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Genotypic and environmental factors influence the proximate composition and quality attributes of sweetpotato (Ipomoea batatas L.)

Abstract:

Background: Sweetpotato is an important staple food crop worldwide. The genotype mainly influences the nutritional quality of its storage roots, but environmental conditions could produce significant variations in chemical composition and quality. The aim of this study was to characterize sweetpotato diversity of 20 selected genotypes and identify harvest time (90, 120, and 150 days after planting-DAP) and environmental effects on quality attributes estimated by proximate analysis (dry matter, ash, crude fiber, total protein, and total soluble solids). Red (R), green (G), and blue (B) (RGB) analysis was used to characterize the genotypes phenotypically. Results: The results of the current study revealed that flesh color was associated with proximate composition. RGB analysis showed that low B pixel values were present in yellow–orange- and purple-fleshed genotypes, which simultaneously exhibited high total protein content (TPC), ash content (AC), and crude fiber (CF), while cream- and white-fleshed genotypes showed high B pixel values and were related to high dry matter content (DMC). In these genotypes, the high DMC was maintained or increased through harvest time, however, a reduction in the proportion of accumulated AC and TPC was observed. On the other hand, in the pigmented genotypes, DMC increased up to 120 DAP, showing major stability in terms of AC and TPC. Regardless of harvest time, more intense rain events 30 days before harvest, affected the storage of DMC in roots negatively, while AC, TPC, and CF were accumulated more efficiently, or their proportion increased. High temperatures increased total soluble solids (TSS) accumulation and reduced AC, TPC, and CF accumulation. The combined analysis, according to the additive main effects and multiplicative interaction (AMMI) model, confirmed these results. Conclusions: These findings indicated that white-fleshed genotypes contain high DMC, although, with lower TPC, AC, and CF contents compared to yellow–orange- and purple-fleshed genotypes. Although there is an increase in DMC in extended harvests (in orange-fleshed genotypes up to 120 DAP), the presence of pre-harvest rain promotes its translocation and loss. On the contrary, TPC, AC, and CF can be kept stable or even increase, except in environments with high temperatures that induce low accumulation. The current study provides a better understanding of the nutritional response of sweetpotato diversity under several growing conditions, which can be recognized and used integrally to improve food quality.