The Latest Tutorial on Rehmannia Culture and Propagation Techniques

Rehmannia (Rehmannia glutinosa) is a perennial herb of the genus Rehmannia in the family Scrophulariaceae, and is one of China's traditional precious medicinal herbs. Because it contains rehmannin, cardiac glycosides, various organic acids and vitamins, sugars and other substances, it has the effects of strengthening the heart, promoting diuresis, lowering blood sugar and protecting the liver. Among these, the rhizome of Rehmannia, processed by different methods, can yield Shengdi (raw Rehmannia) and Shudi (prepared Rehmannia), which belong to the class of drugs that clear heat and cool the blood. Shengdi has the effects of nourishing yin and clearing heat, cooling the blood and stopping bleeding, and is mainly used to treat restlessness in febrile diseases, low fever due to yin deficiency, hematemesis, hematuria, metrorrhagia and metrostaxis, and other conditions; Shudi can nourish yin and supplement blood, and is mainly used to treat yin deficiency with scant blood, blurred vision and tinnitus, soreness and weakness of the waist and knees, spermatorrhea, amenorrhea, and other conditions. Refreshing and nourishing beverages containing Rehmannia, such as beer, Rehmannia essence, Rehmannia tea, canned Rehmannia, and Shixiang Rehmannia dishes pickled with fresh Rehmannia, are all very popular on the market.

At present, Rehmannia is propagated by long-term vegetative propagation using rhizomes, so problems such as high material consumption, viral infection and cultivar degeneration exist in the planting process, thereby causing severe damage to Rehmannia resources and resulting in a relatively large gap in the production and supply of high-quality Rehmannia medicinal material.

Collection and treatment of explants

In autumn (September to October), dig up healthy, pest- and disease-free rhizomes of Rehmannia with an underground diameter of about 1.0 cm, rinse them clean with dishwashing liquid and tap water, and cut them into root segments 1.0 to 1.5 cm long. On an ultra-clean workbench, rinse with 75% alcohol for 30 s, disinfect with 0.1% mercuric chloride for 7 to 8 min, and rinse with sterile water 5 to 6 times.

Inducing explant growth and differentiation

Using sterilized scissors or a scalpel, remove from the disinfected explants the cut surfaces that came into contact with the disinfectant solution, exposing fresh tissue. Inoculate the root segments promptly onto culture medium MS with 6-BA 0.05 to 2.0 mg/L and NAA 0.01 to 0.5 mg/L. Be careful not to place the lower end facing upward. Culture the inoculated material at a temperature of about 24°C, with 12 h/d of light and a light intensity of 1,500 lx. One week after inoculation, yellow-green bud points begin to appear on the roots; after about 15 d, adventitious buds grow out; after 30 to 40 d, the buds grow to 2.0 to 3.0 cm.

Subculture proliferation

Remove the above-mentioned shoots and inoculate them onto culture medium MS with 6-BA 1.5 mg/L and NAA 0.1 mg/L. After 10 d, bud clusters (3 to 5) form at the base of the shoots; after 20 to 30 d, the new shoots grow to about 1.0 to 2.0 cm. Subculture about once every 30 d, controlling the proliferation coefficient at about 3 times, so as to obtain sturdy seedlings while maintaining good shoot proliferation.

Rooting and transplanting

Divide rootless seedlings about 3.0 cm tall and growing vigorously into individual plants and inoculate them onto culture medium 1/2 MS with NAA 0.05 mg/L. Generally, after 15 d, a large number of roots can be produced. When the roots are about 1.0 cm long, they can be acclimatized and transplanted. The method is to first place the test-tube plantlets in a glass greenhouse at a temperature of 25°C and a humidity of 75%, uncover the lids and harden the seedlings for 3 d, then gently take the plantlets out of the bottles with tweezers, wash off the residual agar culture medium with a 0.125% to 0.142% dilution of Baijunqing medicinal solution, and then transplant them into a disinfected substrate (perlite: vermiculite = 1:1). After transplanting, maintain a temperature of 24 to 25°C and a humidity above 80%; the survival rate can reach more than 90%.