, high yield, pure seed characteristics, and late maturity for sowing, and the sowing rate per mu can be reduced to about 1.5 kg. Seed production fields should not be applied with nitrogen fertilizer; increasing the application of about 10 kg of superphosphate and 10-15 kg of plant ash per mu can improve seed yield and quality. The maturity period of Astragalus sinicus pods is inconsistent; generally, it is best to harvest when 80% of the seed pods have turned black. Usually, 50-60 kg of seeds can be harvested per mu.