Evaluation of agronomic traits, biomass productivity, and morphological fractions of Napier grass (Cenchrus purpureus) in Assosa, Northwestern Ethiopia

Nine Napier grass accessions and a local check were evaluated (2016–2018) for agronomic performance, biomass yield, and morphological fractions at the Assosa Agricultural Research Center. The significant (p < 0.001) influence of accession, year, and their interaction on most measured parameters highlights the potential for selecting site-specific, high-performing forage varieties tailored to the Assosa midland and ecologically analogous sub-humid regions of Western Ethiopia. With survival rates up to 98% and a mean dry matter yield (DMY) of 20.69 tonne∙ha⁻¹, these accessions demonstrated adaptability to the acidic soil conditions and unimodal rainfall patterns typical of Western Ethiopia, offering a reliable strategy for bridging the dry season feed gap. Their plant height (254.26 cm) and tillering (mean 16.72) highlight the capacity of these genotypes to produce a high biomass, increasing the livestock carrying capacity and supporting intensive dairy or fattening systems. The leaf-to-stem ratio of 0.81 and leaf proportion of 41.70% suggest a favourable balance between quantity and nutritional quality, as a higher leaf fraction indicates an improved crude protein content and digestibility in ruminants. The variation in DMY and morphological traits suggests that farmers and researchers should prioritise accessions that maximise forage yield and quality and should utilise these high-biomass grasses for biological soil conservation to mitigate the high erosion risks prevalent in midland agroecologies. Considering the biomass yield, nutritional quality, and their stable balance, accessions 16791 and 16813 are recommended for cultivation in the study area and similar agroecologies. Further research should determine their multi-location performance, nutritional quality, and animal performance effects to optimise their utilisation. The adoption of superior accessions could significantly enhance household food security by increasing livestock productivity (milk and meat) and stabilising farming systems against interannual climatic variations.