Growth Environment and cultivation techniques of Sweet Potato

Growth Environment of Sweet Potato

(1) temperature. Sweet potato likes warm and cold. When planting seedlings, it takes 5 days for 15 ℃ to root, 17-18 ℃ for normal root, 20 ℃ for 3 days, and 27-30 ℃ for only one day.

The stem and leaf grow faster when the temperature is 25-28 ℃. When the temperature is more than 30 ℃, the stem and leaf grow faster, but the tuber expands slowly. The respiratory consumption was more than 38 ℃, and the stem and leaf grew slowly. The stem and leaf grew fast when the temperature was below 20 ℃, and stopped growing at 15 ℃. The duration below 10 ℃ became frost, and the stem and leaf withered.

The higher the soil temperature between 21 and 29 ℃, the faster the root formation and the more the number, but the tuber is smaller. The soil temperature of 22-24 ℃ is beneficial to the formation of root tubers. The soil temperature of 20-25 ℃ was the most suitable for root expansion, which was slower when it was lower than 20 ℃ or higher than 30 ℃, stopped expanding when it was lower than 18 ℃, was vulnerable to chilling injury when it was lower than 10 ℃, and froze at-2 ℃. During the period of root expansion, the larger temperature difference between day and night is beneficial to root expansion and nutrient accumulation.

(2) Lighting. Sweet potato likes light, under the condition of sufficient light, the leaf color is thicker, the leaf age is longer, the stem vine is sturdy, the stem transport tissue is developed, and the yield is higher. If the light is insufficient, the leaves are yellow, the leaves are more deciduous, the leaf age is short, the stem is slender, the transport tissue is underdeveloped, the organic nutrients formed by assimilation are less transported to the root tuber and the yield is low.

Being exposed to light for a long time every day is beneficial to the growth of stems and leaves, the stems become longer and the number of branches increase. It is more suitable for root expansion when exposed to light for 12.5-13 hours a day. Exposure to light for 8-9 hours a day is beneficial to budding and flowering, but not suitable for root expansion.

(3) moisture. Sweet potato is a drought-tolerant crop, but too much and too little moisture is not conducive to yield increase. Sweet potato is afraid of flooding, especially after fruiting, it has a great impact on the yield. The unbalanced growth rate of tuber inside and outside of the soil caused by the uncertainty of soil dryness and humidity often leads to the phenomenon of bark cracking. In short, sweet potatoes are afraid of both waterlogging and drought. The masses say, "dry long firewood roots, wet long whisker roots, non-dry and wet long roots." In order to obtain high yield of sweet potato, we should timely and properly irrigate according to specific conditions, drain waterlogging in time and thoroughly, and strengthen ploughing and preserving soil moisture in dry land.

(4) nutrients. Sweet potato has strong fertilizer absorption ability and tolerance to barren, but sufficient fertilizer must be applied in order to achieve high yield. In addition to nitrogen, phosphorus and potassium, sulfur, iron, magnesium and calcium also play an important role. Among the three elements, sweet potato has the most requirements for potassium, followed by nitrogen and phosphorus. According to the analysis, every 1000 jin of sweet potato contains 3.5jin of nitrogen, 1.75jin of phosphorus and 5.6jin of potassium. Therefore, increasing the application of potassium fertilizer, timely and appropriate amount of nitrogen and phosphorus fertilizer can significantly increase the yield.

(5) soil. It is better to use sandy loam and sandy soil with deep soil layer, rich organic matter, loose, aerated and good drainage performance. When the soil is sticky and heavy, the root skin color is not good, rough, the potato shape is irregular, the yield is low, and is not resistant to storage. However, sandy loam and sandy soil generally have low fertility and poor water retention, so fertilization and other measures should be adopted to gradually improve soil fertility in order to obtain high yield. Sweet potato is more resistant to acid and alkali, and the range of PH value is about 4.5-8.5, but 5.2-6.7 is suitable. When the soil salt content is more than 0.2%, it is not suitable to plant sweet potatoes.

Cultivation techniques of Sweet Potato

Seedling raising method

Sweet potato seedlings need to be raised 2 months before transplanting, that is, spring potato seedlings begin in late January, autumn potato seedlings in mid-late June, and early winter potato seedlings in the first and middle of August. One-time seedling can be used, or it can be propagated in stages.

Seed selection, seedling purification and rejuvenation are carried out every year. To select seeds in areas free of virus and scab, and in fields with the same varieties, select medium-sized seed potatoes with long, uniform, furrow-free, straight, smooth skin, without disease and insect spots and scars as seeds, soak 5~10min with 1.0% cupric sulfate solution or 2% sodium hydroxide solution before planting, or soak seed potatoes with biological agents allowed for organic production such as Bt and Beauveria bassiana for 2 hours, and it is best to propagate virus-free seedlings in a screen greenhouse.

Nursery bed base fertilizer should be fully applied, generally every 667m2 self-retting organic fertilizer 500~1000kg, mineral potassium and magnesium fertilizer 50kg. Disinfect the seedbed or the shed with stone-sulfur mixture or lime before planting.

Seedling stage management

During the seedling period, the sweet potato is fertilized timely according to the seedling condition, and the fertilizer is used with bio-organic fertilizer certified by organic or approved by the organic certification institution (NPK total nutrient content ≥ 6%, organic matter content ≥ 40%). The total amount of topdressing during the seedling period is generally 250kg per 667m2. In the first "red bud" stage, thin fertilizer and water are generally applied, and when the seedling height is 10~13cm, the second topdressing can be carried out. After each fertilization, the seedlings should be poured with clean water to prevent the fertilizer from adhering to the seedlings and causing the phenomenon of burning seedlings.

Soil cultivation can be divided into 2 to 3 times, seedling height 10cm, can be carried out for the first time, 7 days for the second time, co-culture soil 3~5cm. It is best to mix charred mud ash or rotten compost with fertile loose fine soil and sprinkle it evenly into the seedbed. Soil cultivation can be combined with the application of liquid fertilizer, so that the soil can be cultivated first and then fertilized, so that the soil and the base of the seedling can be closely combined to facilitate early and multiple new roots.

After seeding, Bt and other organic production permitted biological agents and 300x tea bran water were sprayed every 15 days, plant ash was sprinkled once, and sex hormone traps were put around the seedling bed or outside the seedling shed.