Cultivation techniques of rhubarb

Rhubarb, also known as Shengjun, General, Sichuan Army. The taste is bitter and cold. It has the effect of purging excess heat, accumulating stagnation, removing blood stasis and detoxification. For hot constipation, stagnation of abdominal pain, damp-heat jaundice, acute appendicitis, incomplete intestinal obstruction and other diseases. Mainly produces Qinghai, Gansu, Sichuan, Shaanxi and other provinces.

Morphological characteristics

Rhubarb is a perennial herb of Polygonaceae, with fleshy, lignified, unbifurcated and radish-shaped roots, some with several bifurcations and a bull's head shape. Stem erect, unbranched, 90-120 cm tall, hollow, longitudinally furrowed and pubescent. Root leaves large, suborbicular, palmately parted. Inflorescences paniculate, closely branched, branchlets straight upward, several clustered at nodes. Flowers small, several clustered, green-white or thick purple. Achenes red, triangular, oblong, 3-winged, apically rounded or retuse, base cordate.

I. growth habits

Sex like cold climate, cold-resistant, avoid high temperature. Wild in the northwest and southwest of China, about 2000 meters above sea level; domestically planted in areas more than 1400 meters above sea level. Climatic conditions: the minimum 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. There are strict requirements for soil, and it is generally best on soil with deep soil layer, rich in humus and good drainage or sandy soil. Planting in viscous and acidic soil results in poor rhizome growth and affects yield. Plots with poor drainage and high groundwater level should not be planted. Rhubarb taboo continuous cropping, need to be replanted after 5 years, should be rotated with leguminous and gramineous crops, or with Codonopsis pilosula and Coptis chinensis as the previous crop.

Rhubarb seeds are easy to germinate. under the temperature of 15-25 ℃, the germination rate is more than 85%, and the seed life is 1-2 years.

II. Land selection and land preparation

Rhubarb is a deep-rooted plant, the main root can be deep into the soil layer of 30-45 cm, the selection of loose, well-drained sandy soil slope is better, the previous crop corn, potatoes and other harvests, combined with deep ploughing sufficient base fertilizer, 4000-5000 kg per mu of barren soil, but also can increase the amount of fertilizer.

Third, sowing seeds

Rhubarb is propagated mainly by seeds and buds. Seed propagation is divided into two methods: direct seeding and seedling transplanting.

1. Live broadcast: in early autumn or early spring. Direct seeding according to the row distance of 70 cm X 60 cm hole sowing, hole depth of about 3 cm, each hole sowing 5-6 seeds, covering soil about 2 cm. The amount of seed used per mu is 2-2.5 kg.

2. Seedling transplanting: in order to save seeds and improve land utilization, or in areas where direct seeding is not suitable for direct seeding in spring, sowing and transplanting are often used in the field. The method is to make a high border with a width of 1.2 meters and a length of 21 meters, and open drainage ditches on four sides. Sow horizontally in trenches on the border, with a row spacing of 12 cm and a depth of 5 cm. Spread the seeds evenly into the ditch, cover 2-3 cm of soil, and then cover with a layer of grass. Uncover the grass after sprouting. Pay attention to pulling grass and apply some rare manure manure from May to June. Cultivate 3-5 cm soil on the rhubarb seedling line in late October to prevent damage to the seedlings, and transplant the following year.

Seedlings were transplanted in mid-April (Grain Rain) or late August (the End of Heat) in the second year. After digging out the seedlings, cut off the lateral roots of the seedlings and plant them in time on the whole land, with a row spacing of 60 cm and a hole depth of 15-30 cm, with 1 plant per hole, covering the soil, burying the Reed head, compacting the soil and closely combining the root with the soil.

When transplanting, "curved root colonization" can be adopted, that is, the root tip of the seedling will be bent upward in L shape during transplanting, which can greatly reduce the bolting rate of the plant.

3. Seed bud propagation: when harvesting rhubarb, the strong and large seed buds sprouting from the rhizome of the mother plant were picked and planted. Buds that are too small can be planted in a seedbed and replanted the following autumn. To prevent the wound from rotting, plant ash can be applied to the wound when planting.

IV. Field management

1. Weeding in middle ploughing: rhubarb's first young seedlings are small and weeds are easy to grow. Combined with loosening the soil, weeds should be weeded frequently, and soybean 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. Fertilization: rhubarb is a fertilizer-loving plant, which needs topdressing 2-3 times a year in addition to base fertilizer. In June of the first year, 50 kg per mu of topdressing fertilizer and 10-20 kg of calcium superphosphate. Topdressing twice in the second year, ditching human feces and urine in May and June, or 20-30 kg of calcium superphosphate and 10-20 kg of potassium chloride, covering soil and watering.

3. Bolting: after planting, rhubarb begins to bolt and blossom in the second year. Except for the seed land, the bolting of other plants should be carried out on a sunny day.

Prevention and control of diseases and insect pests

The disease is mainly root rot, which occurs in the 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 begins to blacken and rot, and the leaves turn yellow at the same time, so that they die. The method of prevention and control is to eliminate stagnant water and loosen the soil in time. After bolting, treat the bolting wound with soil, or disinfect it with raw lime water. After the onset of the disease, the diseased plants were removed as early as possible, and the dead branches and leaves were collected and burned in autumn to reduce the source of bacteria.

Insect pests are aphids, which are serious from June to July, and can be sprayed with dimethoate emulsion 2000 times. Rodent damage can be trapped or culled manually.

VI. Harvesting and processing

Rhubarb was planted for 3 years and harvested when the shoot withered from September to October. When harvesting, first cut off the ground part, dig out the rhizome and roots, shake off the soil carefully, the oversized rhizome can be cut into several pieces, medium and small pieces, air-dried, sun-dried or dried. After drying, it will be crashed into a wooden box or collision equipment to remove the rough skin and expose the yellow color. About 400 kilograms of practical information can be collected per mu.

7. Seed retention techniques

Select the three-year-old plants with strong growth, no diseases and insect pests and purer varieties, strengthen the field management, and set up a support during the flowering stem in 5m months to avoid being broken by the wind. Seeds are easily blown off by the wind when they mature, so we should always pay attention to their growth. When some of the seeds are dark brown in the middle and last ten days of July, they will be cut back quickly and placed in a ventilated and humid place to ripen after ripening, and they will be used as seeds after several days of shaking. Seeds for spring sowing should be stored dry in the shade to avoid damp and mildew.