Cassava（Manihot esculentaCrantz），Woody plant of Cassava in Euphorbiaceae, with cylindrical tuberous roots;The leaves are papery and nearly round;Sepals are purplish red with hoarfrost, and white hairs are attached to the top of anthers;The fruit is cotton round;The seed coat is hard shelled, striped, smooth, and the flowering period is from September to November.[7]Cassava root tubers are used for food. The name is related to its characteristics.[8]
Cassava is native to Brazil and is now widely cultivated in tropical regions all over the world. It is cultivated in Fujian, Taiwan, Guangdong, Guangxi, Hainan, Yunnan and Guizhou provinces and occasionally wild.[7]Cassava has strong adaptability. It is drought resistant, barren tolerant, and has few diseases and insect pests. It does not choose soil, but it is better to plant cassava in deep and loose soil for high yield,[9]It often grows in the mountain sparse forest and is also cultivated in the garden.[10]The propagation mode is stem cutting propagation.[11]
According to Xinhua Materia Medica, cassava can treat carbuncle, sore, blood stasis, pain, scabies, persistent ringworm and other symptoms. With the continuous in-depth study of bioactive ingredients in cassava roots, stems and leaves, people found that cassava has many health functions,[12]In the Compendium of Guangxi Ethnic Medicines, the general manifestations of poisoning are recorded: dizziness, nausea, vomiting, fatigue, sometimes abdominal pain, diarrhea, mouth saliva, severe spasticity, coma, dilated pupils, and death due to respiratory paralysis after the onset. "Therefore, it is only for external use, not for internal use.[13]Cassava root tubers are rich in starch for food or paste, known as the "king of starch", and are the food rations of nearly 600 million people in the world;Stems and leaves can be used as fodder.[11]According to statistics, 65% of the world's total cassava production is used for human consumption. It is the main food source for low-income farmers in tropical wetlands and has high economic value.[12]
Cassava and its relatives are lowland tropical shrubs, which originated in tropical America.It has a cultivation history of about 4000 years.It was introduced and cultivated in China in the 1920s.
In 1588, the Portuguese brought cassava from Brazil to the west coast of Africa, and began to cultivate it in the Gulf of Guinea and the Congo River Basin. In the middle of the 18th century, people introduced cassava to Madagascar and the east coast of Africa. It was only in the middle of the 19th century that cassava gradually expanded, and now it has been distributed in the vast areas of Africa at 15 degrees north and south latitudes.
In the 18th century, Spanish merchants introduced cassava to India for cultivation. At the same time, Indonesia and the Philippines also introduced cassava from Mexico,
Mauritius was introduced from Indonesia in 1740, cassava was introduced to Sri Lanka in 1786, and then cassava was introduced from Indonesia to Malaysia and other Southeast countries.[14]
Leaf:Cassava leaves are papery, nearly circular in outline, 10-20 cm long, palmately divided to the base, 3-7 lobes, oblanceolate to narrow elliptic, 8-18 cm long, 1.5-4 cm wide, gradually pointed at the top, entire, and 7-15 lateral veins (5~);Petiole 8~22cm long, slightly peltate, with inconspicuous ribs;Stipules triangular lanceolate, 5-7 mm long, entire or with 1-2 setose cracks.[3]
FLOWER:Cassava is terminal or axillary panicle, 5-8 cm long,BractStrip shaped lanceolate;The calyx is purplish red with white powder frost;male flower:calyxIt is about 7 mm long, the lobes are long ovate, nearly equal, 3~4 mm long, 2.5 mm wide, and the inner surface is hairy;Stamens 6~7 mm long, with white short hairs on the top of anthers;Female flower: calyx about 10 mm long, lobes oblong lanceolate, about 8 mm long, about 3 mm wide;Ovary ovate, with 6 longitudinal spindles, stigma outward curved, folded fan-shaped.[3]
fruit: Cassava fruit is elliptical, 1.5~1.8 cm long, 1~1.5 cm in diameter, rough surface, with 6 narrow and wavy longitudinal wings;The seed is about 1 cm long, more or less triquetrous, the seed coat is hard crusty, striped, smooth.Flowering from September to November.[3][16]
FLOWER
stem
leaf
fruit
Cassava tuber
Pruning
Distinction of recent species
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cassava
Dioscorea cirrhosa
Bean tuber
Potato
The root of the block is cylindrical.
The tuber generally grows in the topsoil layer, which is egg shaped, spherical, oblong or gourd shaped. The outer skin is dark brown, uneven, red when the section is fresh, purple black after drying, and even up to 20 cm in diameter.
Roots are massive, spindle shaped or oblate, generally 20-30 cm in diameter, fleshy.
Stem block is oblate or 15-80 cm high, spherical, glabrous or sparsely pubescent;It is oblong, about 3-10 cm in diameter, with white, reddish or purple skin.
cassava
Dioscorea cirrhosa
Bean tuber
Potato
Growth environment
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Cassava has strong adaptability. It is drought resistant, barren tolerant, and has few diseases and insect pests. It does not choose soil, but it is better to plant cassava in deep and loose soil for high yield,[9]It often grows in the mountain sparse forest and is also cultivated in the garden.[10]
Distribution range
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Cassava originated in Brazil and is now widely cultivated in tropical regions of the world.Fujian, Taiwan, Guangdong, Hainan, Guangxi, Guizhou, Yunnan and other provinces and regions in China are cultivated, and occasionally become wild (originally introduced and cultivated artificially, and gradually propagated naturally in the wild).[3]
Introduced and cultivated in China in the 1920s, Guangdong Province and Guangxi Zhuang Autonomous Region now have the largest cultivation area.[2]
Edible cassava generally needs to be planted in areas where the frost free period is about 8 months and the annual average temperature is 18 ℃ or above.The production environment of pollution-free cultivation of edible cassava should meet the requirements of DB45/T410.[1]
Land selection and preparation
Cassava should be planted on flat or gently sloping sandy soil land with good drainage. If the planting land is mature, it needs to be rotated for 2 or 3 years. Peanut, corn, soybean, mung bean and other crops are preferred.Land preparation shall be carried out about one month before planting, usually with two ploughs and two harrows, and the appropriate depth of cultivated land is 30~40cm to make the soil flat and loose.[1]
Variety selection
Cassava should be selected for its low content of hydrocyanic acid (below 100mg/kg), high yield, disease and insect resistance, and strong stress resistance.China mainly has local bread cassavaSouth China 9, South China 6068, South China 12 and GR891.[1]
plant
The suitable planting time of cassava in China is from February to April. The main stems that are fully mature, 2-4cm in stem diameter, dense nodes, no damage to stem bark and bud eyes, and no pests and diseases should be selected. The upper part of each seed stem should be removed, the middle and lower seed stems should be retained, and the length should be cut to 15-20cm.Four planting methods can be adopted, namely, horizontal planting, oblique planting, straight planting and flat planting. It is better to adopt ridging and film covering horizontal planting or ridging and open horizontal planting. The eye bud direction should be unified. The row spacing of planting plants should be 0.8m × 0.8m or 1m × 0.8m.[1]
Cassava seedlings
Field management
Replenishment and thinning
The seedlings shall be checked and supplemented in cloudy or light rainy days 25 days after planting;The seedlings shall be thinned 35 days after planting to remove the weak and keep the strong, and it is better to keep 1-2 healthy seedlings per plant.[1]
Water and fertilizer management
Cassava is relatively drought resistant, and the field water management should be based on the seedling situation and weather, and watering should be timely and appropriate.Avoid flooding, and drip irrigation is the best way to water.The soil should be kept wet or dry, and waterlogging should be drained in time in rainy season.Fertilization must be scientific and reasonable, focusing on organic fertilizer, and controlling the application amount of chemical fertilizer, especially nitrogen fertilizer.Promote the use of compost, compost and green manure, and prohibit the use of urban garbage fertilizer.Fertilization shall meet the requirements of NY/T394.Fertilization is divided into base fertilizer and topdressing twice.During land preparation, apply 15000 kg/hmtwoOrganic fertilizer as base fertilizer;One month after planting, apply 300kg/hm in rainy daystwoCompound fertilizer is used as topdressing.[1]
Control of diseases, pests and weeds
In China, cassava has few diseases, pests and weeds. The principle of prevention first and comprehensive prevention and control must be adopted for the prevention and control of diseases, pests and weeds. Priority should be given to agricultural prevention and control. The use of pesticides and mixtures prohibited by the state is prohibited.When pests and diseases do not occur in a large area, they should be manually pulled out and destroyed in time;Secondly, measures such as weeding and soil cultivation can be taken to create ecological conditions that are not conducive to the occurrence of diseases and pests, but are conducive to or not detrimental to the growth of cassava.If the area of diseases and pests is large, high efficiency, low toxicity and low residue pesticide varieties shall be selected for prevention and control.It is recommended to use manual, mechanical and cultivation techniques to control cassava grass damage, such as film mulching and weeding techniques, intercropping, fertilization and soil cultivation techniques, and intercropping.[1]
cassava
harvest
The edible cassava seed stem materials should be collected in time before the frost.The harvest period of edible cassava is generally from November to March of the next year, and the annual harvest can also be achieved through cultural technical measures.When harvesting root tubers, try not to damage root tubers to avoid affecting shelf life.[1]
Key values
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economic value
Cassava root tubers are rich in starch and are one of the raw materials of industrial starch.Cassava is widely cultivated and has a high yield. It is a common grain crop in the mountainous areas of southern China. Because the root tuber contains cyanate toxin, it can be eaten only after being bleached. Some low toxic varieties, such as bread cassava, can be detoxified after peeling off the cortex.[3]
Medical value
According to Xinhua Materia Medica, cassava can treat carbuncle, sore, blood stasis, pain, scabies, persistent ringworm and other symptoms. With the continuous in-depth study of bioactive ingredients in cassava roots, stems and leaves, people found that cassava has many health functions.[12]
Edible value
Cassava root tubers are rich in starch for food or paste, known as the "king of starch", and are the food rations of nearly 600 million people in the world;Stems and leaves can be used as fodder.[11]According to statistics, 65% of the world's total cassava production is used for human consumption. It is the main food source for low-income farmers in tropical wetlands and has high economic value.[12]
Current situation of cassava fresh food abroad
In foreign countries, the preparation method of cassava fresh food is relatively simple.Generally, the mature cassava is peeled and cooked by steaming, boiling, baking, baking and other general processing methods before being eaten directly, or the cassava is dried and mashed into cassava powder, and the cassava powder is fried to make steamed or cake food.Under the joint action of human wisdom and food civilization, different regions of the world have derived rich nutrition cassava fresh food.Indigenous people in Africa mash fresh cassava and use fermentation technology to make cassava wine drinks;Southeast Asian countries ferment the whole fresh cassava, cut it into small pieces and wrap it with banana leaves as snacks;Indonesia is dominated by cassava cakes;Brazilians use cassava flour, flour and glutinous rice flour to make baked goods.[4]
Fresh cassava in China
In the 1920s, cassava was introduced into China and planted in Guangxi, Guangdong, Hainan, Yunnan and other places.Before the 1950s, low yield edible sweet cassava was mainly used for food production in China.In the 1980s, China gradually solved the problem of food and clothing, and cassava was withdrawn from the diet of Chinese people, instead being used as feed and starch processing raw materials, and became an important starch and alcohol processing raw material in South China in the 1990s.After entering the 21st century, with the rapid economic development and the continuous improvement of people's living standards, cassava, as a nutritious and delicious coarse grain, has returned to the national table, giving full play to the positive role of optimizing the national diet structure, enriching diet culture and ensuring human health.[4]
Fresh cassava is not resistant to storage and needs to be eaten within 2 days after harvest. Usually, the peeled cassava is frozen or soaked in water to extend the preservation time.In order to reduce the adverse impact of the short storage time of cassava, Chinese food workers have developed a series of cassava fresh food based on the characteristics of cassava and their own dietary characteristics, mainly including cassava soup, cassava juice, cassava coconut cake, cassava chips, cassava dishes, cassava dumplings, cassava chips, etc.[4]
Steamed cassava
Variety classification
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Other species of Cassava are wild species, with many species and great morphological differences. There are nearly stemless subshrubs to small trees with stems 25 cm thick and 10-12 m high, and there are also grape growing species with special stems and leaves, which can be used for viewing. The number of chromosomes is 2n=36.The vast majority of wild species do not germinate when planted with cuttings, which makes it difficult to reproduce asexually with seed stems, but only with seeds. However, the germination rate of seeds is also very low, which is not as easy to reproduce as cultivated species.Wild species can also cross with each other, and their offspring can produce starch storage tubers, which has a wide range of adaptability, and can provide a variety of germplasm resources with disease resistance, low hydrocyanic acid content, high starch and high protein content for cross breeding.It is reported that the International Center for Tropical Agriculture has collected and preserved more than 100 wild cassava species, and 99 of them have been identified and evaluated, including manihot glauiviii, manihot melanobasis, manihot saxicola, and forked cassava
More than 20 wild species, such as Manihot dichotoma and Manihot aesculifolia, have been widely used in cassava disease resistance breeding and quality breeding.[14]
Taboos
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The "Compendium of Guangxi Ethnic Medicine" records the general manifestations of cassava poisoning: dizziness, nausea, vomiting, fatigue, sometimes abdominal pain, diarrhea, mouth saliva, severe spasticity, coma, mydriasis, and death due to respiratory paralysis after the onset. "Therefore, it is only for external use, not for internal use.[13]
Cassava is divided into bitter cassava and sweet cassava. The content of sweet cassava toxin is extremely low. The bitter cassava contains linseed bitter glycoside, which will produce a nerve poison under the action of gastric acid -Hydrocyanic acid。Sweet cassava needs to be peeled off, washed and boiled before eating.The bitter cassava must be detoxified before being cooked and eaten.Eating raw cassava or eating undercooked cassava, there will be a risk of poisoning.People say, 'Eating cassava will intoxicate people, but in fact it is slightly poisoned.[5]
The roots, stems and leaves of cassava contain toxic substances. If you eat raw or undercooked cassava or drink its soup, it can cause poisoning, and its toxins can cause nerve paralysis, or even permanent paralysis.[6]
Cassava flour sold formally on the market has undergone "detoxification" treatment.[5]
Cultivars
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Cultivated varieties: Manihot esculenta 'Variegata', with yellow and white stripes on its leaves.For viewing.[17]
