Purple Potato Planting Technique

Purple sweet potato likes warm climate environment. The suitable temperature for stem and leaf growth is 18~25℃, and it stops growing when the temperature is lower than 15℃. The optimum ground temperature for root tuber growth was 22~24℃, and the root tuber stopped expanding when the ground temperature was lower than 20℃. Purple sweet potato is a short-day crop, which needs sufficient light and high intensity. The suitable soil moisture content for purple sweet potato growing period is 60%~80% of the maximum field moisture content.

variety selection

Purple sweet potato can be divided into fresh food type and processing type according to its use. When selecting seeds, it is selected according to the specific purpose of cultivation. For fresh food type, select varieties with good taste, moderate pigment content, good disease resistance and beautiful potato shape, and for processing type, select varieties with high pigment, good disease resistance and high dry rate.

seedling technology

Early breeding, full cultivation and strong mu, forming early and strong adventitious roots are the basis for rapid seedling survival, early and many tubers and high yield. In order to prevent the occurrence of purple sweet potato black spot and other diseases, strict control should be taken before seedling raising. Potato pieces without scars and spots should be selected as seed potatoes. 70% methyl thiophane 1000 times solution at 51-54℃ or 25% carbendazim 500 times solution can be used for soaking seeds for about 5 minutes.

1. Prepare seedbed

Seedling in general in March, late sunny days, choose leeward sunny, dry terrain, soil permeability is good, rich in organic matter, convenient management of sandy soil or sandy loam do seedbed. Seedbed width 1.2 m, depth 20~30cm, depending on the length of the garden. 10 ~15 loads of decomposed human excrement are applied per mu, and potatoes are discharged after being absorbed and dried by soil.

2. Arrange seed potatoes

When the temperature reaches about 15 degrees, purple sweet potato seeds are discharged on the seedbed, generally about 18kg of seed potatoes are used per square meter, the back is upward, the head is slightly higher, the tail is muddy, the head and tail direction are consistent, and then 10 ~15 loads of decomposed fertilizer are used per mu, evenly covered on the seed potatoes, covered with 1.5-2cm fine soil, then covered with plastic film, and compacted with fine soil around.

3. Seedbed management

Seedbed management mainly pay attention to heat preservation, moisture, ventilation and other measures to temperature-based. Before emergence, cover the straw curtain at night and keep the bed temperature at 25-35℃. After emergence, the temperature should be controlled at 20-25℃ to prevent high temperature burning seedlings. If the temperature in the film exceeds 30℃, ventilation and heat dissipation should be carried out in time to prevent burning seedlings. Keep warm when cold wave comes. Seed potatoes are generally not watered before emergence to facilitate high temperature germination, disease prevention and emergence. If the seedbed is too dry, spray water on the seedbed with a sprayer. After emergence should pay attention to seedbed humidity, when the seedbed white to timely watering, wetting the bed soil and watering dilute human excrement, in order to promote the growth of potato seedlings. Fertilization is required after seed potatoes germinate. The first "red bud" period, generally thin human excrement is good; when the seedling height of 10-13 cm, the second topdressing can be carried out, with human excrement or urea topdressing. After each fertilization, the seedlings should be washed with clean water to prevent the fertilizer from adhering to the seedlings and causing the phenomenon of burning. Cultivation can be divided into 2-3 times, seedling height of about 10 cm, can be carried out for the first time, every week for the second time, a total of 3-5 cm. Cultivate soil best with fertile loose fine soil mixed coke mud or decomposed compost, evenly scattered into the seedbed. Cultivation can be combined with liquid fertilizer application, so that soil and seedling base are closely combined to facilitate early development and multiple new roots.

land preparation and ridging

1. Soil treatment

Purple sweet potato has wide adaptability to soil. To achieve high yield, it is appropriate to choose sandy soil with loose and fertile land and high organic matter. Because purple sweet potato root elongation is strong, root tuber expansion needs deep loose land, in order to obtain high yield, it is necessary to deeply plow and harrow after thawing in spring to preserve soil moisture, pick clean root stubble before transplanting, break broken seeds, combine fertilization and pest control (soil treatment), ridge once. Every 667㎡, 0.25-0.5kg of 47% Lesben is mixed into 1000 times solution and sprayed on the ground and then deeply turned to prevent underground pests.

2. Deep ploughing

Sweet potato has flat planting and ridge planting two ways, and ridge planting is the best. The advantages of ridge planting are: thickening soil layer, expanding root activity range, loosening soil, expanding surface soil contact area with air and sunlight, facilitating gas exchange and increasing soil temperature, increasing temperature difference between day and night, and facilitating irrigation. Ridging should be carried out in sunny days when the soil is moderately dry and wet. Deep and large ridges are better, so as to achieve deep ploughing, fine soil and straight ridges for drainage and irrigation. The ridge surface should be flat and smooth, so as to facilitate the cultivation of seedlings. The size of ridges should be determined according to local conditions such as field type, soil quality, planting season, planting mode, growth period and variety. Clay with strong water retention capacity should have high ridges and narrow ridges; sandy soil with poor water retention capacity should have wide ridges and slightly short ridges. Ridging methods include single row (ridge spacing 60-70cm with furrow, plant spacing 20-25cm), single row double row (ridge spacing 120cm with furrow, plant spacing 25-30cm), etc.

plastic film mulching cultivation

1. The yield of purple sweet potato was positively correlated with its growth period. The longer the growth period, the higher the yield. Cultivation methods mainly include conventional, no-tillage and plastic film mulching cultivation in paddy field. Early transplanting and plastic film mulching were beneficial to increase yield, starch content and quality of fresh potato. Cutting density is one of the main factors determining the number of tubers per mu. In a certain range, with the increase of density, the number of tubers per mu increases, and the yield increases accordingly. According to experiments, the yield per mu reaches 1500 kg, the fresh weight of single tuber is kept below 200 g, and the cutting density is 4000-5000 plants/mu. The planting method can adopt narrow ridge and single row, namely row spacing of 50-60 cm and plant spacing of 25-30 cm, or double ridge and double row, namely ridge width of 1-1.2 m, cutting of 2 rows per ridge and plant spacing of 30-35 cm. The cutting method is shallow oblique cutting, early tuber setting, tuber setting more, tuber size uniform, high yield, good commodity.

2. Plastic film mulching cultivation

Mulch cultivation has the following advantages:

① Temperature preservation: After the purple sweet potato field is covered with plastic film, the soil can better absorb and preserve solar radiation energy, and the ground is heated quickly by light, and the ground temperature is lost slowly, which plays a role in heat preservation. It is reported that the plastic film mulching cultivation of sweet potato increased the accumulated temperature of soil by 460℃ compared with the control (no plastic film mulching) in the whole growth period.

② Adjust soil moisture: Due to the barrier of plastic film, it can reduce the evaporation of soil moisture, especially in areas with heavy spring drought, and the effect of moisture preservation is more ideal. In rainy season, plastic film plots are easy to drain and not easy to produce waterlogging. In case of late drought, plastic film can play a role in moisture conservation.

③ Increase nutrient accumulation: After mulching, soil temperature rises, temperature increases, microorganisms are unusually active, promote the decomposition of organic matter and potential humus, and accelerate the accumulation and transformation of nutrients.

④ Improve the physical properties of the soil: the surface of the covered soil is not affected by rain, so the soil is always loose, which is beneficial to the growth of roots in the early stage and to the expansion of potato in the later stage.

5. Prevention and control of diseases and grass hazards: sweet potato nematode disease is a destructive disease in sweet potato production. At present, the control effect of chemicals is not ideal, and solar radiation energy can be used after covering the film to increase the soil temperature and kill nematodes. The disease prevention effect is good and does not pollute the environment. At the same time, the high temperature under the film can scald weeds, reduce weeding labor, and avoid weeds and sweet potatoes competing for fertilizer, water and space.

Promote the development of sweet potato roots, stems and leaves: film mulching roots 4-6 days earlier than open cultivation of sweet potato, roots grow faster, strong roots can absorb more nutrients from the soil, for the healthy growth of plants and potato formation, expansion laid the foundation. The branch number, leaf number, stem length and fresh weight of sweet potato under plastic film mulching were increased by more than 50% compared with those under open field cultivation.

(7) Significant yield increase and quality improvement: sweet potato seedlings grow faster after mulching, summer sweet potato seedlings are cut and sold, and the cost of mulching film can be recovered. The average yield per plant was 0.7 kg more than CK, the total yield was increased by 32.6%, and the ratio of big tuber and starch content were increased. The soil of plastic film mulching cultivation is loose and easy to harvest, which reduces the harvest damage rate and improves the harvest quality.

3. Planting seedling cover film

There are two ways to cover the film, one is to cover the film after cutting potato seedlings. Its advantage is easy to operate. Fast speed, suitable for large-area planting; the method is to first put seedlings into the hole, where conditions can be watered hole by hole, water volume should be large, after water infiltration slightly dry, bury soil compaction, and keep the ridge surface flat, while the seedlings are soft when the film is covered, so as to avoid the phenomenon that the seedlings are easy to break with the film. After covering the film, cut a T-shaped mouth at the seedling with a knife, pin the seedling out with your fingers, and then seal the mouth with wet soil. After the film should be checked frequently, found that the film was blown up by the wind or film surface damage, should be timely covered with soil seal; disadvantage is that it is not easy to maintain the original ridge after planting, need to re-level ridge surface, cover film can be tight. Another method is to plant seedlings after film mulching, its advantage is that it can be used for early ridge and early film mulching, which is conducive to moisturizing and warming. Cuttage seedlings when the temperature is higher conducive to slow seedlings, survival. No digging is needed during cuttage. When planting seedlings, soil furrows with a length of 5 - 7 cm and a depth of 5 cm are drawn on the film ridge surface, and potato seedlings are inserted into the furrows. The film breaking, digging and seedling planting are completed at one time.

4. Fertilization

According to the principle of "mainly organic fertilizer, supplemented by chemical fertilizer; mainly basal fertilizer, supplemented by topdressing", sweet potato has a long growth period, strong absorption fertility and large fertilizer requirement. K fertilizer was the most, N fertilizer was the second, P fertilizer was the least. For each 500 kg fresh potato production, the amount of fertilizer applied is about 2.5 kg N, 2.5 kg P, 3.1 kg K, and the ratio of N:P:K is 1:1:2. Fertilization is based on basal fertilizer, which generally accounts for about 70% of the total fertilizer application. Generally, the yield of fresh potato per mu is 2500-3500 kg, and it is required to apply 1500-2000 kg organic fertilizer plus 40-50 kg compound fertilizer for flue-cured tobacco per mu, or 1500-2000 kg organic fertilizer plus 10-12 kg urea, 12-15 kg potassium sulfate and 20-25 kg calcium superphosphate per mu. The yield per mu is 1500-2000 kg, which requires 750-1250 kg organic fertilizer plus 30-40 kg high-quality potassium sulfate compound fertilizer per mu, or 750-1250 kg organic fertilizer plus 5-8 kg urea, 10 kg potassium sulfate and 15 kg calcium superphosphate per mu. Base fertilizer is applied by ridge-breaking and striping.

field management

1. Early management

The key point is to check seedlings and supplement seedlings, prevent lack of plants and broken ridges, timely use large seedlings and large vines to supplement planting, and ensure density. 10~15 days after cuttage for the first time, combined with topdressing. In the fertile water condition is better, the growing prosperous plot will be potato seedling top, in order to promote the stem base branch, in order to more tubers, big tubers. This variety needs a lot of fertilizer. About 30 days after cutting, 5-7kg compound fertilizer is applied per mu in combination with ridge breaking and whitening for poor soil fertility plots.

2. Medium-term management

① Pay attention to weeding: In the middle and late stages, the growth of grass is generally inhibited, and the main harm is high-stem weeds, which should be removed in time. Too many weeds not only compete with sweet potato for nutrients, shade affects photosynthesis of sweet potato, ventilation between vines is poor, respiration is intensified, nutrient accumulation is less, yield is seriously reduced, and weeds affect harvesting mechanization.

② Generally do not turn the vine: turning the vine will seriously disrupt the growth order of sweet potato, and it is easy to break the vine in the process of turning, which is easy to cause yield reduction. At the same time, it also consumes a lot of man-hours and increases the cost of planting. General individual vine grounding root will not affect the yield, the appropriate tendril can be raised.

③ Proper control of growth: vine growth in the middle and late stages has been formed. If it is too vigorous, it will affect the transfer of nutrients to the underground part, and then affect the yield of root tuber. At this time, it is difficult to control it. Regulators such as mepiquat amine can be sprayed appropriately, but it will not play a fundamental role. The ideal vine structure is mostly erect or semi-erect branches, minimizing the proportion of grounded vines, increasing canopy height, ensuring good ventilation, and seeing 5% of the ground from above.

④ Reasonable topdressing: If the vine grows slowly, you can see more than 10% of the ground, the vine is short, the leaves are small, and the roots can be diluted with compound fertilizer 40-60 days before harvest. The fertilizer dosage is equivalent to 3-5 kg of diammonium phosphate and 2 kg of potassium sulfate per mu. Pay attention to the dilution multiple to prevent root burning. In case of excessive growth of stems and leaves, 15% paclobutrazol can be sprayed to control excessive growth of aboveground parts and facilitate potato expansion. Clever application of crack fertilizer can promote potato swelling. Generally, crack fertilizer is applied when the ridge surface is cracked, mainly nitrogen and potassium fertilizer, and the dosage per mu is 5 kg of urea and 10 kg of potassium sulfate. Apply topdressing at different stages, sowing after rain, the amount of application should be based on soil, basal fertilizer and stem growth, respectively in seedling stage, stem and leaf flourishing stage, potato block expansion stage with urea and potassium fertilizer application

5. Pay attention to pulling out diseased plants: In recent years, sweet potato diseases spread rapidly, resulting in serious yield reduction. In the middle stage, attention should be paid to pulling out plants with obvious symptoms, such as cracking of stem base, yellowing of plants, abnormal color of leaves, shrinkage of vines, etc., so as to reduce the risk of disease transmission.

3. Post-management

The key point is to look at the seedlings and apply root tracing to prevent premature aging. Purple sweet potato in the middle and late period if continuous rain, stem and leaf flourishing, should be used to lift the vine method. Break off the adventitious roots that occur on the stem nodes to control the growth of the aboveground part and facilitate the expansion of the root tuber. Do not use the method of turning vines to artificially cause unnecessary yield reduction and appropriately delay harvest.

pest control

1. Potato black rot: It is harmful to sweet potato seedling, field growth and storage period. The disease spots mostly occur on the wound, showing black to brown, circular or irregular shape, and the center is slightly concave. Sick potatoes become bitter and inedible. Generally use 50% carbendazim wettable powder 1000 times soaking for 10 minutes, also available 50% carbendazim 500-700 soaking seedlings for 2-3 minutes, the effect is good.

2. Soft rot: It mainly occurs on potato pieces during storage period. Soft rot bacteria first invade the internal development from the wound, destroy the intermediate layer of cells, present soft rot, watery, farmers call it "water rot", and the affected potato meat presents yellowish white and emits aromatic wine. Control method can be used 50%-70% thiophanate-methyl WP 500-700 times soaking potato 1-2 times, the effect is good.

3. Sweet potato root rot: also known as sweet potato root rot disease, the root system is infected to form black-brown spots, which then turn black and rot, the leaves are wilted, withered and shed, the potato pieces are infected, brown to black-brown spots form abnormal potatoes, and the control method can be sprayed twice with 50% thiophanate-methyl wettable powder 700-1000 times, with good effect.

4. Sweet potato weevil A: It is one of the important quarantine objects. The adults nibble on the bud, stem and petiole cortex of sweet potato and bite the root tuber to form small holes. When it is serious, the yield will be affected. Control methods: In the early stage, the potato head can be watered with water mixed with agricultural music, or the mixture of 600 times trichlorfon and kung fu can be sprayed on the potato and purple sweet potato varieties.

Purple sweet potato has dozens of varieties, after screening, there are suitable for fresh food, there are suitable for processing, there are suitable for extracting purple pigment, according to different varieties have summarized a complete set of cultivation techniques. In my opinion, farmers planting purple sweet potato should first recognize the market and choose the right variety. If as food must sell good, smooth skin, uniform size, market time earlier than ordinary varieties, appropriate control of purple sweet potato weight, so that the market will be good; such as purple sweet potato is used to extract purple pigment, it is necessary to plant purple high purity; do wine, choose some old varieties with high yield.

Harvest and storage

Purple sweet potato planting requirements in mid-October, late harvest, fresh type purple sweet potato delayed to early November, must be harvested before frost.

Before storage, the potato cellar should be cleaned, topsoil removed and disinfected; purple sweet potatoes should be sunned for 1-2 days before entering the cellar to heal wounds; during storage, ventilation and humidity should be paid attention to in the early stage, and heat preservation and moisture should be paid in the later stage.