Agro-morphological performance, nutritive value and dry matter yield stability of mission grass (Pennisetum polystachion (L.) Schult) genotypes in multi-environment trials in Western Oromia, Ethiopia

Mission grass (Pennisetum polystachion (L.) Schult) is a promising forage crop due to its adaptability and productivity. Feed scarcity, both in quantity and quality, is a major constraint to animal production, limiting productivity and sustainability in livestock systems. Addressing this challenge requires the development and adoption of improved forage technologies to bridge feed gaps. This study was carried out to evaluate and identify high herbage dry matter yield, stable and better nutritional quality of Mission grass under varying environmental conditions in Western Oromia.Four Mission grass genotypes were evaluated against the standard check (Nechsare) across three locations (Haro Sabu, Kombo and Ayira) during the 2021–2022 main cropping seasons. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Data such as plant height, number of tiller and leaves, leaf to stem ratio and herbage dry matter yield were collected, the nutritional quality was analyzed based on standard procedures and the collected data were subjected to analysis of variance (ANOVA). The Additive Main Effects and Multiplicative Interaction (AMMI), AMMI stability value, Genotype selection index and genotype and genotype by environment interaction (GGE) models were used to assess genotype-by-environment (G×E) interactions and stability. The measured and collected data of the genotypes were analyzed using SAS and the mean separation of least significance difference (LSD). Combined analysis of variance revealed highly significant differences (p < 0.01) among genotypes, environments, and their interactions for agronomic traits and herbage dry matter yield. In the AMMI analysis, the environmental factors contributed the largest proportion (58.20%) of the total variation, followed by genotype (26.82%) and G×E interaction (14.98%). Among the tested genotypes, NG-0121 produced the highest mean herbage dry matter yield (8.79 tha− 1), followed by NG-0057 (7.35 tha− 1). Stability analysis of AVS and GSI confirmed that NG-0121 and NG-0057 were high-yielding and relatively stable, outperforming the standard check by 43.86% and 20.29%, respectively. Additionally, these genotypes exhibited favorable crude protein content and digestibility. The study identified NG-0121 and NG-0057 as superior Mission grass genotypes with high yield potential, relatively stable, and desirable nutritional attributes. Given their high yield advantage over the standard check (Nechsare) and adaptability across different environments, NG-0121 and NG-0057 genotypes are recommended for variety verification and potential release in Western Oromia and similar agro-ecologies to enhance forage availability and livestock productivity.