What temperature is suitable for growing sweet potato, the "longevity food"? Which cultivation and management techniques must be mastered to achieve high yields?

Sweet potato is also known as yam, red yam, sweet potato, fan shu, fan yu, and di gua (in the north). It is rich in protein, starch, pectin, cellulose, amino acids, vitamins and various minerals, and has earned the reputation of a "longevity food". Today, China ranks first in the world in both sweet potato planting area and total output. What temperature is suitable for growing sweet potato? Which cultivation and management techniques must be mastered to achieve high yields?

I. Benefits and effects of sweet potato

1. Anti-cancer effect

The nutrients with the strongest anti-cancer effects in the diet are β-carotene (a precursor of vitamin A), vitamin C and folic acid, which help maintain normal folic acid levels in the human body, while too low a folic acid level in the body increases the risk of cancer. The high content of dietary fiber in sweet potato promotes gastrointestinal motility and helps prevent constipation and colorectal cancer.

2. Good for the heart

Sweet potato is rich in potassium, β-carotene, folic acid, vitamin C and vitamin B6. All five of these components help prevent cardiovascular disease. Supplementing folic acid and vitamin B6 helps lower blood homocysteine levels; the latter can damage arterial blood vessels and is an independent risk factor for cardiovascular disease.

3. Preventing emphysema

Sweet potato is rich in vitamin A. American researchers suggest that smokers or those exposed to secondhand smoke should eat some vitamin A-rich foods such as sweet potato every day to prevent emphysema.

4. Weight loss and slimming

Sweet potato is rich in dietary fiber. After entering the intestinal tract, it can clear waste from the intestinal canal, gather toxins and waste together, and help them be discharged smoothly from the body. Sweet potato can also create new cells in the intestines and promote metabolism.

5. Enhancing immune function

Sweet potato contains a large amount of mucin, which can prevent atrophy of the connective tissue of the liver and kidneys, improve body immunity, and prevent the occurrence of collagen diseases. Sweet potato also contains calcium and magnesium, which can prevent osteoporosis.

6. Sweet potato can also inhibit skin aging, maintain skin elasticity, and slow down the body's aging process.

II. What temperature is suitable for growing sweet potato?

Sweet potato likes warmth and fears cold. At 17-18°C rooting is normal, at 20°C roots form in 3 days, and at 27-30°C roots can form in just one day; at an air temperature of 25-28°C stems and leaves grow quickly; a soil temperature of 22-24°C is more favorable for the formation of storage roots.

III. High-yield cultivation and management techniques for sweet potato

1. Cultivating strong seedlings

The high-yielding performance of sweet potato varieties and the quality of the potato seedlings are the internal factors determining yield. Virus-free, disease-free strong seedlings can pass on excellent genes so that the offspring also retain excellent traits.

When planting, choose virus-free, robust potato seedlings as much as possible. Therefore, doing a good job of raising seedlings from storage roots, improving seedling quality, and purifying and rejuvenating variety characteristics can significantly increase sweet potato yield.

2. Choosing soil

Sweet potato is not very demanding about soil, but it prefers light loam or sandy loam with deep, loose soil, good drainage, rich organic matter, and good fertility conditions. This type of soil is loose and breathable, and the storage roots are slender and uniform, with bright skin color, good eating quality, high dry matter yield, and good storability.

But the disadvantage is poor water and fertilizer retention, making it prone to drought and fertilizer deficiency. Field management measures such as increased fertilization and irrigation (drip irrigation with water and fertilizer, foliar fertilization, etc.) are needed to achieve high yields.

3. Timely planting

Sweet potato is a warmth-loving crop. The optimum temperature for storage root formation is 24-25°C, and the optimum temperature for storage root enlargement is 22-24°C. According to the conditions required for sweet potato growth and the local climate characteristics, seize the season and plant around "Dashu" (Major Heat), so that in the early stage the sweet potato can make full use of the high temperature and strong light conditions of July-August, grow stems and leaves in time, branch early, form storage roots early, and form many storage roots.

January is the month with the lowest temperatures, which is unfavorable for sweet potato growth and development and may even cause freezing damage. Therefore, it is necessary to master timely early planting, strive for early storage root formation and early enlargement, and extend the effective enlargement period of the storage roots, so as to achieve high sweet potato yields.

4. Horizontal shallow planting with sufficient seedlings

Sweet potato planting density and planting method also have a certain impact on yield. It should not be too sparse, nor too dense. If too dense, photosynthesis will be affected and the plants will not grow well; if too sparse, it not only wastes soil but also easily breeds weeds, diseases and insect pests, affecting sweet potato growth.

Generally, plant 3800-4000 plants per mu, using the method of single-row planting on high, narrow ridges with horizontal shallow planting. Build trapezoidal ridges 90 cm wide (including the trench) and 36 cm high, with a plant spacing of 17 cm, plant horizontally and shallowly at 2-3 cm, water the holes promptly and cover with soil. It is recommended to cut seedlings at noon on a sunny day and plant in the afternoon, trying to collect seedlings the same day and transplant them the same day to ensure the survival rate.

5. Rational fertilization and watering

For autumn sweet potato, follow the principle of "light at the front, heavy in the middle, supplementary at the back", mainly using organic fertilizer, supplemented by chemical fertilizer, and apply frequently in small amounts.