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Dec 31, 2025Keywords:
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Main Article Content
Agronomic and Morphological Determinants of Sweet potato Growth and Yield in Humid Tropical Ultisols
Abstract
Sweet potato (Ipomoea batatas (L.) Lam.) productivity in humid tropical regions is strongly influenced by varietal morphology and agronomic performance, particularly under Ultisol conditions characterized by low inherent fertility and high rainfall. Field experiments were conducted during the 2020 and 2021 cropping seasons to evaluate the agronomic and morphological determinants of sweet potato growth and yield in a humid tropical Ultisol. Six sweet potato varieties differing in flesh color and genetic background were assessed for vine length, branching, leaf production, and yield components using a randomized complete block design. Vine length did not differ significantly among varieties at 4 weeks after planting (WAP) in both seasons; however, significant varietal differences emerged at 8 WAP. Umuspo4 consistently produced longer vines, while TIS 87/0087 showed comparable vine elongation in 2021. Branching and leaf production were significantly influenced by variety at early growth stages, with Umuspo4 and TIS 87/0087 exhibiting superior canopy development. Leaf number increased markedly between 4 and 8 WAP, reflecting rapid vegetative expansion under humid conditions. The number of storage roots per plant did not vary significantly among varieties at harvest in either season. In contrast, storage root weight and total root yield were significantly affected by variety in 2020, with orangefleshed Umuspo1 and Umuspo3 producing the highest yields. Umuspo3 out-yielded other varieties by up to 473.6% in 2020, whereas varietal yield differences were not significant in 2021, indicating strong seasonal effects. The results demonstrate that morphological traits such as vine length, branching, and leaf production are important determinants of sweet potato growth in humid tropical Ultisols, but yield expression is primarily driven by efficient assimilate partitioning and genotype-by-environment interactions. Orange-fleshed Umuspo3 showed superior yield potential and adaptability, making it a promising variety for cultivation in Ultisol-dominated humid tropical agroecologies.
