Potato in various growth periods of encounter of soil water supply and accompanied by a sudden change of temperature, as in low temperature conditions of drought and rainfall short time interleaved; drought and rainfall and high temperature and cold alternately; alternating drought and rainfall in the condition of high temperature; caused by tuber deformities growth, thus affecting the commodity quality of tubers.

4 soil on soil requirements are not very strict requirements of potato, slightly acidic soil, with pH 5.5 ~ 6.5 is the most suitable. But in the north of the slightly alkaline soil can also grow well, generally in the range of pH 5 ~ 8 can be good growth. Potato salt tolerance ability is poor, when the soil salinity reached 0.01%, plant performance sensitive, tuber yield increased with the increase of chloride content in the soil and decreased, therefore, saline alkali land can not use potassium chloride.
To obtain high yield, with rich soil, deep soil, loose structure, good drainage and ventilation and rich sandy loam or loam is the most suitable. The soil with such structure has good water and fertilizer conservation, which is good for the root development of potato and the enlargement of tuber. Potato Planted in the soil, the emergence of fast, tubers formed early, potato tuber neat, potato skin smooth, tuber flesh color, yield and starch content were higher. Due to the deep soil, loose soil, rain for a long time can be timely infiltration or exclusion, conducive to the harvest of potato tubers, reducing the rate of decay of the tuber.
Although the weight of the soil is strong, the soil moisture is poor and the air permeability is poor. When seeding, such as low temperature and high humidity, the potato in the soil can not be timely emergence, decay caused by seed. After seedling emergence, the root is often poor, which can affect the normal growth of the plant and the expansion of the tuber. At the seedling stage but also prone to black shank. Harvest, such as soil water too much and not timely discharge, a lack of oxygen in the soil, increasing tuber lenticels, exposed cells, highly susceptible to bacterial diseases, leading to decay. Viscosity of planting potato in the heavy soil, high ridge, the seed planting in the middle part of the ridge in the ridge and furrow, to reduce the permeability of soil poor or poor drainage leads to bad. In terms of field management, to master the appropriate moisture, cultivating, weeding and ridging; soil moisture multitemporal, soil is sticky, not field operation; less water, the soil becomes dry and hard, cultivation and difficulties, and easy to produce big clod. Clay soil can through the sand mixing was improved, as long as good drainage, drought can timely irrigation, seasonable intertill, also can obtain high yield.
The soil structure of sandy soil is poor, the amount of water evaporation is big, and the ability of keeping water and fertilizer is poor, so the organic fertilizer should be applied to improve the structure of sand. Potato planting, fast rise of soil temperature in spring, can early sowing in good time; planting potato in the sand, conducive to the cultivation operations and harvest, even if the rainfall, storm, can be carried out cultivation or harvest and tuber rot rate is low. The tuber of the tuber is smooth and bright, the potato is regular, the starch content is relatively high, and the product is good.
5 nutrition the production of vegetative potato is formed by absorbing the mineral, water and assimilation of carbon dioxide, and promoting the development of plant and all other life activities. In the cultivation process, only to ensure that the plant growth and development of the necessary nutrients, in order to obtain the tuber yield and quality.
More than ten kinds of nutritional elements, namely, carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, boron, zinc, manganese, copper, molybdenum, sodium and so on. In addition to carbon, hydrogen, oxygen is through the leaf photosynthesis, from the atmosphere and water have to come, the other nutrient elements are mainly absorbed through the roots from the soil. Among soil absorption pathway is required for the maximum amount of nitrogen, phosphorus and potassium (known for a large number of elements), followed by a small amount of calcium, magnesium, sulfur (volume elements) and small amounts of iron, boron, zinc, manganese, copper, molybdenum and sodium (trace elements). Mineral elements in the composition of potato production of dry matter accounted for only about 5%, the vast majority of dry matter is composed of carbohydrates produced by photosynthesis. But minerals, through increasing the photosynthetic rate, participate in and promote the synthesis, translocation and distribution of photosynthetic products, and thus play an important role in the formation of yield. In the process of potato growth and development, if any of these elements, will cause plant growth and development disorders, and ultimately lead to production and reduce quality.
The absorption law of nitrogen and potassium during the growth period of potato was basically similar. Seedling plants small, need less fertilizer, absorption rate is slower; tuber form stage and tuber growth period, due to strong growth and tuber formation and rapid enlargement of stem and leaf, nutrient requirement increase sharply, is potato life of nitrogen and potassium uptake rate the fastest, absorbed the largest number of times; tuber growth of late to starch accumulation period, slowed down the speed of nutrient absorption, absorption quantity is also reduced. The absorption and utilization of phosphorus during the growth period of potato were different from the absorption and utilization of nitrogen and potassium. During the seedling stage, the absorption and utilization were less, and the absorption intensity increased rapidly during the tuber formation stage, and the absorption intensity of the starch accumulation period was higher than that of the starch accumulation stage. The accumulation of nitrogen, phosphorus and potassium in potato increased with the increase of dry matter accumulation, and reached the maximum value at the starch accumulation stage.
Potato absorption of calcium, magnesium, sulfur, seedling stage rarely, absorption rate slowly; tuber formation stage absorption increases sharply, until the tuber growth of late and slow down. Calcium, magnesium and sulfur are mainly used in root, stem and leaf of root, stem and leaf in each growth period. During the whole growth period and concentration of calcium and magnesium ions in roots, stems and leaves tend to increase, which is mainly for transporting system restriction of calcium, magnesium operations sake. Potatoes absorb trace elements very little, should be based on the rational use of the content of the soil, to achieve a better effect of increasing production.
For the potato crop, the maximum amount of potassium is required in the three element of the fertilizer. Potato production of 500 kg tubers, the need to absorb nitrogen from the soil 2.5 ~ 3 kg, phosphorus 0.5 ~ 1.5 kg, potassium 6 ~ 6.5 kg. In the three major elements of nitrogen, phosphorus and potassium, nitrogen fertilizer on potato growth has an important role in nitrogen is part of the crop in many important organic compounds, such as protein, chlorophyll, alkaloids and some endogenous hormones contain nitrogen. Sufficient nitrogen nutrition can promote the growth of potato stems and leaves, lush foliage, color Nonglv, large area of assimilation, prolong the function period of leaves, strong photosynthesis, net photosynthetic production rate increased, the beneficial nutrient accumulation. Application of nitrogen in excess, caused the plants to the leggy, stems and leaves of mutual shading, photosynthetic efficiency and reduce, bottom of leaves did not see the light and yellow and fall, delay tuberization, cut back on the production. Kind of potato fields in excessive application of nitrogen fertilizer, can make mosaic virus symptom hiding, is not conducive to pull out the plants; and delay the formation of age resistant, virus transmission by aphids, and the proliferation of fast, running to the newborn tuber speed, resulting in seed potato degeneration. Also if the field moisture, plant canopy, resulting in ventilation is poor, provides good environment and conditions for the occurrence of late blight. Lack of nitrogen fertilizer, root development, stunted growth, thin stems, short plant, the leaves become yellow green or gray green, less branched, early flowering and spend less, basal leaves become chlorotic and fall, and to the leaves at the top of the expansion. Severe leaf rollup cup-shaped, in late growth stage, leaf margin of basal leaflets completely chlorotic and crimple, sometimes a fire like and leaf abscission. Potato nitrogen deficiency is not only low yield, but also affects the quality of tubers. Production lack of nitrogen, should be timely topdressing nitrogen fertilizer, usually after the Miao Qi; topdressing should not be too late, the nitrogen application of late, easy to cause leggy stems and leaves, the impact of tuberization.
Phosphorus is plant a variety of important compounds such as components of nucleic acids, nucleotides, phospholipids, also participate in synthesis of carbohydrate, and participate in the decomposition of carbohydrates into simple sugars, provide potato growth of energy. Phosphate fertilizer can promote root development, enhance the plants drought resistance, cold resistance and adaptability. Adequate P, can improve the utilization rate of nitrogen fertilizer, is conducive to the conversion and metabolism of various substances in plant, promote plant early maturing, promote tuber dry matter and starch accumulation, enhancing tuber quality, enhance storability. In acid and heavy soil, available phosphorus is easy to be fixed and can not be absorbed by crops, the potato can only absorb 10%, and about 90% of the phosphorus in the soil can not be absorbed by the potato, and the utilization rate of phosphate fertilizer is very low. In the sandy soil, poor soil fertility, also easy to occur the phenomenon of lack of phosphorus. Potato deficient in phosphorus reduce the number and length of roots, plant growth slow, stem short, stiff, dull green leaves dull, leaf rollup. Phosphorus deficiency in pregnant bud to anthesis, leaf shrinkage, color is dark green, serious basally leaves changed to pale purple, plant froze, petiole, leaf and leaf margin toward, not to start the level, leaf area reduced, color dull green. Phosphorus deficiency is excessive, potato within a block is prone to rust colored necrotic spots or spots throughout the entire tuber flesh, sometimes radiating, cooking russet potato meat harden, affecting the yield and quality. Production on fertilizer should pay more attention to the use of, one-time application foot base fertilizer, because during the growth period, although the compound phosphate foliar application of sufficient, but almost not ease symptoms of phosphorus deficiency.
Potato is a potassium fertilizer, and it needs a lot of potassium. Potassium plays a role in regulating the physiological function, promoting photosynthesis and increasing the assimilation rate of carbon dioxide, and promoting the transportation and accumulation of photosynthetic products. Potassium can regulate cell infiltration and activation of the enzyme activity, adequate potassium fertilizer, plant growth was strong, solid stem, leaf thickness, delay leaf senescence, enhance cold and disease resistance. In addition, potassium fertilizer had an important influence on the quality of potato. Potato potassium deficiency, slow growing internodes short, foliar shrink rough, atrophy of the edge of the blade and the blade tip, tip and leaf margin start is dark green, then yellow brown, and gradually to the full leaf expansion, between the veins with bronze flecks and downward curling and leaflets arranged closely, and leaf stalk formation angle is small, the old leaves of bronze to dry off. Potassium deficiency can cause root stunting and absorption ability is abate, creeping stem length, smaller tubers, with leaf necrosis plant tubers tail development into necrosis, brown concave spots in, cooked tubers potassium deficiency, the potato flesh grayish black. Potassium deficiency symptoms appear later, usually to the tuber formation period was presented, a serious reduction in production. Using nitrogen and potassium fertilizer (potassium nitrate) combined with hoe topdressing during early and middle growth, in the late growth stage of potassium deficiency, general foliar spray 0.2 to 0.3% KH2PO4 every 5 to 7 d sprayed a, ST 2 ~ 3 times.
Calcium is an important component of calcium pectin, which plays an important role in cell wall formation and cell adhesion. Calcium promote root development, regulate the acid-base balance of the body fluid, is an indispensable element in the maintenance of normal physiological and metabolic activities. When calcium plant meristem first victim, plant buds, lateral buds, apical equal health organization first appeared deficiency. In plant morphology of leaf showing variable small lobular coil on the edge and crimple, yellow leaf margin, later necrosis; shorten the internode, on the top of the plant is fascicular shape, leaf, petiole and stem appear mottled. Calcium deficiency, tuber shortening deformity, pith brown and scattered necrotic spots, prone to hollow or black. Seed potato in long-term germination, often due to calcium ion is not easy to transfer characteristics and cause the top of the bud appear Brown necrosis, and even the whole bud necrosis. Calcium excess can affect the absorption of magnesium and trace elements iron and manganese. To prevent calcium deficiency, according to the soil diagnosis, topdressing fertilizer of calcium magnesium borate, emergency spraying boric acid calcium magnesium fertilizer, every 3 to 4 days, a total of 2 ~ 3 times.
Magnesium is the core of the structure of chlorophyll, and it is an important nutrient to maintain the normal growth of stem and leaf. Potato is a crop that is sensitive to magnesium deficiency. Magnesium deficiency of green faded old leaf tip, leaf margin and pulse, and extended to the center, the late brittle, thickening of the lower leaves. Serious when the plant is short, Brown Leaf Chlorosis and necrosis, root growth inhibition. Prevent magnesium deficiency, the first application foot the full maturity of organic fertilizer, soil physical and chemical properties, maintain a neutral soil, necessary but also the application of lime to adjust to avoid soil partial acid or alkali. When in emergency, spraying spraying boric acid calcium magnesium fertilizer, spraying 1 times every 5 d, spraying 3 ~ 4 times.
Long term or continuous application of non - sulfur fertilizer, prone to lack of sulfur. Sulfur deficiency in the potato, plant leaf, leaf vein generally yellows, and lack of nitrogen is similar, slow growth, but leaves not early dry off, serious leaf appear brown patches. Sulfur containing fertilizers such as ammonium sulfate can prevent the sulfur deficiency.
During the growing period of total nutrient foliar fertilizer sprayed such as thousand gold king, shellfish Lukang, and potato plants for normal growth plays an important role, both to increase yield, but also can improve the content of starch, also mixed with disease agents, but also can enhance anti disease effect and improve the disease resistance ability of plants.