1. Growth conditions
The asexual reproduction process of potatoes starts from germination and goes through three growth stages: germination stage, seedling stage and tree development stage, and then enters the tuber forming stage and dormancy. period to complete a reproductive cycle. After a period of dormancy, the harvested tubers can germinate at 4°C, and the buds grow fastest at 13°C. The optimal temperature for the growth of stems and leaves is 21°C; the optimal temperature during the tuber formation period is 14-24°C during the day and 12-17°C at night. Short days and strong light are conducive to the expansion of tubers, and excessive temperatures will cause smaller tubers. Potatoes should be planted in fertile and loose sandy soil or loam with good drainage, deep tillage, high organic matter content. Soil pH 5.0 to 6.5 is more suitable.
2. Characteristics of fertilizer requirements
Nitrogen enables the stems and leaves to grow luxuriantly, the leaves are dark green, photosynthesis is strong, the accumulation of organic matter is increased, and the protein content is increased. If there is too much nitrogen fertilizer, especially in the later stages of growth, it will promote leggy plants and tender tissues, delay tuber maturity, and reduce yields. Phosphorus promotes plant growth and robustness, improves tuber quality and storability, and increases starch content and yield. If there is insufficient phosphorus, the plants and leaves will be dwarfed, photosynthesis will be weakened, and yield will be reduced. Potato tubers will be prone to hollowness, rust spots, hardening, and difficulty in cooking, which will affect the food quality. Potassium can improve plant disease resistance and cold tolerance, accelerate nutrient transport, and increase starch and vitamin content in tubers. If potassium is insufficient, the growth will be inhibited, the above-ground parts will be dwarfed, the internodes will be shortened, the plants will be dense, the leaves will be small and dark green and gradually turn to bronze, the leaf edges will turn brown and die, the potato pieces will mostly be elongated or spindle-shaped, and the edible part Grayish black.
Boron helps potato tubers grow larger and prevents cracking. It has a special effect on improving the net photosynthetic productivity of plants. Copper can increase protein content and increase plant respiration. It has good effects on increasing chlorophyll content, delaying leaf senescence and enhancing drought resistance. It also has the effect of increasing the net photosynthetic productivity of plants.
Potatoes absorb the most potassium fertilizer during the growth period, followed by nitrogen fertilizer and the least phosphorus fertilizer. Nitrogen is most abundant from the time of germination to the time of flower bud growth. The phosphorus content decreases with the extension of the plant growth period. The potassium content is low during germination, increases rapidly after germination, and then decreases after the flowering stage. Both magnesium and calcium tend to increase with the extension of the growth period. Nutrients from the stems and leaves move into the tubers as they begin to enlarge. The inorganic components nitrogen and potassium in tubers account for 70% of the total absorption, phosphorus accounts for 90%, calcium accounts for 10%, and magnesium accounts for about 50%.
3. Fertilization technology
Base fertilizer
Mainly organic fertilizer, the general dosage is 22.5 to 45 tons per hectare. The application method depends on the amount and quality of organic fertilizer. A small amount (15 tons per hectare) of high-quality organic fertilizer can be applied along the sowing furrow or in a hole on the seed potato blocks, and then covered with soil. When the amount of coarse fertilizer is large, it should be spread and then plowed into the soil. Phosphorus and potassium fertilizers should also be used as base fertilizers.
Seed fertilizer
Apply when sowing potato tubers. Use superphosphate or a small amount of nitrogen fertilizer as seed fertilizer. However, it should be noted that nitrogen and phosphorus fertilizers cannot directly contact the seed potatoes. In many areas, there is a habit of sowing seed potatoes dipped in plant ash. The plant ash not only plays a role in disease prevention, but also acts as a seed fertilizer.
Top dressing
Mostly nitrogen fertilizers are used, and the dosage varies depending on soil fertility, previous crops, irrigation, density and phosphorus fertilizer application levels. When dry farming without the application of organic fertilizers, the effect of nitrogen fertilizer as top dressing is poor, and it is better to use it as base fertilizer. The nitrogen application rate is generally 60kg nitrogen per hectare. If watering can be done once during the budding period, increase it to 90kg of nitrogen, and apply it deeply before watering. For potatoes planted after sugar beet and sorghum, the amount of nitrogen fertilizer should be appropriately increased to 105kg nitrogen per hectare; when the density increases or phosphate fertilizer is applied, the amount of nitrogen fertilizer should be increased to 135kg nitrogen per hectare. In short, the nitrogen fertilizer for potatoes is to apply 60 to 135kg of nitrogen per hectare according to the conditions, and it is applied before the potatoes bloom. After flowering, nitrogen fertilizer is generally no longer applied. In the later stage, in order to prevent premature aging, 0.5 urea solution and 0.2 potassium dihydrogen phosphate solution can be sprayed as extra-root top dressing according to the growth conditions of the plants.
4. Fertilization standards
For every 1,000kg of potatoes produced, 4.4 to 5.5kg of nitrogen, 1.8 to 2.2kg of phosphorus pentoxide, and 7.9 to 10.2kg of potassium oxide are required. The ratio of the three is 1:0.4:2. Potatoes are a typical potassium-loving crop.