Bioscience Evidence 2026, Vol.16, No.4, 329-344 http://bioscipublisher.com/index.php/be 334 while low reducing sugar content is required to prevent excessive browning and undesirable flavors during frying. Processing varieties for French fries generally require dry matter contents above approximately 19.5%, whereas chip-processing varieties should reach about 20% dry matter while maintaining low reducing sugar levels (Hussen, 2019). Lady Rosetta and Courage are considered suitable cultivars for chip production (Islam et al., 2022), whereas Fontane is particularly suitable for frying because of its high dry matter content, low reducing sugar level, firm texture, and low browning susceptibility (Bedini et al., 2024). For processing into potato flour, noodles, steamed bread, baked products, natural pigments, or functional ingredients, selection criteria should be adjusted according to the final application. High-dry-matter genotypes are more suitable for flour-based products, whereas some anthocyanin-rich materials are better suited for pigment extraction or functional product development rather than conventional starch-oriented processing. For colored potatoes intended for processing, anthocyanin content should be considered in addition to conventional indicators such as dry matter and starch content. 4 Differences among Production Regions and Ecological Conditions 4.1 High-altitude and cool-climate production areas High-altitude and cool-climate regions in western China, including Yunnan, Guizhou, Gansu, Qinghai, and related plateau or mountainous areas, are generally favorable for tuber coloration and phytochemical accumulation in colored potatoes. However, these responses are strongly influenced by genotype and altitude range. In Yunnan, tuber color intensity of purple and red potatoes increased as altitude increased from approximately 1 800 to 3 300 m. Total phenolics, total flavonoids, total anthocyanins, and anthocyanin biological yield continued to increase until approximately 2 800 m altitude (Wu and Xiao, 2024). A controlled temperature experiment using local colored potato varieties from Yunnan further supported this field observation. Moderate low-temperature conditions improved yield and secondary metabolite accumulation, particularly anthocyanins, whereas excessive low temperature (10 ℃) caused leaf damage and potentially inhibited tuber formation and pigmentation (Chen et al., 2024). Studies conducted in southwestern and northwestern China indicate that high altitude improves not only tuber coloration but also some basic quality traits. In Sichuan, purple potato cultivar ‘Ziyun 1’ showed continuous increases in yield, crude protein, starch, and anthocyanin contents when grown from 800 to 2 500 m altitude, while soluble sugar content decreased. The high-altitude region was considered suitable for producing high-yield and high-quality purple potatoes (Zheng and Zhang, 2013). Among colored potato clones grown at different altitudes, anthocyanin content was highest at high altitude and lowest at intermediate altitude, with significant differences among purple and red clones in pigment content and composition (Qi et al., 2023). A multi-environment trial conducted in Gansu included humid plateau, semi-arid, and arid regions, and demonstrated that genotype × environment interactions significantly affected all yield and quality traits. Vitamin C, reducing sugars, and carotenoids were particularly sensitive to environmental variation. G25 performed best for yield, dry matter, and carotenoid accumulation in humid Weiyuan, G18 showed better adaptation to semi-arid Anding, and G7 was more suitable for arid Yongchang. These results indicate that cool-climate regions are not homogeneous and require site-specific cultivar matching (Zhou et al., 2025). High-altitude and cool-climate regions also face practical production constraints. Experimental sites in Gansu differed greatly in altitude, rainfall, sunshine duration, and frost-free period, with annual precipitation ranging from 185 to 550 mm and frost-free periods from 134 to 166 days, indicating simultaneous risks of drought and short growing seasons (Zhou et al., 2025). Under Arctic-like cool conditions, many colored potato varieties behaved as late-maturing types and were unsuitable for early production, even when final yields were acceptable (Liu et al., 2023). 4.2 Northern dryland production areas In northern dryland regions, including Inner Mongolia, Ningxia, Shaanxi, Hebei, and adjacent sandy or oasis areas, abundant solar radiation favors tuber dry matter and starch formation, whereas limited rainfall makes water
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