Rheum tanguticum, also known as rheum henryi.
Tall perennial herb, about 2 meters high, similar to the previous species. Stems glabrous or hairy. Rooted leaves are slightly round or broadly heart-shaped, with a diameter of 40 ~ 70 cm, 3 ~ 7 palmately parted, long and narrow lobes, often pinnately shallow, with sharp apex and heart-shaped base; Cauline leaves are smaller and stalks are shorter. Panicles are large, mostly dark purple when they are young, but also green and white, with tight branches and straight branchlets; Flowers small, with long pedicels; Perianth 6, 2 rounds; Stamens are generally 9; Ovary triangular, style 3. Achenes are triangular, winged, rounded or slightly concave at the top and heart-shaped at the base. The flowering period is from June to July. The fruiting period is from July to September.
Born in a damp place on the edge of mountain forest. Distributed in Qinghai, Gansu and Sichuan. Tibet and other places.
Medicinal rhubarb, also known as Nandahuang.
Tall perennial herb, about1.5m high. Stems erect, sparsely pubescent, with dense nodes. Rooted leaves have long stalks, round to ovoid leaves, 40-70cm in diameter, palmately lobed, or only notched and coarsely serrated, with sharp apex, heart-shaped base, usually 5 main veins, basal, hairless above, or sparse and small papillae near the state vein, with hairs below, which are mostly distributed in the vein and leaf margin; Cauline leaves are small and stalks are short; Leaf sheaths are simple, sparsely short-haired, and split to the base. Panicle, large, branched, small flowers, 3 ~ 4 mm in diameter, 4 ~10 in clusters; Perianth 6, pale green or yellow-white, 2-whorled, the inner whorl is oblong, about 2 mm long, the apex is round, the edge is not neat, and the outer whorl is slightly short; Stamens 9, not exserted; Ovary triangular, flowers on 3. Achene is triangular, winged, about 8 ~10 mm long and 6 ~ 9 mm wide, with concave top and red color. The flowering and fruiting period is from June to July. Most of them grow in mountainous areas with good drainage. Distributed in Hubei, Sichuan, Yunnan, Guizhou and other places.
The stems or young seedlings of the above plants are collectively called rhubarb stems, which are also used for medicine.
morphological character
Rhubarb is a perennial herb of Polygonaceae. Its roots are fleshy, lignified, non-forked, radish-shaped, and some have several forks, which are bull's head-shaped. The stems are erect, unbranched, 90-120cm high, hollow, with longitudinal grooves and pubescence. Rooted leaves are large, nearly round and palmately parted. Inflorescence conical, closely branched, branchlets straight upward, several clustered at each node. Flowers are small, clustered, green and white or deep purple. Achene is red, triangular, oblong, with 3 ribs, rounded or slightly concave at the top and heart-shaped at the base.
Growth habit
Sexual preference for cold climate, cold tolerance and avoidance of high temperature. Wild in the high mountainous areas with an altitude of about 2000 meters in the northwest and southwest of China; The family is planted in the area above 1400 meters. Climatic conditions: the lowest temperature in winter should be above-10℃, the temperature in summer should not exceed 30℃, the frost-free period is 50- 180 days, and the annual rainfall is 55- 1000 mm. The requirements for soil are strict, and it is generally best to use soil with deep soil layer, rich humus and good drainage or sandy soil. Planting in sticky and acidic soil will cause poor growth of rhizomes and affect yield. Plots with poor drainage and high groundwater level are not suitable for planting. Continuous cropping of rhubarb should be avoided, and it should be replanted after 4-5 years. It should be rotated with leguminous and gramineous crops, or codonopsis pilosula and coptis chinensis should be used as the previous crops.
Rhubarb seeds are easy to germinate. At the temperature of 15-25℃, the germination rate can reach more than 85%, and the seed life is l-2 years.
Planting techniques of rhubarb
1.Land selection and preparation
Rhubarb is a deep-rooted plant, the taproot can penetrate into the soil layer for 30-45 cm, and it is better to choose loose and well-drained sandy sloping land. After the previous crops such as corn and potato are harvested, combine deep ploughing and apply sufficient base fertilizer, and apply 4,000-5,000 kg of manure per mu. In poor soil, the amount of fertilizer can be increased.
2. Breeding method
It is mainly propagated by seeds, and can also be propagated by buds. Seed propagation is divided into direct seeding and seedling transplanting.
(1) The live broadcast is conducted in early autumn or early spring. For direct seeding, the distance between rows and plants is 70 cm by 60 cm, and the depth of the hole is about 3 cm. Each hole is sown with 5-6 seeds and covered with soil about 2 cm. The amount of seeds used per mu is 2-2.5 kg.
(2) Seeding and transplanting In order to save seeds and improve land utilization rate, or in areas where direct seeding is not suitable for spring drought, seeding and transplanting are often used. The method is to make a high ridge with a width of1.2 m and a length of 2 1 m on the whole land, and open drainage ditches on all sides. Cross-furrow and drill in the border with a row spacing of12cm and a depth of 5cm, evenly spread the seeds into the furrow, cover it with soil for 2-3cm, and then cover it with a layer of grass. Uncover the grass after germination and excavation. Pay attention to pulling weeds, and apply some dilute human excrement and urine topdressing in May and June. In winter1late October, cultivate the rhubarb seedlings for 3-5 cm to prevent the seedlings from being damaged, and transplant them in the next year.
Transplanting in mid-April (Grain Rain) or late August (summer) in the second year of seedling raising. After digging out the seedlings, cut off the lateral roots of the seedlings, plant them in time on the whole land, with the row spacing of 60 cm each, digging holes 15-30 cm deep, covering each hole 1 plant, burying the reed head, and compacting the soil to make the roots and soil closely combined.
When transplanting, "curved root planting" can be adopted, that is, when planting, the root tip of the seedling is bent upward into an L shape, which can greatly reduce the bolting rate of the plant.
(3) Propagation of sub-buds When harvesting rhubarb, the robust and large sub-buds sprouted from the roots of the mother plant are picked and planted. Too small buds can be planted in seedbeds and then planted in the following autumn. To prevent the wound from rotting, plant ash can be applied to the wound when planting.
3. Field management
(1) In the first year of intertillage weeding, rhubarb seedlings are small, and weeds are easy to grow. Weeds should be weeded frequently in combination with loosening soil, and soybeans and corn should be planted between rows to inhibit the growth of weeds. In the second to third years, weed and loosen the soil in early May and mid-July, and cultivate more soil at the roots.
(2) Fertilized rhubarb is a fertilizer-loving plant, and it needs topdressing 2-3 times a year in addition to basal fertilizer. In June of the first year, 50 kilograms of cake dressing fertilizer and 0-20 kilograms of calcium superphosphate/kloc-0. In the second year, topdressing was conducted twice. In May and June, human excrement or 20-30 kg of calcium superphosphate and 0/0-20 kg of potassium chloride/kloc were applied in furrows between rows respectively, and then covered with soil and watered.
(3) After planting Rheum officinale, bolting and flowering will begin in the second year. Except for planting, the bolting of other plants should be taken off, and bolting should be carried out in sunny days.
4. Pest control
The main disease is root rot, which often occurs in rainy season from August to September, or when it is hot and humid, and often occurs in the year of rhubarb harvest or the year before. The top of the root began to turn black and rot, and the leaves turned yellow at the same time, even dying. The prevention method is to pay attention to the elimination of stagnant water and loosen the soil in time. After dressing, soil the dressing wound or disinfect it with quicklime water. Pull out the diseased plants as early as possible after the onset of the disease, collect dead branches and leaves in autumn and burn them to reduce the source of germs. Insect pests are aphids, which are serious in June and July, and dimethoate emulsion can be sprayed 2000 times. Rodents can be trapped or culled manually.
5. Harvest and processing
After planting rhubarb for 2-3 years, it will be harvested when the aboveground parts wither in September-1October. When harvesting, first cut off the aboveground parts, dig out all the roots and rhizomes, and carefully shake off the soil. The oversized roots can be cut into several pieces, and the medium and small ones can be cut into pieces, dried or dried. After drying, put it in a wooden box or a drug collision device for collision, and knock off the rough skin to show yellow. About 400 kilograms of dry goods can be collected per mu.