A Complete Analysis of the Key Cultivation Techniques for Pseudostellaria heterophylla
Pseudostellaria heterophylla is the dried tuberous root of the caryophyllaceae plant Pseudostellaria heterophylla (Mig.) Pax ex Pax et Hoffm., also known as tongshen or hai'ershen. It has the functions of tonifying qi and strengthening the spleen, promoting fluid production and moistening the lungs. It is mainly produced in Jiangsu, and is cultivated in Fujian, Anhui, Zhejiang and Shandong.
(1) Morphological Characteristics
Perennial herb, plant height 10-20 cm. Tuberous roots numerous, fleshy, spindle-shaped, outer skin pale yellow, sparsely bearing fibrous roots. Stem erect, nearly square, nodes slightly swollen, internodes with two rows of short soft hairs. Leaves opposite, nearly sessile, lower leaves spatulate or oblanceolate, upper leaves ovate-lanceolate to oblong-ovate, about 7 cm long and about 1 cm wide; at the stem tip there are 4 large leaf-like involucral bracts. Flowers axillary, dimorphic; the cleistogamous flowers near the ground on the lower stem are small, purple, with 4 sepals, closed, without petals, stamens usually 2. At the top of the stem 1-3 ordinary flowers are borne, larger in size; white, with 5 sepals, 5 petals, obovate, 10 stamens, 3 styles, ovary superior. Capsule nearly spherical, drooping when ripe, dehiscing. Seeds 7-8, flat spherical, purplish brown, surface with warty dots. Flowering period April-May, fruiting period May-June.
(2) Growth Habits
Pseudostellaria heterophylla is mostly found wild in the rock crevices and litter layers of shady, moist hillsides. It prefers loose, humus-rich, well-drained sandy loam soil. It is suited to a mild and humid climate, growing vigorously at an average ten-day temperature of 10-20°C, and it is intolerant of high temperatures and strong light exposure in midsummer; when the temperature reaches above 30°C, plant growth stagnates. In late June the plants begin to wither and enter summer dormancy. Pseudostellaria heterophylla is highly cold-resistant and can overwinter safely at -17°C. It likes fertilizer and fears waterlogging; after water accumulation the roots easily rot. Seeds should not be dried and stored for long; they are best sown as soon as collected, and they must meet a certain low-temperature condition to germinate. Therefore, under natural conditions, seedlings from seed can only be seen in spring, while the vegetative seedlings grown from seed tubers have already emerged in spring. After emergence, the plants gradually grow faster, the above-ground parts form branches, and the leaves enlarge. The underground stem has the characteristic of "rooting at the nodes", and as the above-ground parts grow, it expands into spindle-shaped tuberous roots. From spring emergence to summer withering, the whole growth period of Pseudostellaria heterophylla is about 4 months.
(3) Cultivation Techniques
1. Land selection and preparation: Choose fertile, loose, well-drained sandy loam soil rich in humus. Avoid continuous cropping; the previous crop is best as sweet potato, vegetables, etc., and for sloping land, north- and east-facing slopes are preferable. Generally, after the early-autumn crops are harvested, plow the land and apply a heavy base fertilizer, mainly farmyard manure, which should be thoroughly decomposed. Rake fine and harrow evenly, and make beds 1.2-1.5 m wide and 20 cm high, keeping the bed surface arched.
2. Propagation methods: These can be divided into sexual propagation and asexual propagation. However, because sexual propagation is difficult for seed collection and the yield in the same year is low, asexual propagation is mainly used in production. The sowing time is best before late October; if too late, the seed tubers begin to sprout due to falling temperatures, and the buds are easily damaged during planting, affecting emergence the following year. Seed tubers should be selected as tuberous roots with intact buds, plump bodies, no injuries and no pests or diseases. When planting, first open transverse furrows about 13 cm deep on the prepared bed surface, then plant the seed tubers diagonally in the furrows at a plant spacing of 5-7 cm, with the buds facing upward and 6 cm from the bed surface, and with the bud positions at the same level, commonly called "even at the top, uneven at the bottom". Then open a second furrow at a row spacing (furrow spacing) of 15 cm, and cover the first furrow already arranged with tubers using the soil from the latter furrow, then arrange the tubers again, and so on. After planting one bed, press lightly and shape the bed surface into an arch. The seed quantity used is 40-60 kg per mu.
3. Field management
(1) Prevent trampling by people and livestock: In the year after planting, the seedlings do not emerge, so the bed surface should be kept level and trampling by people and livestock should be avoided; otherwise it easily causes local short-term water accumulation, making the roots rot and ultimately leading to missing plants and reduced yield. In seed-production fields, trampling should be prevented even more during the summer.
(2) Weeding and earthing up: In early February, when the seedlings emerge, growth is slow and overwintering weeds proliferate, so a shallow hoeing can be done once with a small hoe, and thereafter weeds should be pulled as soon as they appear. At the same time, in combination with tidying the bed furrows, move the soil that has collapsed from the bed edges back onto the bed surface, or use outside soil to earth up; the thickness of earthing up should preferably not exceed 2 cm. After early May, the plants have long since closed the rows, and except for pulling large weeds, weeding can be stopped.
(3) Topdressing: Pseudostellaria heterophylla has a short growth period and mainly relies on base fertilizer; especially in the later stage, improper topdressing, such as applying too much nitrogen fertilizer, can cause excessive stem and leaf growth and affect yield. If the seedlings are thin and weak, 30-40 kg of decomposed cake fertilizer can be applied per mu in early April, followed by watering.
(4) Drainage and irrigation: Pseudostellaria heterophylla fears waterlogging, so after rain the bed furrows must drain smoothly. During dry weather with little rain, attention should be paid to watering to keep the bed surface moist, which is beneficial for root development and plant growth.
4. Pest and disease control
(1) Viral disease: Affected plants have shrunken leaves and mosaic symptoms, the plants wither early, and the tuberous roots are thin and small. Integrated control should be adopted: pay attention to controlling aphids; select disease-free plants or seedlings from seed for seed production; practice crop rotation.
(2) Leaf spot disease: It occurs mostly in the rainy seasons of spring and summer, damaging leaves, and in severe cases the plants wither and die. Generally, in the early stage of the disease, spray with 1:1:100 Bordeaux mixture once every 7-10 days, or spray with 65% zineb wettable powder at 500-600 times dilution for control.
(3) Cutworms, white grubs and wireworms: The larvae bite and feed on the tuberous roots or rhizomes, and the damage is especially serious when the tuberous roots are expanding and the above-ground parts are about to wither. Poison bait made with trichlorfon can be prepared and scattered in the field in the evening to trap and kill them.
(4) Harvesting and processing
In late June, when the plants wither and fall, except for seed-production plots, digging should begin. For harvesting, choose a sunny day, wash off the soil, blanch in boiling water for 2-3 minutes, take out and sun-dry until half dry, rub off the fibrous roots, pile them up to let them regain moisture, and then sun-dry until completely dry. The product obtained by this method is commonly called blanched shen, or it may be directly sun-dried without blanching after digging, which is called raw sun-dried shen. The best product is dry, free of fibrous roots, uniform in size and slightly yellow in color.
(5) Seed tuber preservation techniques
When digging the tubers, select tuberous roots that are plump, have full buds and are free of pests and diseases as seed tubers, and store them in sand in a cool indoor place, keeping them moist regularly, turning them once every 15-20 days, protecting them from rain, and avoiding sand storage on cement floors. Take them out at planting time and select again. The in-situ seed preservation method can also be used, that is, when digging the tubers, leave part of the tuber beds undug, and in early May interplant soybean or sweet potato in the tuber field. When the plants wither and fall, cover the bed surface with soil from the bed furrows to a depth of 3-5 cm; by then the leaves of soybean or sweet potato have covered the bed surface, which both shades and maintains a certain amount of moisture, benefiting the seed tubers through the summer. Pseudostellaria heterophylla seeds have strong germination ability, but the fruits easily split after ripening, the seeds easily scatter, and propagation by seed grows slowly. Producing areas can use naturally scattered seeds for in-situ seedling raising. The method is: after the tuberous roots are harvested, immediately fertilize, plow, prepare the land and make beds, and plant radish, green vegetables and other vegetables. After the seeds germinate and emerge in early spring of the following year, remove or harvest the above-ground crops, and carry out thinning and weeding management. In early May, interplant soybean, etc., to protect the seedlings through the summer. When planting in autumn, they can be harvested for use as seed tubers. When seed tubers are scarce, this method can often be used to propagate seed tubers.