Comparative analysis of germination, growth, and nutritional composition of Tithonia diversifolia from distinct Peruvian environments

The expansion of sustainable forage systems requires species with high adaptability and stable nutritional quality across environments; however, information on the influence of seed origin on the germination, growth, and chemical composition of Tithonia diversifolia remains limited. Therefore, this study aimed to evaluate the effect of seed environmental origin on germination performance, growth dynamics, and nutritional composition under uniform cultivation conditions. Seeds were collected from two regions of Peru, Pasco (Oxapampa) and Huánuco (Tingo María), and transported to the Universidad Nacional Toribio Rodríguez de Mendoza de Amazonas for controlled evaluation of germination parameters, morphological traits, and chemical composition. Final germination percentage, weighted germination percentage, and germination rate were higher in Oxapampa seeds (p < 0.05), whereas mean germination time did not differ between environment of origin. Plant height and growth rate did not differ significantly between origins throughout most of the evaluation period, except on day 39, when Oxapampa plants showed higher values (p < 0.05). Morphological characteristics were not affected by seed environments of origin (p > 0.05). In contrast, nutritional composition was significantly influenced by both seed origin and regrowth age (p < 0.05), although crude protein, crude fiber, and nitrogen-free extract were not affected by environment of origin (p > 0.05). It is concluded that seed environmental origin influences germination capacity and specific nutritional components, while regrowth age is a key determinant of forage quality. These findings support evidence-based seed selection and harvest management strategies to optimize the use of this species in tropical forage systems.