Discussion on the efficacy of maca and the current status of cultivation
Lepidium meyenii Walp is an annual or biennial herb of the family Brassicac-eae, native to the Andes mountains of South America at an altitude of 3 500 to 4 500 m, and has been cultivated for thousands of years and is one of the indispensable crops in the region. Maca was originally named Lepidium meyeniiWalp by the German botanist Gerhard Walpers in 1843. Later, Peruvian biologist Gloria Chacon discovered that Peruvian maca differed from what Gerhard Walpers described, and published Peruvian maca as a new species and named it Lepidium peruvianum G Chacon de Pop-ovici. Maca is rich in vitamins and contains alkaloids purified compounds that scavenge the harmful 1, 1-dibenzyl-2-trinitrophenylhydrazine free radicals (DPPH) and hydroxyl radicals (OH). A large number of studies have shown that maca also has the effects of improving fertility, improving sexual function, regulating endocrine, enhancing immunity, antioxidant, anti-stress, anti-fatigue and anti-cancer, and has a good therapeutic effect on rheumatism, respiratory diseases, depression, anemia, etc. Studies have shown that after the identification of maca ingredients, Yunnan Lijiang maca and Peruvian original maca are the closest in appearance, size, and content of functional ingredients. In recent years, due to the excessive speculation of maca, exaggerated its efficacy, serious fraud, misleading consumers and other phenomena, resulting in the maca industry to a trough, on the verge of bankruptcy. This paper reviews the medicinal effects of maca, the current situation of maca cultivation, etc., and looks forward to its prospects.
1 Medicinal properties of maca
Many related studies have shown that maca is rich in active substances, these active substances have a significant effect on improving sexual function and improving fertility, in addition, maca also has antioxidant functions, with certain anti-aging, anti-fatigue and other effects. Studies such as Cha Shenghua have shown that maca extract has a significant fatigue relief effect on sports mice. Miura et al. Have shown that maca helps athletes fight fatigue and enhance endurance. Yu Farong et al. discussed the effect of maca extract on the toxicity and immune organs of mice, and the results showed that maca extract had the effect of increasing the weight of immune organs and improving immune function, and the toxicity was low. Wang Yanwu et al. administered maca to mice with 190, 380 and 760 mg/kg for 30 days after continuous gastric filling, and then performed the determination of various immune indicators, and the results showed that maca had a promoting effect on the increase of mouse antibody production cells (P<0.05, P<0.01), which could improve the ingevicity of mouse mononuclear macrophages and the activity of mouse NK cells (P<0.05). Zhang Yongzhong et al. have shown that maca alcohol extract can significantly improve PHA-induced lymphocyte transformation, promote serum hemolysin production, and increase the production of antibody-producing cells, without significantly affecting the phagocytic function of mononuclear macrophages.
In recent years, the price of maca has been rising, the main reason is due to the ability of maca to improve sexual function. From related studies, maca-mides in maca is considered the main active ingredient in maca to improve sexual function. Since the 1990s, maca has been widely reported on its role in improving fertility in mammals and fish. Modern studies have shown that maca can increase sperm motility, maca alcohol extract and water extract can increase the weight of the testicles, epididymis and sperm production rate, maca can also increase sperm count and motility. Cao Dong et al. have shown that Lijiang maca n-butanol and water extracts have the effect of improving the sexual behavior of male mice, and have nothing to do with sex hormone regulation. Wang Xichen and other studies have shown that maca can improve the mating ability and penile erectile function of semi-castrated rats, and its mechanism may be related to adjusting imbalanced serum sex hormone levels. Zhou Yi et al. studies have also shown that maca polysaccharides can significantly improve the survival rate of fruit flies, accelerate the development rate of fruit flies to a certain extent, and improve the sexual vitality and reproductive ability of fruit flies. Therefore, the internationally recognized effect of maca is to increase libido and improve sexual function.
2 Other benefits of maca
Maca has the effect of regulating endocrine, and it contains alkaloids, sterols, saponins, mustard oleosides, benzyl vinegar isothiocyanate, etc., such as alkaloids can act on the lower part of the thalamus and pituitary gland, regulate endocrine glands, and play an important role in alleviating human menopausal syndrome. In addition, maca can also improve bone metabolism, Peng Lu and other studies have confirmed that maca ethanol extract has a good inhibitory effect on tretinoin-induced osteoporosis. Wang Zhu et al. used animal models of low estrogen to explore the effects of Lepidiummeyemii Walp (commonly known as Maca) on body fat, sex hormones and bone metabolism in female rats, and the results showed that Maca solitary vegetables helped to improve blood lipid abnormalities and bone metabolism after oophorectomy. Maca also has the function of lowering blood lipids, Zhang Yongzhong et al. studied the effect of alcohol extract of South American plant maca on endocrine hormones and blood lipid levels in de-ovary rats, and the results showed that maca alcohol extract has a certain reducing effect on serum cholesterol levels.
Maca is favored by people because of its rich nutritional value and pharmacological effects. Before 2015, Maca was planted in Lijiang, Diqing, Dali and parts of Sichuan, initially forming an industrialization. Maca lozenges, maca essence tablets and other products have successively landed on the market, and their maca active substance extraction process has also been continuously improved. Du Guangxiang et al. studied the effects of four factors of material-liquid ratio, time, temperature and power on the ultrasonic extraction of maca alkaloids, and determined the optimal extraction conditions through orthogonal tests. Tu Xinghao et al. discussed the application effect of high-temperature steam blanching on the passivation of black mustard enzyme in maca root, and the results showed that high-temperature short-term steam treatment can effectively passivate the activity of black mustard enzyme in maca root, and the sensory quality after treatment is better, and the advantages are more obvious than that of conventional blanching process. Xu Juan and others made full use of the residual nutrients and functional ingredients in maca residue after juice extraction, and used maca residue as raw material to explore the best preparation process conditions for maca fruit vinegar. Fan Danmin studied the processing technology of maca health drinks with maca and honey as the main raw materials. Gong Weiguang et al. studied the production process of fermented KVAS beverages using maca and malt as raw materials and determined the optimal production process. Xu Tiancai et al. applied orthogonal test methods to optimize the formula and extraction process of maca worm lotus health wine, and provided theoretical basis and technical means for further improving the quality of its actual production of maca worm lotus health wine.
With the development and utilization of maca's rich pharmacology and other functions, maca by-products have also been coming out, and the cultivation area has also increased, in 2012, the planting area of maca in Yunnan Province reached 22,000 hm 2, and as of 2016, the planting area of maca has increased by 4 to 5 times. Maca has become one of the important cash crops for mountain farmers to get rich in recent years.
3 The current situation of maca cultivation in China
Maca due to the characteristics of improving sexual desire and improving sexual function, is loved by people, since 2002, its price has been rising, China's maca cultivation area is also increasing, showing a rapid development trend.
Maca has strict requirements for climate, suitable for the average annual temperature of 5 ~ 10 °C, the average maximum temperature in September does not exceed 18 °C, high cold tolerance, strong adaptability, can be planted at an altitude of 3 030 m, loose soil, soil permeability and water retention of the slightly acidic sandy soil area. In recent years, maca propagation mainly adopts seed or seed seedling methods, Shang Ruiguang et al. Through seed germination experiments in artificial climate boxes, it is found that in the range of 5 to 30 °C, the time required for maca seeds to begin germination and germination to complete decreases with increasing temperature; 15 to 30 °C is the suitable germination temperature for maca, 15 to 25 °C germination rate is higher, and germination index and germination rate index are the highest at 25 °C. Under the condition of seedling transplanting, Hu Qiang et al. studied the effects of row spacing and plant spacing on maca seed yield and yield traits, and the results showed that row spacing and plant spacing had a significant effect on maca seed yield and yield traits, of which 20 cm×30 cm, 30 cm×20 cm, 30 cm×30 cm, 20 cm× 20 cm row spacing and plant spacing combination of seed yield were ideal, reaching 230.0, 221.5, 203.5, 199.0 kg/hm 2, respectively. Maca is an impotent plant that is generally cultivated on the sunny side. Studies have shown that under conditions of insufficient light, maca yields are low and of poor quality. Yang Puqiu et al. used black maca and yellow maca seeds as materials, and used different concentrations of gibberellin (0, 50, 100, 200, 400 mg/L) to soak the seeds for 24 h to determine the seed germination rate, germination potential, root length and other indicators. The results showed that different concentrations of gibberellin could improve the germination rate, germination index and root length of maca seeds.
Compared with traditional agriculture, plant tissue culture can greatly improve the reproductive rate of maca and realize the industrialization of maca. Zhu Jun et al. studied the effects of different concentrations of hormone combinations on callus induction, bud cluster induction and rooting using the young roots, hypocotyls, cotyledons and budding stem segments of maca sterile seedlings as explants and MS medium as the basic medium. The optimal callus, bud clusters, and rooting induction media were MS+NAA 0.5 mg/L+6-BA 1.0 mg/L, MS+NAA 0.25 mg/L+6-BA 2.0 mg/L, and MS+NAA 0.5 mg/L, respectively. Through tissue culture, Duris et al. induced two kinds of maca with purple and black roots to obtain buds. Zhu Xiumei et al. screened maca tissue seedling rooting medium, and the results showed that in the series of experiments on the rooting formula of maca tissue seedlings, it is advisable to add activated charcoal, and the addition of 30 g/L sucrose to the MS medium has the best effect on the induction of the average rooting rate. Geng Shuxiang et al. conducted screening and anti-browning treatment tests of callant media and proliferative medium of maca seeds and root two explants, and the results showed that the optimal combination of maca seeds or root primary media was 3/4MS+6-BA 3 mg/L+NAA 0.3 mg/L+ sucrose 25 g/L, MS+6-BA 0.3 mg/L+NAA 0.3 mg/L+NAA 0.3 mg/L+ sucrose 25 g/L, respectively, and the optimal combination of seed and spikelet hypertrophied medium was MS+6-BA, respectively 0.3~0.5 mg/L+NAA 0.3 mg/L 、 MS+6-BA 0.3 mg/L+NAA 0.3 mg/L 。
Up to now, the quality inspection of maca seeds has not yet standardized quality standards, and there are no relevant research reports on the domestic operating procedures for the treatment, storage, processing, packaging and other operating procedures of maca seeds and seedlings.
With the continuous growth of the maca industry, the price of maca has been rising steadily, and from 2013 to 2015, the cultivation area of maca has reached its peak. Farmers plant maca on a large scale without considering factors such as climate and soil, resulting in low yields and poor quality of maca. Coupled with the mixed fish in the maca market, fraudulent consumer behavior has been repeatedly prohibited, which eventually leads to consumers losing confidence in maca. After 2016, in just a few years, maca prices fell rapidly, causing the entire maca industry to be on the verge of bankruptcy.
4 Outlook
Maca has certain medicinal value for people and livestock, in order to revitalize the maca market, high-quality varieties of maca should be selected for demonstration planting; the government should actively guide areas suitable for planting maca for fine planting; can operate according to the modern management mode of "company + base + farmer + market"; clarify the functions of relevant government departments, establish and improve the standardization system of maca industry, and promote the healthy development of maca industry.
In addition, other active ingredients of maca can be deeply extracted. Many studies have shown that maca has a certain effect on regulating endocrine, antioxidant, anti-fatigue, anti-cancer and other aspects, but it only stays in the research stage and has not yet been widely used in clinical practice. Therefore, increasing the extraction and utilization of active medicinal substances of maca is one of the important factors for revitalizing the development of the maca industry.