International Journal of Horticulture, 2025, Vol.15, No.1, 41-50 http://hortherbpublisher.com/index.php/ijh 42 2 Agronomic and Environmental Requirements 2.1 Growth requirements for fresh-eating sweet potatoes: soil, temperature, and rainfall Fresh-eating sweet potatoes thrive in well-drained, sandy loam soils with a pH range of 5.5 to 6.5, although they tolerate soils with moderate nutrient levels (Motsa et al., 2015). Ideal temperatures for growth are between 21 °C and 26 °C. Excessively high temperatures favor vine growth over tuber development, while night temperatures below 15 °C reduce productivity. Rainfall of 500-700 mm throughout the growing season is optimal (Navarro et al., 2020), with a need for adequate moisture during the early establishment phase but less during the root development period (Zhapar et al., 2023; Li, 2024b) (Figure 1). Figure 1 Cultivation of fresh-eating sweet potatoes and drip irrigation under suitable environmental conditions: chemical and biological changes in the soil, DAP = days after planting (Adopted from Navarro et al., 2020) 2.2 Opportunities and challenges of sweet potato cultivation in subtropical regions Subtropical regions provide favorable conditions for growing sweet potatoes, but challenges such as irregular rainfall patterns and heat stress limit consistent production. Climate change adds unpredictability, but the crop's resilience makes it suitable for sustainable agriculture. Opportunities include using improved, high-yield varieties like orange-fleshed sweet potatoes (OFSP) to meet both nutritional demands and market preferences. Moreover, smallholder farmers benefit from the crop’s short maturity period and ability to grow in marginal soils (Cheboi et al., 2024; Motsa et al., 2015). 2.3 Nutritional and management needs at different growth stages Fresh-eating sweet potatoes have distinct nutrient needs across growth stages. Early in the season, nitrogen promotes vine growth, but excess nitrogen can reduce tuber yield if not managed properly. Phosphorus is essential during establishment for root development, while potassium supports tuber formation and enhances disease resistance later in the season (Li, 2024a). Nutritional deficiencies-especially in nitrogen, potassium, and boron-can lead to poor vine health or low-quality tubers (Zhapar et al., 2023). Proper irrigation is critical in the early growth stages, with reduced watering during harvest to prevent tuber rot. 3 Overview of High-Yield Fresh-Eating Sweet Potato Varieties 3.1 Common fresh-eating sweet potato varieties and their traits in subtropical regions Beauregard and Jewel are among the most popular fresh-eating varieties grown in subtropical regions. Beauregard is valued for its high beta-carotene content, sweet flavor, and high yield, often exceeding 20 tons per hectare under optimal conditions (Motsa et al., 2015). Jewel, known for its smooth texture and resistance to cracking, also
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