Research progress on Ezhu cultivation

Abstract:Ezhu is one of the legal sources of the Chinese medicine Ezhu. Ezhu mainly contains volatile oils and curcuminoids, among which the volatile oil is the effective antitumor component of Ezhu, and curcumin is the main effective component of Ezhu for lowering blood lipids, antioxidation and anti-inflammation, giving it high medicinal and economic value. This paper reviews the research progress on the cultivation techniques of Ezhu. There is a general lack of standardized cultivation management in Ezhu growing areas. Therefore, to accurately master the Ezhu cultivation techniques in South China, the author reviews the research progress on Ezhu cultivation in South China from the aspects of seedling raising, field planting and management, fertilizer and water management, and pest and disease control. The development trend of the Ezhu industry is discussed, and it is proposed that pollution-free standardized cultivation and extending the industrial chain are the fundamental ways for the sustainable development of the Ezhu industry, thereby improving the yield and economic benefits of Ezhu.

Keywords:Ezhu; cultivation techniques; research progress

1. Introduction

Yujin is one of the commonly used Chinese medicinal herbs, being the dried tuberous root of the Zingiberaceae plants Curcuma wenyujin Y. H. Chen et C. Ling, Curcuma longa L., Curcuma kwangsiensis S. G. Lee et C. F. Liang, or Curcuma phaeocaulis Val. [1]. Ezhu mainly contains volatile oils and curcuminoids, and also resins, sugars, fatty acids, sterols, polypeptides, alkaloids and trace elements, among which the volatile oil is the effective antitumor component of Ezhu, and curcumin is the main effective component of Ezhu for lowering blood lipids, antioxidation and anti-inflammation [2]. Ezhu is mainly produced in Guangxi, Guizhou and other places [3]. In the domestic market, about 50% of the demand for Ezhu is used to produce Chinese herbal decoction pieces, and nearly 50% is used for Chinese patent medicines, extracts and preparations. In addition to medicinal use, Ezhu can also be used as pigments, dyes and insecticides, and thus has huge development potential in both domestic and international markets [4].

At present, research on Ezhu mostly focuses on medicinal components, pharmacology and clinical application, while there is little on high-yield cultivation techniques for Ezhu. Carrying out research on Ezhu cultivation techniques is of great significance for improving farmers' economic benefits, and can serve as a high-benefit industry to help farmers escape poverty and become prosperous. In order to accurately master the Ezhu cultivation techniques in South China, research progress on Ezhu cultivation techniques is therefore reviewed here, providing a reference for producing high-yield, high-efficiency Ezhu medicinal material.

2. Research on key techniques for Ezhu cultivation

2.1 Variety selection

Select varieties suitable for planting in South China, such as Curcuma kwangsiensis, Curcuma wenyujin and Curcuma phaeocaulis.

2.2 Seed ginger preparation

Before sowing, select two-bud, three-bud and other straight rhizomes with a diameter of 20 mm or more and a length of 50 mm or more, or large daughter ginger with a diameter of 15 mm or more and a length of 70 mm or more as seed ginger; rhizomes that are bruised or moldy cannot be used as seed ginger [5]. Before planting, cut large Ezhu seed pieces lengthwise into two, taking care not to damage the buds, and plant after the cut surface has dried, or dip the cut surface in plant ash and plant immediately [6].

2.3 Land selection and preparation

Select dry land or sloping land with rich organic matter, good fertility, sufficient sunlight, good drainage and loamy soil for planting. Before planting, plow and harrow 1 to 2 more times, to a depth of 20 to 25 cm; deep plowing is not advisable, so that the plow layer is loose and level. After plowing and sunning the soil for about one month or more, apply 50 to 100 kg of phosphate fertilizer per mu, mixed with 1500 to 2000 kg of cow dung, broadcast as base fertilizer, then harrow fine and level, and form beds [7]. Make narrow beds on flat land and wide beds on sloping land, to facilitate drainage and prevent waterlogging while retaining appropriate moisture.

2.4 Sowing

Plant in early April. For Curcuma phaeocaulis, the planting density is 35 cm×30 cm between plants and rows, with 4800-5200 plants per mu. Apply barnyard manure and turf ash mixed fertilizer in the holes, 3000 kg per 667 sq m; after application, cover the fertilizer with a layer of soil, place 1 seed stem per hole, each weighing about 15 g with 1 to 2 strong buds, with the bud eye facing upward when planting, at a depth of about 5 cm, then cover with soil, then cover with a layer of rice straw, and water thoroughly. Use about 125 kg of seed per mu [6].

2.5 Fertilization

At planting, apply 30 to 50 kg of potassium sulfate compound fertilizer per mu as seed fertilizer; take care not to apply it too close to the Ezhu seed, and it may be applied between two plants. In June to July, apply topdressing 1 to 2 times as appropriate according to seedling growth. Each time use 5 kg each of urea and potassium fertilizer (potassium sulfate is best) per mu, broadcast after rain. If conditions permit, liquid topdressing with biogas slurry, human excreta, oil bran fermentation liquid, plant ash, etc. is even better [7]. The absorption ratio of nitrogen, phosphorus and potassium by Ezhu varies with the growth period. Generally speaking, the absorption of nitrogen is the greatest, and the absorption of phosphorus and potassium is similar. The absorption of nitrogen, phosphorus and potassium by the plant is highest at 99 d after emergence, and nitrogen absorption is the greatest; the total absorption ratio of nitrogen, phosphorus and potassium over the whole growth period is 1:0.38:0.37 [8].

2.6 Pest and disease control

The principle of pest and disease control is to give priority to integrated control, giving priority to agricultural control, biological control and physical-mechanical control, with chemical control as the last measure.

Main insect pests: the ginger skipper (commonly known as green maggot) and locusts (soil locusts). If they occur in large numbers during the growing season, thoroughly clean the field after harvest, burn the dead branches and fallen leaves to eliminate overwintering eggs, or spray with 90% crystallized trichlorfon at 800 to 1000 times dilution to kill the larvae in the early stage of occurrence; for ground tigers (commonly known as soil silkworms), white grubs (commonly known as soil turtle maggots), mole crickets and crickets, drench with phoxim or make poisoned soil and apply with the seed for control; or use 15 to 20 kg of tea seed cake per mu, crush into fine powder, add water and soak until rotted for about one week, then add 50 kg of plant ash and apply as base fertilizer before sowing. For root-knot nematode disease, implement crop rotation or apply Paecilomyces lilacinus (Xianchongqing) for control [5,7].

Main diseases: ① Leaf spot, which can be controlled by spraying thiophanate at 500 times dilution. ② Rotting Fuling syndrome. Give priority to agricultural preventive measures: select healthy Ezhu heads as seed and disinfect the seed (soak the seed in 500 times strong bleaching powder for 20 minutes); select new land for planting, do not practice continuous cropping; for root rot, rotate with gramineous crops and rapeseed and other crops, or drench the holes with 5406 bacterial powder or Trichoderma preparation at 1500 to 2000 times dilution [5,7].

2.7 Plastic film mulching

Plastic film mulching cultivation has a good promoting effect on the yield components of Ezhu [9]. Through the film-covering method, Ezhu is cultivated using the "three avoidances" technique (avoiding cold, avoiding rain, avoiding sun), with outstanding results. First, it prevents weed growth; second, it keeps the soil loose; third, it keeps moisture uniform; fourth, it preserves fertilizer and increases efficiency. It gives full play to the advantages of loose soil and good permeability, so that Ezhu produces many rhizomes, large individual size, high yield and easy harvest [10].

3 Harvesting and processing

3.1 Harvesting

Harvest in November to December of the same year, when the aboveground parts wither. One week before digging, first pull out the withered aboveground stems and leaves, dig out the rhizomes and tuberous roots, shake off the soil, pick out the "old heads", diseased rhizomes and tuberous roots, and bury and destroy them centrally to prevent disease transmission. Stack the leaves in the field for storage, to be used the next year to cover the ridge surface or placed into an organic fertilizer composting pit to rot into organic fertilizer and return to the soil [5]. Pick off the tuberous roots, cut off the fibrous roots on the rhizomes, and pile the rhizomes and tuberous roots separately [11].

3.2 Processing

Wash the rhizomes and tuberous roots, place them separately in a steamer to steam or put them in a pot with water just covering them and boil for 1.5-2.0 h, until steamed or boiled through to the core, then take them out and place them on a clean drying yard to sun-dry until fully dry. After the tuberous roots are sun-dried, they become the commercial product Yujin; after the rhizomes are cut into thick slices and sun-dried, they become the commercial product Ezhu [11]. Alternatively, after steaming until through to the core, put the medicinal material into a drying oven separately according to rhizomes and tuberous roots for drying treatment; the drying temperature should not exceed 50°C, and the drying time is determined by the drying amount and degree of drying, ensuring that the moisture content of the rhizomes does not exceed 14% and that of the tuberous roots does not exceed 15%; after drying is completed, weigh them separately and keep records and labels [5].

3.3 Seed retention techniques

Harvest at the proper time according to the requirements for seed ginger. Stop irrigation one week before harvest, cut off the aboveground stems and leaves, and transport them out of the field in time, to reduce tuber infection and accelerate the suberization of young rhizomes. During harvest, prevent mechanical damage and avoid frost. After digging up the plants from the original seed nursery and the improved variety propagation site, separate the rhizomes, shake off the soil attached to the rhizomes, retain the fibrous roots on the rhizomes, and after removing rhizomes that do not meet specifications, they become the "seed ginger" for sowing in the next year. Seed ginger should be stored properly to prevent mixing, disease and seed rot [5].

3.4 Storage

Chinese medicinal material warehouses must always be kept clean and ventilated, dry, protected from light, and protected against mildew; temperature and humidity must be recorded in real time to ensure compliance with the storage requirements of a temperature not higher than 20°C and humidity of 45% to 75%. The distance between medicinal materials stored on shelves and the walls and roof should be no less than 30 cm, and the distance from the ground no less than 10 cm; regularly check for insect damage, mildew, rot, oil exudation and other phenomena [5].

4 Summary

As a commonly used Chinese medicine, Ezhu has broad application prospects in the export of raw medicinal materials and in food and health care, has great development value, and the economic benefits generated by Ezhu cultivation are considerable; it can serve as a planting demonstration project to drive farmers to become prosperous, and is very attractive [12]. Therefore, by studying the progress of cultivation techniques, standards and methods for the cultivation techniques and management of Ezhu and Ezhu-type medicinal materials in South China can be established, large-scale planting can be carried out, agricultural machinery and agronomy can be combined, the research and development of Ezhu production machinery can be accelerated, and the mechanization of Ezhu production can be gradually realized, ensuring the quality of medicinal materials. This will be conducive to guiding large-scale agricultural production and is of far-reaching significance, thereby improving the yield and economic benefits of Ezhu.

5. Outlook

Although Ezhu cultivation is now standardized, Ezhu cultivation has continuous cropping obstacles, and how to solve the problem of continuous cropping obstacles is an important research topic for Ezhu cultivation in the future. Ezhu usually uses the rhizome as medicine, which leads to a large number of stems and leaves being discarded and wasted; how to make full use of Ezhu stems and leaves is an urgent problem to be solved [13], and how to regenerate organic waste into resources and mechanize cultivation are also future research topics.

Because Ezhu has good anticancer effects, medicines processed with Ezhu as a raw material have already been launched in large quantities, with extremely broad application prospects and huge demand. In present life, with the continuous increase in cancer patients, the amount of Ezhu needed is also increasing, which requires both sufficient raw materials and excellent quality in the future. For this reason, the following aspects still need in-depth research: solving the problem of continuous cropping obstacles in production and reducing land waste; developing and utilizing Ezhu stems and leaves, reducing resource waste, and enabling the recycling of organic waste; establishing reasonable quality evaluation standards or systems to ensure the quality of medicinal materials; and exploring the pharmacological effects of multiple components to provide a basis for new drug development.

How to extend the industrial chain: in developing the medicinal aspect, it will be a new topic of Chinese materia medica in the 21st century to use modern molecular biology techniques to screen and find molecular markers for important traits of medicinal plants, carry out molecular marker breeding of Chinese medicinal materials, artificial regulation of Chinese medicine quality, and production of genetically engineered drugs [14].

References

[1] Ch P (Chinese Pharmacopoeia) [S]. Vol Ⅰ. 2000.

[2] Xu Shibo, Tang Xiaoli. Overview of research on the pharmacological effects of curcumin [J]. Chinese Traditional and Herbal Drugs, 1991, 22(3):140.

[3] Guizhou Flora Editorial Committee. Guizhou Flora (Volume 4) [M]. Chengdu: Sichuan Nationalities Publishing House, 1989:1.

[4] Liu Yinzhang, Yang Yulan. Suggestions on accelerating the development of Chinese medicinal material Ezhu production in Lingshan County [J]. Guangxi Agricultural Sciences, 2006, 22(2):58-59.

[5] Yin Xiaojuan, Liu Zhongjun, Ji Ou, Yang Zhaowu, Yang Sha, Lin Yu, Li Rujie. Standard operating procedure (SOP) for standardized production of Curcuma phaeocaulis [J]. Modern Chinese Medicine Research and Practice, 2014, 28(02):9-12.

[6] Liang Juxiu. Ezhu cultivation techniques [J]. Guangxi Tropical Agriculture, 2006(03):39.

[7] Lao Chuangbo. Ezhu cultivation and processing techniques [J]. Friends of Farmers, 2006(03):32.

[8] Ouyang Shengxiang. Research on nitrogen, phosphorus and potassium nutritional characteristics, optimized fertilization and variety rejuvenation of Curcuma kwangsiensis [D]. Nanning: Guangxi University, 2008.

[9] Liang Juxiu, Liu Xunzhong, Liu Xuqin, Liu Huacai, He Dafu. Effects of different planting techniques on the yield and benefits of the Chinese medicine Ezhu [J]. Modern Agricultural Science and Technology, 2013(04):75-76.

[10] Li Zhenke, Liu Huacai. "Three avoidances" cultivation techniques for Ezhu in Qinzhou City, Guangxi Province [J]. Beijing Agriculture, 2013(18):97-98.

[11] Wu Qinghua, Lin Wei, Ning Quanqiang, Yan De'ai, Huang Mingting. Pollution-free production technical regulations for Ezhu [J]. Modern Chinese Medicine Research and Practice, 2012, 26(02):3-4.

[12] Ye Yonghao, Hao Hong, Cai Yuyi, Yang Liying, Li Shuyuan. Research progress on cultivation, propagation and molecular identification of Curcuma kwangsiensis [J]. Chinese Medicinal Materials, 2015, 38(10):2220-2222.

[13] Wang Deli. Research progress on the Chinese medicine Ezhu [J]. Journal of Anhui Agricultural Sciences, 2014, 42(11):3240-3242+3258.

[14] Li Xiaokun, Yao Chongshun, Huang Yadong, Xiao Jian. Application of modern technology in Ezhu research [J]. Pharmaceutical Biotechnology, 2005(02):134-137.7