buckwheat
Buckwheat is a crop of buckwheat in Polygonaceae, an annual herbaceous dicotyledonous plant and a cultivated plant in Polygonaceae. Yi people call it "forehead", which was also written as naked oats or rye in ancient times. Sichuan province is used to calling buckwheat seeds. Also known as Hu Qiao.
Panicum miliaceum, with short growth period, strong resistance, extremely cold and barren, can sow and harvest many times in that year. The stem is erect, the lower part is not tillering, multi-branched, smooth, light green or reddish brown, and sometimes has sparse papillae. The leaf center is triangular, the top is conical, and the base is heart-shaped or halberd-shaped, with the whole margin. Stipules sheath is short and cylindrical, with oblique top and early shedding. Inflorescence racemose or conical, terminal or axillary. Small flowers and white flowers bloom in spring and summer; Pedicel slender. The fruit is dry, oval, yellowish brown and smooth. There are many cultivated varieties, especially tartary buckwheat, which has the most nutritional and health care value. Purple stems, triangular leaves, small white flowers, black seeds, ground into flour to eat.
Distributed in Europe and Asia; Cultivated all over China, sometimes wild, born in wasteland or roadside, the seeds are rich in starch, used for food and medicine, and are also honey plants.
Cultivation history
Buckwheat originated in China. Cultivation has a long history. There are four kinds of cultivated buckwheat, namely sweet buckwheat, bitter buckwheat, sweet buckwheat and buckwheat. Buckwheat and tartary buckwheat are two main cultivated varieties. More than 3,000 local varieties were collected, of which buckwheat and tartary buckwheat each accounted for half.
Buckwheat is one of the important food crops and famine relief crops in ancient China. The earliest known buckwheat was unearthed in No.4 Han Tomb in Yangjiawan, Xianyang, Shaanxi, which has been more than 2,000 years. In addition, Ma Quan in Xianyang, Shaanxi Province and Mozizi in Wuwei, Gansu Province also unearthed artifacts before and after the Han Dynasty.
However, before the Tang Dynasty, buckwheat cultivation did not seem to be common. Although there are records of buckwheat in Qi Yao Min Shu ZaShuo, it is generally believed that ZaShuo was not written by the Tang Dynasty. It is said that the "Qumai" attached to Qimai 10 is buckwheat, but this is just a family statement. The most accurate record of buckwheat in agricultural books was first found in Four Seasons Compilation and Sun Simiao's Thousand Women's Children for emergencies. At the same time, buckwheat is also mentioned in related poems. Therefore, it is generally believed that buckwheat was popularized in the Tang Dynasty.
With the popularization of buckwheat cultivation in Tang Dynasty, buckwheat cultivation techniques have also been summarized. Miscellaneous notes are not long, but the records of buckwheat are very detailed. Miscellaneous Notes describes the cultivation techniques of buckwheat for the first time, with special emphasis on timely harvest. "It's all buckwheat. Plow the land in May. 35 days later. When the grass is rotten, you should plant it three times and plow it three times. Beginning of autumn planted them within ten days. If you plow the land three times, you will have three times the load. The lower baryon is black, and the upper baryon is white. They are all white juice, as thick as full, that is, they must be harvested. But the tip should be laid. White is getting darker every day, which is worth it. If it is always dark there, sunspots will be reduced by half. " This shows that people at that time had already understood the mature characteristics and after-ripening function of buckwheat. There is an article about "planting buckwheat" in the Collection of Four Seasons in June: "beginning of autumn planted it in June, that is, the first ten days of autumn, and beginning of autumn planted it in July, that is, the tenth day after autumn. It is appropriate to elaborate on the illness in autumn. " There are not many records about buckwheat cultivation techniques in Song Dynasty, but people in Song Dynasty know a lot about the physiology and ecology of buckwheat. Chen Shidao in the Northern Song Dynasty mentioned the relationship between buckwheat and climate and phenology in "Talk about the Back Mountain", "The Mid-Autumn Festival is dark, and the world is the same. Buckwheat is beautiful on the moon. If there is no moon in the Mid-Autumn Festival, buckwheat is not true. " Zhu Bian described the form and ecology in detail in Old News of Quyi, saying: "Buckwheat has yellow leaves, gray leaves, red stems, black seeds and yellow roots, and also has the color of five sides. However, Fang is most afraid of being strong in first frost. It rains at this time, which is especially suitable for fruit-bearing, and there is no frost. Farmers call it' defrosting rain'. " There was a new understanding of buckwheat cultivation techniques in Yuan Dynasty. First, in terms of sowing quantity and sowing method, it is put forward that "sowing density means more seeds, and sowing sparse means less seeds". Secondly, according to the characteristics of buckwheat easy to drop seeds, the harvesting method was improved and the sickle was used for harvesting. Wang Zhen's agricultural book says, "I'm afraid the seeds will be burnt, but I'll get them by pushing a sickle." The structure and function of pushing sickle are also introduced in detail in the Atlas of Agricultural Machinery. It can be seen that the sickle is the earliest harvester, and buckwheat is the earliest crop harvested mechanically.
The cultivation of buckwheat is relatively simple. Because its whole growth period is very short. After the main crop is harvested, a mature buckwheat can be replanted, which not only increases the multiple cropping index, but also facilitates rotation with other crops. This situation was very common in the Ming and Qing Dynasties. "Tiangong Kaiwu" said that "all buckwheat must be cut south, and millet must be cut north before planting". The Farmland Manual also says that after harvesting millet, "the land should be planted with wheat". Ma Shou Nong Yan also said that "there are many kinds of buckwheat in the wheat field this year". The Ming Dynasty's "Ying Ying Yue Ling" and the Qing Dynasty's "Brief Book of Disaster Relief" both pointed out that buckwheat can be mixed with alfalfa, and the alfalfa will take root and grow by itself the next year after cutting buckwheat. "Nongsang Jing" advocates that "there are many fields and rapeseed is planted every year".
Buckwheat, as a traditional crop, is widely planted all over the world, but its proportion in food crops is very small. Buckwheat in the world mostly refers to sweet buckwheat. Buckwheat is regarded as a wild plant abroad and is also used as feed. Only China has the habit of cultivation and eating. The global buckwheat planting area is 7-8 million hectares, with a total output of 5-6 million tons. The main producing countries are the former Soviet Union, China, Poland, French, Canadian, Japanese and Korean. The former Soviet Union is a major buckwheat producer in the world, with an planting area of about 3-4 million hectares, accounting for nearly half of the world's total planting area, with an average yield of about 6 15kg per hectare and a total output of about 2 million tons. The planting area and yield of buckwheat in China ranks second in the world. In the 1950s, the planting area reached 2.2 million hectares, with a total output of 900,000 tons and an average yield of 405 kilograms per mu. However, due to the biological characteristics of buckwheat and farmers' long-term planting habits, buckwheat in China has always been regarded as a disaster relief crop in the past, with extensive planting, low yield, disjointed production and low commodity rate, which is not conducive to the development of agricultural production and the promotion of high-yield crops. Recent studies in agriculture, medicine and food nutrition show that buckwheat, especially tartary buckwheat, has the highest nutritional value among all food crops. It is not only rich in nutrients and high in nutritional value, but also contains special trace elements and medicinal components that other food crops lack and do not have. It has the function of preventing and treating modern "civilized diseases" and almost all cardiovascular and cerebrovascular diseases of middle-aged and elderly people, so it has attracted the attention of all countries. The production of buckwheat and the development of health food show a new development momentum, and the status of buckwheat in world trade is also improving. According to the incomplete statistics of 1986, the planting area of buckwheat in 20 provinces and regions in China is 722,000 hectares, with a total output of 5 1 10,000 tons and an average yield of 705 kilograms per hectare. Among them, tartary buckwheat is about176,000 hectares, with a total output of 220,000 tons, with an average yield of 1249.5 kg per hectare; There are 546,000 hectares of buckwheat with a total output of 290,000 tons, with an average yield of 53 1 kg per hectare.
Liangshan Prefecture is one of the concentrated buckwheat producing areas in Sichuan Province. As the main grain crop in the mid-level area of Liangshan Prefecture, the annual planting area is 60,000 hectares, including 48,000 hectares of tartary buckwheat, with a total output of 1 1 10,000 tons, accounting for about 1/2 of the national output. Quanzhou has 70,000 hectares of arable land suitable for buckwheat cultivation. Buckwheat products have great development potential. As a raw material base, it can provide tens of millions of kilograms of commercial buckwheat to processing enterprises every year.
Production significance
1. Agricultural status
Buckwheat has a short growth period, generally only 70 to 90 days from planting to harvesting, and early-maturing varieties can be harvested in more than 50 days. Buckwheat has wide adaptability, strong stress resistance and rapid growth and development, and has a special position in crop layout: ① Buckwheat is produced in the vast dry farming areas and alpine mountainous areas with short frost-free period, less and concentrated precipitation, and water and heat resources can not meet the needs of large food crops; (2) In agricultural areas with long frost-free period, less land per capita and extensive farming, buckwheat is used as a continuous cropping crop; (3) After natural disasters such as drought and flood, buckwheat seedlings died or the main crops failed, which is an important crop for disaster relief; ④ Buckwheat green pressing is one of the measures to improve light sandy soil, which can increase the organic matter and nutrients in the soil; ⑤ Buckwheat can also convert insoluble phosphorus in the soil into soluble phosphorus, and can also convert insoluble potassium into soluble potassium, and leave it in the soil for later absorption and utilization.
Buckwheat can emerge 3 ~ 5 days after sowing, and it grows rapidly, and most weeds can be inhibited after sealing. Planting buckwheat saves time and effort. In terms of agricultural schedule, buckwheat usually ranks behind other crops from ploughing, sowing to management. We can adjust the farming season, comprehensively arrange agricultural production, and realize the economic benefits of low input and high output. With the advancement of scientific research and industrial development of buckwheat in China, the status of buckwheat in agricultural production is changing from "disaster relief and replanting" crops to economic small crops for farmers to get rid of poverty and become rich.
2. Nutritional value
Buckwheat is rich in nutrition. According to the analysis, its grain contains protein 7.94 ~ 17. 15%, fat 2.00 ~ 3.64%, starch 67.45 ~ 79. 15% and cellulose1.04 ~1. Japanese scholars reported that the nutritional potency index of buckwheat was 80 ~ 92 (70 for wheat and 50 for rice).
According to the analysis of the nutritional components of main grains in China by the Institute of Health of China Academy of Medical Sciences, the protein content of buckwheat flour is obviously higher than that of rice, millet, wheat, sorghum, corn flour and Ciba. Buckwheat flour contains 18 kinds of amino acids, and its amino acid composition is similar to that of bean crop protein. The fat content is also higher than that of rice, wheat flour and Ciba. Buckwheat fat contains 9 kinds of fatty acids, among which oleic acid and linoleic acid are the most, accounting for 75% of the total fatty acids, and also contains palmitic acid 19% and linolenic acid 4.8%. In addition, it also contains organic acids such as citric acid, oxalic acid and malic acid. Buckwheat also contains trace elements such as calcium, phosphorus, iron, copper, zinc, selenium, boron, iodine, nickel and cobalt, and various vitamins: Vb, Vb2, Vc, Ve, VPP and VP, among which VP (rutin) and chlorophyll are not contained in other cereal crops. The nutritional components of buckwheat seeds vary with varieties and cultivation conditions. These substances play an important role in the physiological metabolism of human body. With the development of modern science and technology, the improvement of people's quality of life and the quality and diversification of food, buckwheat as a healthy food will be favored by people.
3. Feeding value
Buckwheat seeds, hulls, straws and silage can be used to feed livestock and poultry, while broken grains, rice bran and hulls are widely used as livestock feed. Buckwheat crumbs are precious feed, rich in minerals such as fat, protein, iron, phosphorus, calcium and vitamins, and their nutritional value is 70% of that of corn. It is reported that feeding poultry with buckwheat grains can improve the laying rate and accelerate the growth of chickens. Feeding cows can improve the quality of milk; Feeding pigs can increase solid fat and improve meat quality. Compared with other feed crops, buckwheat has a shorter growth period, which can be sown directly in areas with short frost-free period or repeatedly in areas with long frost-free period, and can provide a large number of high-quality green feed in a short time.
4. Honey crops
Buckwheat is one of the three honey crops in China. Sweet buckwheat has large flowers, many flowers, long flowering period, developed nectaries, fragrance and large amount of honey secretion. Planting buckwheat in a large area can promote the development of beekeeping and diversified management, and also improve the fertilization rate and seed setting rate of buckwheat. The yield of buckwheat Tian Fang bee can be increased by 20-30% or more.
5. Edible value
Buckwheat is a very popular food in northeast, north, northwest, southwest of China, Japan, Korea and the former Soviet Union. Buckwheat food is directly processed from buckwheat rice and buckwheat flour. Buckwheat rice is often used to make buckwheat rice, buckwheat porridge and buckwheat slices. Like other flours, buckwheat flour can be made into noodles, pancakes, bread, cakes, buckwheat cakes, bean jelly, blood cakes and enemas. The Japanese like buckwheat noodles very much, and there are about 5,000 buckwheat noodle restaurants in China. Buckwheat can also be used to make wine, and the color is clear after long-term drinking, which is beneficial to physical fitness. The nutrition in buckwheat leaves is also very rich, and the research on the development of buckwheat leaves at home and abroad is in the ascendant. Some use dried leaves to make buckwheat tea, while others use buckwheat seedlings as vegetables.
6. Earn foreign exchange through export
Buckwheat is a traditional export commodity in China. China buckwheat enjoys a high reputation in the international market for its "big grain, thin skin and high quality", which is mainly exported to Japan and related European countries. In recent years, due to the progress of scientific research, there has been a new understanding of the medicinal value of buckwheat, and various provinces and regions have gradually shifted from exporting raw grain to deep-processed products. The price of buckwheat is relatively high in the international market, but the annual export volume of buckwheat in China is less than one tenth of the demand in the international market, so buckwheat is a tight material in foreign trade export.
7. Utilization of by-products
Buckwheat is rich in nutrition, which can not only provide people with food, livestock grass, poultry feed and honey source, but also prevent and treat diseases and keep fit. Buckwheat husk has always been a good material for making pillows. Long-term use of buckwheat husk pillows has the effect of clearing away heat and improving eyesight. Modern research shows that the content of potassium carbonate in buckwheat husk ash is about 4.6%, and the content of rutin in buckwheat husk is as high as 30%. At present, the export price of buckwheat husk is higher than that of buckwheat, which is estimated to be mostly used in medicine and industrial development research, and the project of deep processing and comprehensive utilization of buckwheat is promising. In recent years, the industrial development of buckwheat, especially tartary buckwheat, occupies a leading position in the world in food, brewing, medicine and other fields, and the export value of products is several times to dozens of times higher than that of raw grain exports.
Buckwheat is considered as a new crop in the world because of its unique nutritional value. It is a small crop, but it can make up for the advantages of large crops and the disadvantages of components it does not have: it can be planted in cold areas with short growth period and poor soil where large crops cannot be planted. It not only contains nutrients contained in large crops, but also contains components necessary for human body that large crops do not contain. Buckwheat is full of treasures, and tender branches and leaves, stems and leaves, flowers and fruits, root stalks and bran rice flour are not wasted. From the utilization of natural resources to raising land and increasing production, from agriculture to aquaculture, from food industry to light chemical production, from food (food and medicine are homologous) to health care and disease prevention, from domestic market to international market, especially in the growing tourism industry in Aba Prefecture, there is a market prospect that cannot be underestimated, and buckwheat will show its unique economic value in characteristic agriculture. Therefore, vigorously developing buckwheat production, transforming buckwheat resource advantages into commodity advantages, and increasing production and income are of great practical significance for improving people's living standards, preventing diseases, promoting rural economic development and getting rid of poverty and becoming rich in high mountains.
nutritive value
(1) nutritional quality
Buckwheat is rich in nutrition, whether it is sweet buckwheat or bitter buckwheat, whether it is grain or stem, leaf or flower, its nutritional value is very high. Comparison of nutritional components between buckwheat and other major cereals (table 1).
It can be seen from the table 1 that the protein and fat of tartary buckwheat flour are higher than those of wheat flour and rice. Protein is also higher than corn flour, but the fat is lower than corn flour. Vitamin B2 is 4 ~ 24 times higher than wheat flour, rice and corn flour, but cereals lack rutin and chlorophyll. Mineral nutrients are also higher than other grains to varying degrees. Tartary buckwheat contains protein 9.3% ~ 14.9%, fat 1.7% ~ 2.8% and starch 63.6% ~ 73. 1, which varies greatly with varieties, planting areas and grain freshness. Compared with buckwheat, protein of buckwheat is 665438 0.5%, fat is 56.9%, vitamin B2 is 3.65438 0.6 times, and vitamin P is 65438 0.3.5 times.
(2) Nutrition distribution
Seeds with or without seed coat obtained by shelling buckwheat fruits are called buckwheat rice, sweet buckwheat rice and buckwheat rice. Buckwheat fruit or buckwheat rice can be ground into buckwheat flour to make food. Like wheat, rice and other bulk grains, the distribution of nutritional components of buckwheat rice gradually decreases from the periphery to the center, that is, the nutritional components in the outer layer are the highest, and gradually decrease inward, reaching the lowest in the center. When buckwheat rice is processed with whole flour, outer flour and heart flour respectively, the nutritional components gradually decrease from the periphery to the center (Table 2).
As can be seen from Table 2, the outer layer powder is close to the seed coat, with high nutrient content, especially vitamin P (rutin) and chlorophyll, which are not contained in other grains.
(3) Nutritional components
1, protein
The protein composition of tartary buckwheat is different from other cereal crops, and its albumin and globulin contents are higher, accounting for 46.93% of the total protein, while the gliadin and glutenin contents are lower, accounting for 3.29% and 15.57% respectively, which are only110 and1/of wheat. The residual protein is 34.32%, which is 12.7 times that of wheat flour (Table 3). The difference between buckwheat flour and wheat flour, two protein ingredients, leads to the different processing characteristics of flour food. The gluten content of tartary buckwheat flour is very low, which is similar to bean protein. Because of rice, wheat and corn, the total amount of protein is low.
(1) amino acids: Tartary buckwheat contains 19 kinds of amino acids, which are not only high in content, but also good in composition. The amino acid content of tartary buckwheat per 10g is 5. 1 16 1g, which is 50.42% higher than that of wheat (3.40 1g). It is17.82% (4.3424g) higher than that of rice. 9.95% higher than that of corn (4.653g); It is 6 1.28% higher than buckwheat (3. 172 1g). Among amino acids, histidine and arginine are essential for adults and children. Taking arginine as an example, the content of tartary buckwheat per 100g is 1.0 14g, which is 2.36 times that of wheat 0.429g, rice 0.745g 1.36 times that of corn 0.47g. ..
Among the eight essential amino acids, the content of tartary buckwheat is higher than that of wheat, rice, corn and buckwheat. In particular, it is rich in lysine, which is most easily lacking in cereal crops. The content of tartary buckwheat is 2.8 times that of wheat, 1.9 times that of corn, 1.8 times that of rice and 1.6 times that of buckwheat. The tryptophan content of tartary buckwheat is 2.4 times that of corn, 1.7 1 times that of sweet buckwheat and 1.6 times that of wheat, which is higher than that of rice 15%.
(2) Quality of protein: High-quality protein is protein with rich content and proper amino acid ratio. At present, "chemical score" is commonly used as the nutritional value of protein in the world. The higher the chemical score, the easier it is for protein to digest and the higher the quality. The protein composition of eggs is close to the optimal amino acid composition needed by human body, and the chemical score is 100. The nutritional values of tartary buckwheat flour, wheat flour, soybean flour and corn flour were compared with eggs as the amino acid composition standard (Table 4).
As can be seen from Table 4, the eight essential amino acids in tartary buckwheat flour are closest to eggs, and the contents of lysine, phenylalanine and tryptophan are higher, but methionine is slightly lower than corn flour, but it is also 55% of eggs and much higher than 40% of wheat flour and corn flour. The chemical score of tartary buckwheat is 55, which is higher than that of wheat 38, rice 49 and corn 40, so the protein quality of tartary buckwheat is of high value in cereals.
Hans (M.HAAS, 1994) of the European Union thinks that buckwheat protein has high nutritional value, and its chemical score is 8 1, which is higher than that listed in Table 4. Moreover, there is a new amino acid "yeast amino acid" in lysine complex.
2. Fat
Tartary buckwheat has a high fat content of 2. 1% ~ 2.8%, which is solid at room temperature, yellow-green, tasteless and different from ordinary grains. Tartary buckwheat has a good fat composition, containing 9 kinds of fatty acids, the most of which are highly stable and antioxidant unsaturated fatty acids oleic acid and linoleic acid, accounting for 87% of the total fatty acids (Table 5).
In addition, tartary buckwheat also contains stearic acid, myristic acid and unknown acid. Stearic acid is 2.5 1%, and myristic acid is 0.35%. The fatty acid content of tartary buckwheat varies from place to place.
3. Starch and dietary fiber
The starch content of tartary buckwheat seeds varies with regions and varieties. The starch in buckwheat is similar to rice starch, but the granules are larger. Compared with ordinary grain starch, buckwheat starch is easily digested and absorbed by human body after eating.
Buckwheat flour contains 3.4% ~ 5.2% dietary fiber, in which soluble dietary fiber accounts for about 20% ~ 30% of the total dietary fiber, about 0.68 ~ 1.56%, which is 8% higher than corn flour and 60.39% higher than buckwheat flour, which is 1.7 times that of wheat flour and 3.5 times that of rice. A survey of Yi people in Liangshan Prefecture, Sichuan Province, shows that eating tartary buckwheat can reduce the contents of serum total cholesterol and low-density lipoprotein cholesterol, which is presumed to be dietary fiber in tartary buckwheat. Of course, tartary buckwheat dietary fiber also has the function of binding amino peptides.
According to recent research, the role of digestible starch in human nutrition is similar to that of dietary fiber. According to the results of hydrothermal treatment of starch by Slovenian Professor I. kreft, buckwheat can be used as a good supplementary diet for diabetic patients, because compared with wheat bread, buckwheat starch after hydrothermal treatment can obtain slowly released glucose and a relatively high proportion of digestible starch.
4, vitamins
Tartary buckwheat powder contains a lot of vitamins: vitamin B 1, vitamin B2, vitamin PP and vitamin P, among which B vitamins are rich. Vitamin B 1 and vitamin PP are significantly higher than those of rice, and vitamin B2 is also 0 ~ 4 times higher than that of wheat flour, rice and corn flour, which has the functions of promoting growth, promoting digestion and preventing inflammation. Buckwheat also contains vitamin B6, and the vitamin B6 of tartary buckwheat is about 0. 02 mg/g ..
Buckwheat contains vitamin P (rutin) and vitamin C that other grains do not have. Rutin is a polyphenol derivative, which belongs to rutin and is a bioflavonoid. It and nicotinic acid (vitamin PP) have the effects of reducing blood lipid, improving capillary permeability and vascular fragility. Vitamin p and vitamin c coexist. The content of vitamin P in buckwheat powder is as high as 6% ~ 7%, while that in buckwheat is only about 0.3%, with a difference of more than 20 times. The content of vitamin C in tartary buckwheat is 0.8 ~ 1.08 mg/g, and the content of vitamin E which can promote cell regeneration and prevent aging is1.347 mg/g. ..
5, mineral nutrients and trace elements
Buckwheat powder contains a variety of mineral nutrients, which has attracted people's attention to human function and food nutrition. As we all know, tartary buckwheat is an important source of essential nutritional mineral elements such as magnesium, potassium, calcium, iron, zinc, copper and selenium. The high content of magnesium, potassium and iron shows the nutritional and health care function of tartary buckwheat powder.
The magnesium in tartary buckwheat is 4.4 times that of wheat flour and 3.3 times that of rice. Magnesium participates in energy conversion of human cells, regulates myocardial activity, promotes fibrinolysis, inhibits thrombin generation, lowers serum cholesterol, and prevents arteriosclerosis, hypertension and heart disease.
Potassium in tartary buckwheat is 2 times that of wheat flour, 2.3 times that of rice and 1.5 times that of corn flour. Potassium is an important cation to maintain water balance, acid-base balance and osmotic pressure in the body.
Tartary buckwheat is rich in iron, the content of which is 2 ~ 5 times that of other bulk grains, which can fully meet the human body's demand for iron, make heme and prevent the occurrence of iron deficiency anemia.
The calcium in tartary buckwheat is natural calcium, and its content is as high as 0.724%, which is 80 times that of rice. Adding tartary buckwheat powder to food can increase the calcium content.
The relationship between zinc and taste disorder is significant.
Tartary buckwheat also contains selenium, which has antioxidant and immunomodulatory functions. It can combine with metals to form an unstable "metalloselenoprotein" complex in human body, which helps to eliminate toxic substances in the body. Buckwheat is praised as a valuable selenium-enriched resource by the national germplasm bank. Selenium is an essential trace element determined by the United Nations Health Organization, and it is the only anti-cancer element recognized by the organization at present. Medical research at home and abroad has confirmed that selenium deficiency in human body will cause dysfunction of important organs, and there are more than 40 diseases related to selenium deficiency in diet. Medical experts at the American Cancer Institute point out that moderate selenium can prevent almost all cancers. The United States advocates a daily selenium intake of 200μ g per person. In China, because 765,438+0% areas are low in selenium or lack of selenium, the China Nutrition Society recommends a daily selenium intake of 50μg per person. At present, the survey results in Beijing, Taiyuan and other big cities are mostly below 50μg, and the sources of selenium in foreign foods are mostly inorganic selenium added to feed and converted, which is secondary absorption in the food chain. Buckwheat selenium is a natural organic selenium, which is based on green plants, so it is very precious and has broad development prospects.
6. Others
Tartary buckwheat also contains more 2,4-dihydroxy cis-cinnamic acid, which contains substances that inhibit skin melanin production and has the function of preventing senile plaques and freckles. It also contains protein's blocking substance, which can block the proliferation of white blood cells.
morphological character
1. root
It is a taproot system with a thick, vertically downward-growing main root, lateral roots and hairy roots. Adventitious roots can also be produced at the base of stems or on stems crawling on the ground. Roots are usually buried at a depth of 30-50 cm.
Step 2 stop
Most species have erect stems, and some perennial wild species have creeping branches at the base. The stems are smooth, hairless or fluffy, round, slightly angular, solid when they are young and mature. The stem diameter is generally 0.4 ~ 0.6 cm, and the stem height is 60 ~ 150 cm, up to 300 cm. There are swollen nodes, and the number of nodes varies with species or varieties, ranging from 10 to 30. The stem color is green, purplish red or red. The stem can form branches, and the number varies with species, varieties, growing environment and nutritional status, generally 2 ~ 10. Perennial plants have large bulbs or rhizomes.
Step 3 leave
Leaves include leaves and petioles. The leaves are kidney-shaped, the base is slightly concave, and there are palmately reticulated veins; The petiole is slender. True leaves are divided into three parts: leaves, petioles and leaf sheaths. Simple leaves, alternate, triangular, ovoid, halberd or linear, slightly angular, entire, palmately reticulate. The size of different types of blades varies greatly. Annual species are generally 6 ~ 10 cm long and 3.5 ~ 6 cm wide, with longer petioles in the middle and lower parts, shorter petioles in the upper leaves and almost no petioles at the top. Stipules sheath membranous, sheathlike and phimosis.
4. flowers
It is a limited and infinite mixed inflorescence, terminal and axillary. Cluster spiral cymes, which are in the shape of racemes, panicles or corymbs, are inserted on the inflorescence axis or branch inflorescence axis.
5. flowers
Most of them are bisexual flowers. Single quilt cover, corolla, generally 5 pieces, only connected to the base, green, yellow-green, white, rose red, red, purple and so on. Stamens are not extended or slightly exposed, usually 8 in two rounds: 3 in the inner wheel and 5 in the outer wheel. 1 pistil, three carpels united, superior ovary, 1 room, 3 styles, capitate stigma. Nectaries are usually 8, developed or degenerated. There are patterns with equal length of pistils and stamens, and there are also patterns with long style, short stamens and short style and long stamens.
fruit
Most of them are triangles with at least two irregularities. Shapes are triangular, oval, etc. The tip is tapered, and there are 5 cracks at the base of the persistent perianth. Whether there are longitudinal grooves on the edge of fruit, smooth or rough peel, color change and whether there are wings or thorns are the main characteristics to distinguish species and varieties. There is a seed in achene, the embryo is hidden in endosperm, and the leaves are opposite.
Growth condition
1. temperature
Buckwheat is a thermophilic crop, and its growth period needs accumulated temperature above1100 ~ 2 100℃. The optimum temperature for buckwheat seed germination is 15 ~ 30℃. 4 ~ 5 days after sowing, seedlings can emerge neatly. The optimum temperature of growth stage is 65438 08 ~ 22℃; During flowering and fruiting, cool climate and relatively humid air are beneficial to the increase of yield. When the temperature is lower than 13℃ or higher than 25℃, the plant growth is obviously inhibited. Buckwheat is weak in cold tolerance and afraid of frost, so one of the key measures to cultivate buckwheat is to master the appropriate sowing date according to the local accumulated temperature, so that the growth period of buckwheat is in a warm climate, and the flowering and fruiting are in a cool climate to ensure maturity before frost.
Step 2: Moisture
Buckwheat is a wet-loving crop, which needs about 760 ~ 840 cubic meters of water for a lifetime, which is more expensive than other crops. Weak drought resistance. The water consumption of buckwheat in different growth stages is also different. The water consumption of seed germination is about 40 ~ 50% of the seed weight, and insufficient water will affect germination and emergence; After budding, the plant volume increased and the water consumption increased sharply. The water consumption from fruiting to maturity accounts for about 89% of the whole growth stage of buckwheat. The key period of buckwheat water requirement is the tetrad formation period of pollen mother cells 17 ~ 25 days after emergence. If there is drought and high temperature during flowering, pollination will be affected and nectar secretion will be less. When the atmospheric humidity is lower than 30 ~ 40% and there is hot air, plants will wither and flowers, ovaries and formed fruits will fall off. In foggy and rainy climate, the pollination and fruiting of buckwheat will also be affected.
3. sunshine
Buckwheat is a short-day crop, sweet buckwheat is sensitive to light, and bitter buckwheat is not strict with light, so it can grow and form fruits under long and short sunshine conditions. In the early growth stage from emergence to flowering, it is suitable to grow under long sunshine conditions; In the late growth period from flowering to maturity, it is suitable to grow in short sunshine. Long sunshine promotes vegetative growth of plants, while short sunshine promotes development. The same variety blooms late in spring sowing and has a long growth period; Sowing and flowering in summer and autumn are early, and the growth period is short. Different varieties have different responses to sunshine length, and late-maturing varieties are more sensitive than early-maturing varieties. Buckwheat is also a light-loving crop, and its response to light intensity is more sensitive than other cereal crops. Insufficient light at seedling stage, thin plants; If there is insufficient light during flowering and fruiting, the flowers and fruits will fall off, the fruiting rate will be low and the yield will be reduced.
4. nutrients
Buckwheat generally needs more phosphorus and potassium as nutrition. The application of phosphorus and potassium fertilizer has a significant effect on improving buckwheat yield; Too much nitrogen fertilizer, vigorous nutrition growth, "top-heavy", easy to cause lodging in the later stage. Buckwheat is not strict in choosing soil. As long as the climate is suitable, any soil that is not suitable for planting other cereal crops, including barren, acidic or newly reclaimed land, can be planted, but sandy soil with good drainage is the most suitable. Soil with heavy acidity and alkalinity can be planted after improvement.
China is one of the origin centers of buckwheat, which has a long cultivation history and rich cultivation experience. However, due to the long-term neglect of buckwheat's position in crop distribution, the research on buckwheat in China was still blank before 1980s. Although it started late, it developed rapidly, especially in the research of cultivation techniques. In short, in order to achieve high yield of buckwheat, six changes should be made: changing stubble into good stubble and good land; Change extensive farming into intensive farming; Change sowing into drilling and reasonable close planting; Changing non-fertilization into scientific fertilization; Change farm varieties into excellent varieties; Change only planting, regardless of refined management.
cultivation techniques
1. Seed selection
Selecting improved varieties is the first choice with less investment, quick effect and high yield. There are many varieties of buckwheat in Aba Prefecture, each with different adaptability, so it is necessary to adapt to local conditions. The main cultivated varieties are purified and rejuvenated local varieties and bred "Chuanqiao 1" and "Xiqiao 1". Middle and late maturing varieties with strong stress resistance and high yield performance, such as "Tartary Buckwheat", "Fine Buckwheat", "Chuanqiao 1" and "Xiqiao 1", can obtain higher yield. In the second half of senior high school, stable yield can be obtained by selecting cold-resistant and barren-tolerant varieties such as Xiqiao 1 and pig excrement buckwheat. Choose Chuanqiao 1, Xiqiao 1, Tartary Buckwheat, Shuiqiao and other early, middle and high-yield varieties in the second and middle mountainous areas.
2. Selecting stubble and preparing soil
(1) stubble selection
Rotation system is an important part of farming system. Crop rotation, also known as crop rotation, refers to planting different crops in a certain order on the same plot in a certain period of time to adjust soil fertility, prevent diseases, weeds and insects, and realize high and stable yield of crops. "Planting crops like fertilizing" illustrates the importance of crop rotation. Continuous cropping leads to the decline of crop yield and quality, which is not conducive to the rational use of land. Buckwheat is not strict about the choice of stubble. Any stubble can grow, but continuous cropping is prohibited. In order to obtain high yield of buckwheat, it is best to choose good stubble in rotation. The better crops are beans and potatoes, both of which are land crops. Followed by corn, wheat and vegetable stubble, which are land crops and the main stubble of buckwheat.
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