Geographical distribution of sweet potato
Sweet potato originated in South America and the big and small Antilles, and is widely cultivated in tropical and subtropical areas all over the world (mainly produced in 40? South), but it has also been successfully planted in some northern areas such as Heilongjiang Province. Widely cultivated in most parts of China.
Planting techniques of sweet potato
(1) Balanced Fertilization Ridge Cultivation According to the experiment, to produce 1 0,000 kilograms of potato chips, N 4-5 kilograms, P2O5O3-4-5 kilograms and K2O 7-8 kilograms need to be absorbed. Therefore, adequate fertilization and complete fertilizer preparation are important conditions for high yield of sweet potato. Fertilization should be carried out in the early stage of rapid fertilizer efficiency and early seedling development; The medium-term fertilizer efficiency is stable, strong but not prosperous; In the later stage, the fertilizer effect is long, and the plants are not premature. Generally, more than 4000kg organic fertilizer, urea 10kg, 20kg diammonium phosphate and 25kg potassium sulfate should be applied to high-yield fields. When ridging, the fertilization method should be strip application.
Sweet potato high-yield soil is characterized by loose structure, large porosity, good air permeability, sufficient oxygen supply and water permeability and drainage. Combining deep tillage with ridging cultivation can improve the physical and chemical properties of soil. The ridge protruding from the ground is not only beneficial to the drainage in rainy season, but also to the decomposition of organic matter, and it absorbs heat quickly during the day, increases the ground temperature, dissipates heat quickly at night, and has a large temperature difference between day and night, which is beneficial to the growth of sweet potatoes and the accumulation of nutrients in roots. When ridging, the ridge should be fat, the furrow should be narrow and deep, the ridge surface should be flat, the ridge soil should be solid, and there should be no big ridge and hard core. Ridge spacing is generally about 70cm.
(2) timely and early planting, and selecting strong seedling sweet potato tuber as vegetative body for asexual propagation. There is no obvious maturity. Generally, the growth stops when the temperature is lower than 15℃, and the tuber stops expanding when the local temperature drops to 16℃ ~ 18℃. Timely and early planting can prolong the growth period and form tuberous roots early, which can not only make the tuberous roots expand rapidly by using the temperature conditions before the rainy season, but also store the photosynthetic products formed by stems and leaves in the expanded tuberous roots in the high temperature and rainy season, thus promoting the coordinated growth of underground and aboveground parts. According to the meteorological data for many years, the planting time of spring potato in our city is around May 1. The experiment showed that the planting time on April 28th was 7 days longer than that on May 10, and the yield per mu was about 10%, with neat potato pieces and high quality of fresh potatoes.
In order to improve the survival rate, early growth and rapid growth of seedlings, the first batch of strong seedlings planted in seedbeds should be selected. The first batch of seedlings have stout stems, vigorous leaves and developed roots. Bile collection requires complete hardening of seedlings. Generally, seedlings are exposed to the sun for 3-5 days before planting, so that the leaves of seedlings are dark green and thick. For example, if you pinch off a quarter of the seedlings, white milk will flow out of the cross section. This kind of seedling has high survival rate, fast growth and high yield. Don't choose potato seedlings without hardening, black roots and burning buds.
(3) When the vines are lifted, topped and cored in time to enter the rainy season, the stems and leaves of sweet potato grow luxuriantly, the nodes are easy to breed, and the nutrients are scattered, which is not conducive to the transportation of photosynthetic products to root tubers. In order to prevent this phenomenon, vines were used in the past to reduce soil moisture, raise ground temperature and prevent the occurrence of node roots. According to the experiment, turning over the sweet potato seedlings is labor-consuming and reduces the yield, mainly because the stem and leaf are seriously damaged after turning over the seedlings, which breaks the optimal distribution of light energy received by the leaves, the photosynthetic intensity is reduced by 30%, the respiratory intensity is increased by 19%, and the yield is reduced by about 10%. In production, the vine was changed from vine to vine, which avoided the damage of stem and leaf and did not destroy the distribution of leaves, which was beneficial to high yield. But it shouldn't be too much, usually 1 ~ 2 times, and it will end before the end of August.
Topping and coring of sweet potato can control the length and growth of main stem, and promote the propagation and rapid branching of lateral buds. The specific method is to remove the growing point at the top of the main stem when the length of the main stem reaches 12 knots after sweet potato planting, so as to promote branching. When the branch grows to 12 knots, the growing point of the branch will be picked. This can coordinate the contradiction between the above-ground part and the underground part, which is beneficial to the expansion of the root tuber.
(4) Chemical control, flourishing control and clever fertilization of water. Too much fertilizer and water, especially too much N, will often lead to lush stems and leaves, affect the swelling of root tuber and reduce yield. Practice has proved that spraying plant growth inhibitors such as paclobutrazol or mepiquat chloride in potato fields can control the top and promote the bottom. Generally, spray it for the first time before the rainy season comes in early July, and then spray it every 10 ~ 15d for 3 ~ 4 times. Use 50 ~100g of paclobutrazol or 7 ~15g of mepiquat chloride per mu and spray 50 ~ 75kg of water evenly. When spraying, the dosage should be used flexibly according to the growth of stems and leaves, rainfall, variety characteristics and soil fertility.
On the basis of applying sufficient basic fertilizer, the top dressing of sweet potato is mainly irrigation and foliar spraying. The fertilizer mu for top dressing contains 4-5 kg of urea, 0/0 kg of calcium superphosphate leaching solution, 3 kg of potassium sulfate and 0/50-200 kg of water. When cracks begin to appear in the field, water trees along the cracks on cloudy or sunny afternoons, and require even topdressing. Foliar spraying depends on the growth of plants. N is the main fertilizer, with weak growth and signs of premature aging. Apply phosphorus and potassium fertilizer, add water 100kg, urea 0.5kg and potassium dihydrogen phosphate 0.2kg, and spray evenly. Phosphorus and potassium fertilizer are mainly sprayed, and 0.2% potassium dihydrogen phosphate aqueous solution can be sprayed. In late August, you can use a bag of sweet potato swelling agent per mu, add 20kg of water to dissolve and filter it, and then spray it evenly on the leaves of plants twice, with an interval of about 10d each time. In case of autumn drought, timely irrigation can prevent premature aging, prolong the functional period of leaves and increase the swelling speed of root tuber. Generally, the leaf area coefficient is 0.6 higher than that of irrigation in early September, and the yield per mu is 24.2%. Sweet potato is rich in water, and the irrigation amount should not be too large, 40m per mu? About. And be careful not to trample on the potato ridge after irrigation, so as not to affect the soil permeability.
In addition, in order to achieve high yield of sweet potato, it is necessary to cooperate with the selection of improved varieties, chemical weeding, pest control and other measures.
The value of sweet potato
economic value
Due to the development of food processing industry and fermentation industry, the industry with sweet potato as raw material has spread over more than ten industrial categories such as food, chemical industry, medical treatment and paper making, and there are more than 400 kinds of products with sweet potato as raw material. Sweet potato has high assimilation efficiency and is considered as an energy crop in Brazil and the Philippines. The alcohol produced by sweet potatoes can be used as a substitute for petroleum. Brazil has produced cars that use alcohol as fuel, and each ton of dried potatoes can produce 90 kilograms of alcohol. Our country has successfully tested that alcohol is added into gasoline at the ratio of 10%- 15%, and the existing engine can run normally without any modification. Preserved fruit syrup produced from dried potatoes can replace sucrose in cakes. The cake made of preserved fruit syrup is superior to sucrose in color, fragrance and taste, which can prevent food from drying and hardening. Adding candied sweet potato syrup to drinks can also avoid arteriosclerosis and obesity caused by eating sucrose. Citric acid in sweets and drinks is also made from dried potatoes. At present, the citric acid produced in China not only meets the domestic demand, but also is partially exported. Natural pigment made from sweet potato residue can be used for food coloring, which avoids the harm of synthetic pigment to human health. In the production of monosodium glutamate, dried potatoes can also be used as raw materials, and each ton of dried potatoes can produce monosodium glutamate 150? 200 Jin, not only saves a lot of wheat, but also reduces the cost.
5- Inositol fermented from dried potato is a high-grade condiment, which can improve the umami taste of food. Glycine made from sweet potato starch is 35 times sweeter than sucrose and can replace saccharin. Lysine can be extracted from dried potatoes, but it is lacking in general food. If 1% lysine is added to bread, the nutritional value can be increased by 30%, and adding lysine to animal feed can improve the feed value, shorten the feeding time and accelerate the growth rate. Tryptophan made from dried potatoes can be further converted into acetic acid. Spraying this hormone on fruit trees or vegetables can not only be used as fertilizer, but also stimulate plant growth and improve the quality of fruits and vegetables. Lactic acid produced by dried potato can be widely used in food, beverage, leather and other industrial sectors. The coated sugar acid extracted from dried potato is the basic raw material of synthetic fiber and can also improve the performance of coating. Phosphate starch can be synthesized from dried potato starch. It is a kind of adhesive, which is widely used in industry, and has the advantages of high viscosity, pure product, stable performance and difficult dehydration and shrinkage.
Starch fermentation can make Prussian blue, right? This white powder can be made into transparent film after treatment, which is odorless and nontoxic. Can be used for food packaging, and has the function of preventing food from spoilage. Cationic starch prepared from sweet potato starch can improve the physical properties of paper and enhance its tensile strength. Another chemical product of sweet potato starch is porous cyclodextrin, which can be used to package pesticides or cosmetics, so that drugs are not easy to lose or cosmetics can be preserved for a long time. Fresh potatoes have been successfully used as scale remover for industrial boilers. This descaling method is very popular because of its low cost and simple operation. With the continuous development of fermentation technology, chemical products with potato or starch as raw materials will change with each passing day, and new varieties and products will emerge one after another.
Therapeutic value
Sweet potato tuberous root is a convolvulaceae herb. Also known as flood, sweet potato, sweet potato, sweet potato, sweet potato, sweet potato, sweet potato, sweet potato and so on. The tuberous roots are white, yellow and lavender. It is cultivated all over China. Take it in winter, wash it, remove the fibrous roots and use it fresh, or slice it and dry it in the sun for later use.
[Attribute] Sweet in taste and flat in nature. It can invigorate the spleen, invigorate qi, moisten the intestines, relieve constipation, promote fluid production and quench thirst.
[Reference] Contains sugar, vitamin C, carotene (red skin and yellow heart potatoes contain more) and other ingredients.
【 Usage 】 Used for spleen deficiency and constipation; Lung and stomach fever, dry mouth.
[Usage] It is suitable for both raw and cooked, and there are various ways to eat it.
【 Note 】 The raw and cooked properties of this product are different, as mentioned above. Among potatoes, those white hearts are slightly lighter in taste, but the quality is crisp and juicy, and they are better eaten raw. Yellow or red hearts taste sweeter, but the quality is tight and the juice is slightly less, so cooked food is better.
? People who are full should not eat more, they will suffocate. ? (Compendium of Materia Medica) People with hyperacidity should not eat more. Eating more is acid reflux. People with spleen and stomach deficiency and cold should not eat raw food.
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1, brown sugar boiled sweet potato: 500g sweet potato, 60g brown sugar. Add some water to boil until cooked, eat potatoes and drink soup.
From The Golden Potato Biography. It says:? Those who suffer internal injuries due to drinking, are hot due to dampness, and are yellow due to heat, if they cook with this potato, their Huang Zi will return. ? This modification can also be used for the adjuvant treatment of jaundice (viral hepatitis).
2. Sweet potato powder honey cream: dry red potato chips 100g, ground into powder and mixed with water. Boil until the fire thickens, add 50g of honey and cook for one hour.
"Golden Potato Biography" said: If it is damp-heat dysentery, you can steam this potato, chew it with peony soup, or mix potato powder with winter honey to cure it. ? This method can be used for adjuvant treatment of dysentery.
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