Molecular Soil Biology 2025, Vol.16, No.4, 175-187 http://bioscipublisher.com/index.php/msb 1 77 and challenging climatic conditions is essential. For instance (Hanume et al., 2024), found that the drought tolerant genotypes including Dhenkanal local-2, 84×14, SB21/57, Howrah, S-783 and 84×1 exhibited low yield reduction ratio, which guide breeding programs aimed at improving yield under drought conditions. In a word, high-yield varieties not only ensure better productivity, even under stressful conditions, but also contribute to the economic stability of farmers. 2.2 Genetic variation and breeding strategies Genetic variation within a species is the foundation of plant breeding because it allows breeders to select and combine different traits to create new varieties. In sweet potatoes, this variation can be found in traits such as yield, root size, shape, color, taste, nutritional content, and resistance to abiotic stresses and diseases (Vargas et al., 2020; Mahmud et al., 2021). To maximize genetic yield potential., breeders often focus on combining high yield with other desirable traits such as disease resistance, drought tolerance, and quality attributes (Otoboni et al., 2020; Rahmawati et al., 2021). This requires a deep understanding of the genetic basis of yield and how it interacts with environmental factors. Various techniques, such as quantitative trait locus (QTL) mapping and genomic selection have been used to identify the genes and alleles associated with high yield. using a mapping population consisting of 202 individuals derived from a cross between Xushu18 (a high yield cultivar) and Xu781 (a low yield line) (Li et al., 2014) mapped nine major QTLs for storage root yield of sweet potato. starch content, which is negatively correlated with fresh yield, is contributed by gene IbPMA1. Overexpression of IbPMA1 in sweet potato results in significantly increased starch and sucrose contents, while its knockdown exhibits an opposing effect (Jiang et al., 2024). The use of selection indexes, such as the one proposed by Mulamba & Mock, has been instrumental in achieving genetic gains in sweet potato breeding (Vargas et al., 2020). Moreover, breeding efforts have incorporated advanced techniques like marker-assisted selection and genetic engineering to enhance the efficiency of developing high-yield varieties (Ngailo et al., 2013). For example, the CropInd tool has been utilized to estimate agronomic performance and stability of sweet potato genotypes, aiding in the selection of superior varieties like 0113-672COR for specific regions (Rosero et al., 2023). Additionally, reciprocal crosses and the study of maternal effects have provided insights into the inheritance of yield and quality traits, further improving breeding strategies (Lin et al., 2007). Several studies highlight the successful adoption of high-yield sweet potato varieties across different regions. In Bangladesh, the evaluation of four popular varieties ('BARI Mistialu-8', 'BARI Mistialu-12', 'BARI Mistialu-14', and 'BARI Mistialu-15') across multiple environments demonstrated significant yield improvements. 'BARI Mistialu-12' emerged as the highest yielder, followed by 'BARI Mistialu-8' and 'BARI Mistialu-14', showing 57.89%, 61.50%, and 44.30% higher yields than the local check cultivar, respectively (Mahmud et al., 2021). Similarly, in Indonesia, the stability and yield potential of Orange-Fleshed Sweet Potato (OFSP) genotypes were assessed using AMMI and GGE biplot models. Genotypes F1-038 and F1-069 were identified as the most stable and high-yielding, making them suitable for recommendation as superior varieties for West Java (Karuniawan et al., 2021). These studies underscore the effectiveness of breeding programs and the importance of selecting high-yield varieties tailored to specific environmental conditions. 3 Soil Management Practices 3.1 Ideal soil conditions for sweet potato growth Sweet potatoes produce best in well-drained, light, sandy loam or silt loam soil with a pH range of 5.5 to 6.6 (Kihurani, 2008).These conditions facilitate root development and nutrient uptake, both of which are essential for high yields (Kennedy, 2022). Controlled experiments have demonstrated that soil pH level can significantly affect the quality of sweet potatoes, with certain pH ranges being more conducive to higher dry matter content. Therefore, managing soil pH through appropriate amendments and practices can enhance nutrient availability, promote healthy root development, and support beneficial microbial activity, all of which are crucial for high crop yields and maintaining soil health over the long term (Navarro et al., 2020; Agbede and Oyewumi, 2022). Additionally, maintaining soil moisture through practices like straw mulching can improve soil humidity, decrease transpiration, and cool the soil, which is especially beneficial in dry and hot regions (Waheed et al., 2023).
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