"Longevity food" sweet potato: what temperature is suitable for its growth? What cultivation and management techniques must be mastered to achieve high yields?

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

I. Functions 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 content 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. Beneficial to the heart

Sweet potato is rich in potassium, β-carotene, folic acid, vitamin C and vitamin B6, and all 5 of these components help prevent cardiovascular disease. Supplementing folic acid and vitamin B6 helps lower homocysteine levels in the blood; 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 best 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 clean out waste in the intestinal canal, gather toxins and waste together, and allow them to be smoothly excreted 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 the body's immunity, and prevent the occurrence of collagen disease. 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 sweet potato growth?

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

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

1. Cultivating strong seedlings

The high-yield 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, allowing the offspring to also maintain excellent traits.

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

2. Choosing soil

Sweet potato is not very strict about soil requirements, 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 tuberous roots are slender and neat, with bright skin color, good eating quality, high dry matter rate, and good storability.

However, the disadvantage is poor water and fertilizer retention capacity, 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 obtain high yields.

3. Timely planting

Sweet potato is a warmth-loving crop. The optimum temperature for tuberous root formation is 24-25°C, and the optimum temperature for tuberous 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 fully use the high-temperature and strong-light conditions of July-August, grow stems and leaves in time, branch early, form tubers early, and form many tubers.

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 tuber formation and early enlargement, and extend the effective enlargement period of the tubers so that sweet potato can achieve high yields.

4. Horizontal shallow planting with sufficient seedlings inserted

Sweet potato planting density and planting method also have a certain influence 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, 3800-4000 plants are inserted 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 ditch) and 36 cm high, with a plant spacing of 17 cm, plant horizontally and shallowly at 2-3 cm, water the planting holes in time and seal the soil. It is recommended to cut seedlings at noon on a sunny day and plant in the afternoon, trying to harvest seedlings and transplant on the same day to ensure the survival rate.

5. Rational fertilization and water

For autumn sweet potato, the principle of “light at the front, heavy in the middle, supplementary at the end” should be followed, mainly using organic fertilizer and supplementing with chemical fertilizer, applying frequently and lightly.