Yu Zhou Potatoes

Yu Zhou Potatoes

Yu Zhou Potatoes are a product with a geographical indication.

　　Potatoes were introduced to China in the 17th century and have been cultivated in Yu Zhou District for over 300 years. In recent years, superior varieties such as Longshu No.3, Zhuangshu No.3, Qingshu No.168, Qingshu No.9, Jizhangshu No.8, Neishu No.7, Kexin No.1, Atlantic, and Favorita have been introduced. A comprehensive four-tier system for the propagation of virus-free potato seed potatoes has been established. The potato planting area has expanded year by year, with over 90% of the produce being sold outside the region. Yu Zhou potatoes are known for their excellent quality, high starch content, uniform tuber size, and shallow eyes. They are rich in nutrients, with every 100 grams containing 337 kcal of energy, 7.2 grams of protein, 0.5 grams of fat, 77.4 grams of carbohydrates, 1.4 grams of dietary fiber, 20 mg of vitamin A, 120 mg of carotene, 5.1 mg of niacin, 0.28 mg of vitamin E(T), 171 mg of calcium, as well as more than ten types of essential trace elements such as sodium, magnesium, iron, zinc, and selenium needed by the human body. This makes them a highly favored health food. The product has a wide range of uses — it can be consumed or used as feed, while the starch serves as a raw material for various industries. Potatoes have become one of the pillar industries in Yu Zhou District.

　　Geographical Scope

　　Guyuan City’s Yu Zhou District is located in the western part of China's Loess Plateau, at the eastern foothills of the Liupan Mountains. It borders Huan County and Zhenyuan County of Gansu Province to the east; Pingliang City of Gansu Province and Jingyuan and Longde Counties of Ningxia to the south; Xiji and Haiyuan Counties to the west; and Tongxin County to the north. It spans longitude 105°58′–106°30′ and latitude 35°34′–36°38′. The area covers 3,505.9 square kilometers, with currently arable land of 120,666.7 hectares, total production area of 20,000 hectares, and an annual production of 360,000 tons.

　　Natural Ecological Environment and Humanistic Historical Factors

　　(1) Soil and Topography: The terrain and landforms are complex and diverse, with black loam and sandy loam as the main soil types, with a pH of around 7.8. The soil contains 1.0–1.5% organic matter, 0.021–0.111% total nitrogen, 0.10–0.215% total phosphorus, and 2.19–2.53% total potassium.

　　(2) Hydrology: The main river within Yu Zhou District is the Qingshui River, a tributary of the Yellow River. It originates from Heicigou Brain in Kai Cheng Town of Yu Zhou District, flows from south to north through towns such as Yu Zhou and Sanying, exits at Gaoya in Qiyi-ng Town, and then enters the Yellow River via Tongxin and Zhongning. The upper reaches of the Qingshui River, from Kai Cheng to the Guyuan County urban area, have a mineralization level of 0.7 g/L, considered fresh water. At Sanying it is 2.6 g/L, and at Qiyi-ng it is 6 g/L.

　　(3) Climate: The region has a temperate semi-arid climate, with elevations ranging from 1,470 to 2,920 meters. The average annual temperature is 5.7°C–7.5°C, ≥10°C accumulated temperature is 2,160°C–2,560°C, frost-free period is 135–160 days, and sunshine duration is 2,400–2,600 hours. Annual rainfall is 350–650 mm. Precipitation varies due to topography, decreasing gradually from south to north with lower elevation, with a north-south difference of 300 mm. Agricultural irrigation relies on well irrigation, reservoir irrigation, and Yellow River diversion.

　　The air quality is good, with no industrial pollution sources. The main potato production areas are located in the humid southern zone and the arid eastern zone, relying on natural precipitation for cultivation.

　　(4) Humanistic History: In ancient times, Yu Zhou District was a grazing area. After the mid-Ming Dynasty, due to border defense and land reclamation, the population grew rapidly and farming expanded. Since the late Qing Dynasty, crop farming rapidly increased while animal husbandry correspondingly decreased. Potatoes were introduced to China in the 17th century and have been cultivated in Yu Zhou District for over 300 years. With their excellent quality, rich nutrition, high starch content, uniform tuber size, and shallow eyes, they have entered markets in surrounding regions and major coastal cities. The planting area has increased year by year and they have now become one of the pillar industries in Yu Zhou District.

　　Production Technical Requirements

　　(1) Site Selection: Select wheat, flax, or legume stubble fields with light soil texture, deep soil layers, fertile soil, and good permeability for planting. Crop rotation should be at least three years to avoid consecutive cropping, which may lead to infection and damage by late blight and early blight. After the previous crop is harvested, timely deep plowing should be carried out to mature the soil. Proper harvesting and soil preparation should be done during White Dew, and compaction should be carried out in winter and spring to preserve moisture and create favorable soil conditions for sowing and seedling emergence.

　　(2) Variety Selection: Choose disease-resistant, pest-resistant, high-quality, high-yield, stress-resistant, locally adaptable varieties with good marketability that have passed provincial variety approval. In the humid southern zone, Ningshu No.8 is the main variety, supplemented by Zhongxin No.24, Longshu No.3, and Qingshu No.168; in the hilly eastern zone, Jinshu No.7 is the main variety, supplemented by Neishu No.7; in the northern plain water zone, Kexin No.1 is the main variety, supplemented by Atlantic and Favo-rita. Seed potato quality should comply with the requirements of “GB18133 Virus-Free Potato Seed Potatoes” and “CB4406 Seed Potatoes.”

　　(3) Production Process Management, including Special Regulations on the Use of Agricultural Inputs:

　　Field Management: Timely Sowing: To ensure all potato plants emerge before the onset of summer drought and that tuber expansion occurs during the rainy season, sow in mid-to-late April in the northern plain and eastern hilly zones, and in late April to early May in the humid zone. In cases of severe drought preventing timely sowing, the planting period may be postponed to take advantage of available moisture.

　　Weeding: Weeding is generally carried out at least twice during the entire growth period. The first weeding is done when the seedlings are about 10 cm tall after emergence; the second is during the budding stage combined with hoeing. Thereafter, large weeds are removed as needed based on weed growth.

　　Hilling: After potato emergence, promptly check and replant seedlings as necessary, and conduct soil loosening and hoeing. Before budding, hill up soil to form ridges. Combine hilling with topdressing. Apply chemical fertilizer in the middle of narrow rows first, then dig soil from wide rows and hill it up between the narrow rows.

　　Reasonable Fertilization: Given potatoes’ high nutrient demand, preference for potassium, and sensitivity to organic manure, a combination of base fertilizer and topdressing is used. For dry land, apply 45 tons/ha of well-rotted organic manure during pre-sowing plowing. At the budding stage, apply 75 kg/ha of urea once during hilling. For irrigated land, apply 75 tons/ha of well-rotted organic manure per acre during pre-sowing land preparation, and topdress with 75 kg/ha of urea twice during the growing period with irrigation.

　　Pest and Disease Control:

　　① Physical Control

　　Common prevention methods include using disease-resistant varieties, strictly eliminating diseased seed potatoes before sowing, crop rotation, and deep plowing and sunning.

　　② Chemical Control: Common pests and diseases include late blight, blackleg, aphids, grubs,

　　wireworms, and cutworms.

　　(4) Timely Harvesting: The optimal harvest time is when most stems and leaves turn yellow and wither, tuber expansion stops, and tubers easily detach from the plant, indicating physiological maturity. About a week before harvesting, kill the vines. Freshly harvested potatoes should be spread out to dry fully until the skin becomes suberized before transportation or storage.

　　(5) Production Record Requirements: Accurately and truthfully record the entire production process from site selection to harvest and storage of potatoes.

　　Typical Quality Characteristics and Product Quality Safety Standards

　　(1) External Sensory Characteristics: Potatoes are annual herbaceous plants of the Solanaceae family. Also known as “yangyu” or “tudou,” they are commonly propagated asexually, though sexual propagation via seeds is also used. Root morphology differs between tuber-planted and seed-planted potatoes. Based on skin color, varieties are categorized as white-skinned, yellow-skinned, red-skinned, and purple-skinned; flesh color includes yellow-fleshed and white-fleshed types; shapes include round, oval, cylindrical, and egg-shaped. In cultivation, they are often classified by tuber maturity into early, mid, and late maturing, with days from emergence to maturity being 50–70, 80–90, and over 100 days respectively.

　　(2) Internal Quality Indicators: The potatoes from Yuanzhou District are of superior quality, characterized by high starch content, uniform tuber size, and shallow eyes. They are rich in nutrients, with each 100g of the product containing 337 kcal of energy, 7.2g of protein, 0.5g of fat, 77.4g of carbohydrates, 1.4g of dietary fiber, 20mg of vitamin A, 120mg of carotene, 5.1mg of niacin, 0.28mg of vitamin E(T),

　　171mg of calcium, as well as over ten kinds of trace elements needed by the human body such as sodium, magnesium, iron, zinc, and selenium. It is a health food favored by many. The product has a wide range of uses, suitable for both consumption and feed, while the starch can also serve as an industrial raw material.

　　(3) Safety Requirements: Pesticides recommended by the National Agro-Tech Extension and Service Center for use in pollution-free agricultural production are selected. Chemical pesticides should be used scientifically and rationally, with strict control to ensure pesticide residues do not exceed standards, and strict adherence to safe usage intervals.

　　Products from this origin are inspected through point-based and household-based sampling. The sampled products are packed in plastic bags and transported to the Quality Inspection Center of the District Academy of Agricultural Sciences, where they are tested according to the NY5221-2004 "Pollution-Free Food Potatoes" inspection standards.

　　Packaging, labeling, and other related regulations

　　(1) Grading:

　　Grade 1 Potatoes: Exhibit the typical shape of the variety, with consistent shape, shallow and few eyes, intact tuber ratio ≥90%, relatively smooth skin, impurities ≤1%, and commercial potato rate ≥90%.

　　Grade 2 Potatoes: Have the characteristics of the variety, with relatively consistent shape, shallow and fewer eyes, intact tuber ratio ≥85%, slightly rough skin, impurities ≤1%, and commercial potato rate ≥85%.

　　Grade 3 Potatoes: Possess features similar to the variety, with no obvious deformities, medium-depth eyes, relatively few eyes, intact tuber ratio ≥80%, relatively rough skin, impurities ≤2%, and commercial potato rate ≥80%.

　　(2) Packaging: Each package must contain potatoes of the same variety, quality, and grade. Packaging containers should meet hygiene requirements, being clean, dry, non-toxic, and odorless, and suitable for potato packaging, transport, and storage.

　　(3) Labeling: Must comply with national regulations. In addition, product labels should be printed, affixed, or hung on the outside of the packaging. Labels should be clear, not easily detached or faded. The product label must include the following information:

　　— Product name and variety;

　　— Place of origin, producer name, address, and trademark;

　　— Packaging specifications, net weight, and grade;

　　— Packaging date and quality inspector code.

　　(4) Storage:

　　① Quality Requirements Suitable for Storage

　　Potatoes should be stored by category, variety, and grade. Batch-stored potatoes must not have wounds, frost damage, rot, sprouting, or fungal infections.

　　② Optimal Storage Conditions:

　　Optimal Temperature: Potatoes should enter storage as soon as possible after harvest. Within the first 10 days of storage, the temperature should be maintained at 13–18°C with higher relative humidity to facilitate wound suberization and healing. After that, the temperature must be lowered as soon as possible to between 3°C and 5°C. During the last two weeks of storage, the temperature should be increased to between 12°C and 20°C.

　　Optimal Humidity: The optimal humidity is between 85% and 95%.

　　Air Circulation: The containers and stacking method for potatoes should allow for free air circulation.

　　(5) Transportation: Transport vehicles should be clean and hygienic, equipped with rainproofing and ventilation facilities.