Identification and Prevention of Physiological Disorders in Atlantic Potato Tubers

The Atlantic potato is a high-quality raw material for processing snack foods such as potato chips and French fries. Its growth period is relatively short, and it has strict requirements for the cultivation environment: it needs cool conditions but is not tolerant of low temperatures. During cultivation, freeze protection and fertilizer and water management should be done well to avoid physiological disorders such as black heart, hollow heart, starch leakage, cracking, and deformities, and to improve tuber quality and marketable yield.

I. Tuber black heart

1. Symptoms: Irregular patterns ranging from black to blue appear in the center of the tuber. When oxygen deficiency is severe, the entire tuber may turn black. Usually the boundary between diseased tissue and healthy tissue is relatively distinct. This is caused by oxygen deficiency inside the tuber.

2. Prevention: The main point is to maintain good ventilation of the potato pile during storage and to maintain a suitable storage temperature. Room temperature must be kept between 1-3°C, relative humidity should be kept below 85%, and air circulation should be maintained. During storage, different varieties should be stored separately, not mixed with seeds, chemical fertilizers, and the like, and not placed in places with heavy smoke or gas, so that the potatoes will not become moldy or sprout.

II. Tuber hollow heart

1. Symptoms: Hollow heart mostly occurs in the pith of the tuber, with no external symptoms. Generally, large tubers are prone to hollowing. The hollow is mostly star-shaped and radiate or oval, and sometimes several cavities connect together. The cavity walls are white or brown. Before hollowing appears, the tissue is water-soaked or translucent. Internal tissue tension increases and causes cracking, and some substances are transferred or absorbed by other parts. The cause of hollow heart is excessively rapid tuber enlargement.

2. Prevention: The main measure is to maintain suitable soil moisture during the tuber enlargement period, and to plant at a reasonable density, increase potassium fertilizer application, and pay attention to hilling. The Atlantic potato has a high fertilizer requirement, so sufficient base fertilizer should be applied, with base fertilizer accounting for 50%-60%, mainly organic fertilizer and phosphorus and potassium fertilizer. Organic fertilizer requires more than 1500-2000 kg per mu, applied when preparing the beds. For chemical fertilizer, choose a sulfur-containing compound fertilizer with nitrogen, phosphorus, and potassium contents all at 15%, 50 kg per mu, applied before sowing by opening furrows or holes in the middle of the bed, and take care that the fertilizer does not directly contact the seed potatoes to avoid burning the seed potatoes. Topdressing should be done early and skillfully, generally in 2 applications. The first topdressing is done when the seedlings are fully emerged, and thin human manure and urine can be used for watering to ensure the nitrogen fertilizer needed for the growth of potato seedlings and lay a foundation for mid- and late-stage growth. Combined with intertillage and hilling, apply 500-700 kg of decomposed human manure and urine diluted with water. The second is at the bud stage, when potato tubers begin to enlarge and the fertilizer requirement increases; this is the period of greatest fertilizer demand, mainly potassium fertilizer, with an appropriate amount of nitrogen and phosphorus fertilizer, to meet the needs of tuber formation. In fertilization, attention should be paid to applying appropriate nitrogen and increasing potassium to prevent excessive vine growth without tuber formation. If too much nitrogen is applied and excessive vegetative growth occurs, spraying with a 0.02% magnesium sulfate solution can inhibit excessive growth, and generally 5-15 kg of compound fertilizer can be applied per mu. After the rows close, topdressing can be stopped. Throughout the growth process, generally 2-3 intertillages are required. At full seedling emergence, the first deep intertillage is carried out together with thinning of seedlings to increase soil temperature and promote seedling growth; at the rosette stage, the second intertillage and shallow hilling are carried out to favor more tuber formation; before row closure, the third intertillage and hilling are carried out, with cumulative hilling thickness of 10-20 cm and bed height of 35-40 cm. Hilling can thicken the tuber-bearing layer, effectively increase yield, and at the same time prevent tubers from being exposed and turning green, which reduces quality.

III. Starch leakage and tuber cracking

1. Symptoms: At harvest, "white spots" or "lumps" or potato skin ulceration can often be seen on the surface of some tubers; some tubers show one or several longitudinal cracks, with the surface covered by healed periderm tissue. This is tuber cracking. The cracks vary in width and length and seriously affect the marketable rate. During the rapid growth stage of tubers, if drought occurs and irrigation and timely topdressing are not carried out, or if the tubers are under conditions of high temperature and high humidity or high temperature and drought for a long time, the starch in the tubers leaks out toward the skin, producing "white spots" or "lumps" or potato skin ulceration; in some cases, internal pressure exceeds what the skin can bear and cracks form, and as the tubers enlarge, the cracks gradually widen. Sometimes the cracks gradually "grow smooth," and at harvest only "traces" are seen. The main cause is that the soil alternates between dry and wet. During drought, the tuber forms periderm and enlarges slowly; when moist, the plant absorbs more water and the tuber enlarges quickly, causing the periderm to rupture. In addition, excessive soil fertilizer and water during the enlargement period can also easily cause cracks in the tuber skin.

2. Prevention: The main measure is to increase organic fertilizer application to ensure that soil fertility remains uniform; at the same time, water timely to ensure moderate soil moisture content during the tuber enlargement period and avoid soil drought; good soil aeration should also be maintained. Generally, high-bed cultivation can be adopted, with deep side ditches. The ditch depth should be more than 50 cm, and all ditches should be connected so that field water can be drained quickly when it rains. At the same time, weed overgrowth in the field should be prevented and controlled, and before the rainy season, ditches should often be cleared to prevent waterlogging.

IV. Tuber deformities

1. Symptoms: Deformed tubers are mostly formed by secondary tuber enlargement. There are many types of deformities: tumorous tubers, that is, protrusions at the bud eye parts of the tuber forming small tumor-like tubers; dumbbell-shaped tubers, that is, a "thin neck" formed near the top of the tuber; secondary tubers, that is, tubers formed again on the tuber; new branches and leaves produced on the tuber; and chain-like secondary growth, that is, stolons growing from the tuber and then forming tubers. The main cause of secondary growth is the alternating occurrence of high temperature, drought, and high humidity, or the return of weather to normal after freeze damage, and so on. Any external conditions that can cause tubers to develop abnormally can cause deformities in tubers.

2. Prevention: The main point is to maintain suitable conditions for tuber enlargement, that is, increase organic fertilizer application to increase soil fertility; carry out appropriate deep plowing, pay attention to intertillage and prevent freeze damage, and maintain good soil aeration; keep the soil moist without becoming waterlogged, and water during drought.