Molecular Plant Breeding 2024, Vol.15, No.6, 379-390 http://genbreedpublisher.com/index.php/mpb 385 virus disease (SPVD) demonstrate that combining traditional methods with advanced techniques such as marker-assisted selection and genetic engineering can effectively overcome the limitations of conventional breeding (Ngailo et al., 2013). Beyond disease resistance, improving the nutritional quality of sweet potato varieties, especially in Africa, also showcases the potential of breeding programs to address societal challenges. Work led by the International Potato Center (CIP) focuses on developing varieties rich in essential nutrients like vitamin A. Targeted breeding programs addressing nutritional deficiencies can significantly impact public health, particularly in regions with high rates of malnutrition (Ojwang et al., 2023). These initiatives maximize the social and economic benefits of agricultural innovation, together demonstrate the effectiveness of breeding programs in balancing agricultural, nutritional, and societal goals. 6 Yield and Performance Analysis of Improved Varieties 6.1 Yield trials and comparative studies Yield trials and comparative studies are essential for evaluating the performance of different sweet potato genotypes under various environmental conditions. For instance, a study conducted in Odisha, India, evaluated fifteen sweet potato genotypes and found significant variability in traits such as vine length, number of branches per plant, and root yield per plant, which are crucial for yield improvement (Kar et al., 2022). Similarly, in Indonesia, yield stability analysis using AMMI and GGE biplot models identified stable genotypes like F1-038 and F1-069, which showed higher yields across different agroecosystems (Karuniawan et al., 2021). In Ethiopia, genetic variability studies on twenty sweet potato varieties revealed significant differences in tuber yield and other agronomic traits, indicating the potential for selecting superior varieties for breeding programs (Tessema et al., 2022). 6.2 Factors influencing yield performance Several factors influence the yield performance of sweet potato varieties. Genetic diversity plays a crucial role, as seen in the study from Odisha, where traits like root girth and β-carotene content were positively correlated with total root yield per hectare (Kar et al., 2022). Environmental conditions also significantly impact yield, as demonstrated in the Indonesian study, where location-specific genotypes were identified based on their performance in different agroecosystems (Karuniawan et al., 2021). Additionally, the physiological status of seed tubers and environmental factors like frost can affect yield, as observed in the Andean potato study, where genotypic differences were evident under simulated frost scenarios (Condori et al., 2010). 6.3 Statistical analysis of yield data Statistical analysis is vital for interpreting yield data and making informed decisions in breeding programs. In the Odisha study, analysis of variance (ANOVA) and D2 statistics were used to assess genetic variability and divergence among genotypes (Kar et al., 2022). The Indonesian study employed combined variance analysis, AMMI, and GGE biplot models to evaluate yield stability and identify superior genotypes (Karuniawan et al., 2021). In Ethiopia, broad-sense heritability and genetic advance were calculated to determine the potential for genetic improvement in sweet potato varieties (Tessema et al., 2022). These statistical methods provide a robust framework for understanding the genetic and environmental factors influencing yield and for selecting high-performing genotypes for crop improvement. 7 Environmental Adaptation of Sweet Potato Varieties 7.1 Adaptation to diverse climatic conditions Sweet potato varieties exhibit significant genetic diversity, which is crucial for their adaptation to diverse climatic conditions. Studies have shown that sweet potato production is at risk from extreme heat events, but certain tolerant cultivars can thrive and potentially provide climate resilience (Figure 3) (Heider et al., 2020; Pironon and Gomez, 2020). In West Africa, the genetic diversity of sweet potato is structured along a climatic gradient, with specific genetic groups adapted to particular climatic areas, such as tropical humid or Sahelian climates (Glato et al., 2017). This diversity is essential for developing strategies to adapt agriculture to ongoing climate variations.
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