Genotype by Environment Interaction Analysis and Stability Study of Elephant grass (Pennisetum purpureum) Genotypes at Lowlands of East Hararghe zone of Oromia, Ethiopia

Elephant grass could play an important role in providing a considerable amount of quality forage for mixed farming system. Thus, the study was conducted to evaluate and identify stable and high-yielding elephant grass genotypes for herbage dry matter yield, nutritional quality and performance for major agronomic traits. Ten elephant grass genotypes and one elephant grass variety (Zehone-02) as standard checks were used as experimental materials. The genotypes were arranged in a randomized complete block design (RCBD) with three replications. The combined analysis of variance for herbage dry matter yield, plant height, tiller number and leaf to stem ratio over six locations revealed significant (p<0.001) variation due to genotypes by environment interaction. The analysis of variance revealed substantial (p<0.001) differences between genotypes for herbage dry matter yield, leaf to stem ratio, tiller number and plant height. The concentrations of NDF%, TA% and IVDMD differed significantly (p<0.001), while the results for the other quality indicators were not. The genotype ILRI 16803 had the highest herbage dry matter yield (45.24 t/ha) and leaf to stem ratio value (2.86) over other tested materials. The genotype ILRI-16803 had showed 31.17% yield advantage over the standard check (Zehone-02 variety) (31.14 t/ha/year). Genotype by environment interaction analysis also showed that genotype ILRI-16803 was more stable across locations. Therefore, elephant grass genotype ILRI-16803 was the highest yielder and most stable across the study sites, indicating the genotype’s potential for cultivation as well as to be released as a variety.