Assessment of Vegetation Composition and Productivity of Rangeland as Affected by Altitude and Grazing Pressure in Kuraz District of South Omo Zone, South Western Ethiopia

The study was conducted in Kuraz district of south Omo Zone, South nation nationalities and people regional state of Ethiopia (SNNPRS), with the objectives of identifying effect of altitude and grazing pressure on vegetation composition and biomass yield of rangeland. Accordingly, a total of 19, 1, 2, 7 and 21 species of grasses, legumes, sedges, other herbaceous plant and woody species were identified in the district, respectively. A. adscensionsis, C. dactylon and S. consililis were the common/dominant species in the communal grazing lands, whereas A. hirtglama, E. choloacolonum, P. geminatum and S. spicatus were common/dominant species in the riverside. In the enclosure grazing sites, E. ch.roxbarghiana, C. dactylon and P. maximum and S. pyramidalis were the common and/or most frequent species. Furthermore, Acacia. sengal, A. mellifer, A. seyel, C. glondelosa and G. erythraea were the common and/or dominant woody species in the communal grazing area, whereas A. seyel, G. erythraea, A. senegal and A. millefera in the riverside. G. villosa, C. africanus, A. oerfota and Mede (local name) were the common and/or dominant species in the enclosure. Almost all the plant species existed in both altitudes. The mean woody density in communal, riverside and enclosure sites of the study district were 2,175, 1963.7 and 1725.5 plants per hectare, respectively. Thus, the wood species density indicated that communal and riverside grazing sites have shown higher number of woody vegetation than enclosure. Total dry matter biomass (DM), DM of grass, and DM of highly desirable grass species were significantly (P<0.05) higher in enclosure (1042, 832 kg/ha and 362 Kg/ha) followed by communal (756.5, 412.5 kg/ha and 47kg/ha) and riverside (621, 355 kg/ha and 50.5 kg/ha). The study indicated that as there was bush encroachment in the study district which resulted in decrease of palatable herbaceous species. Hence, there has to be different interventions on rangeland management practices like bush clearing, paddocking and rotational grazing. Keywords: Biomass, grazing, herbaceous composition, chemical composition, invaders

AMMI and GGE Biplot Analyses for Mega-Environment Identification and Selection of Some High-Yielding Oat (Avena sativa L.) Genotypes for Multiple Environments

This paper reports an evaluation of eleven oat genotypes in four environments for two consecutive years to identify high-biomass-yielding, stable, and broadly adapted genotypes in selected parts of Ethiopia. Genotypes were planted and evaluated with a randomized complete block design, which was repeated three times. The additive main effect and multiplicative interaction analysis of variances revealed that the environment, genotype, and genotype–environment interaction had a significant (p ≤ 0.001) influence on the biomass yield in the dry matter base (t ha−1). The interaction of the first and second principal component analysis accounted for 73.43% and 14.97% of the genotype according to the environment interaction sum of squares, respectively. G6 and G5 were the most stable and widely adapted genotypes and were selected as superior genotypes. The genotype-by-environment interaction showed a 49.46% contribution to the total treatment of sum-of-squares variation, while genotype and environment effects explained 34.94% and 15.60%, respectively. The highest mean yield was obtained from G6 (12.52 kg/ha), and the lowest mean yield was obtained from G7 (8.65 kg/ha). According to the additive main effect and multiplicative interaction biplot, G6 and G5 were high-yielding genotypes, whereas G7 was a low-yielding genotype. Furthermore, according to the genotype and genotype–environment interaction biplot, G6 was the winning genotype in all environments. However, G7 was a low-yielding genotype in all environments. Finally, G6 was an ideal genotype with a higher mean yield and relatively good stability. However, G7 was a poor-yielding and unstable genotype. The genotype, environment, and genotype x environment interaction had extremely important effects on the biomass yield of oats. The findings of the graphic stability methods (additive main effect and multiplicative interaction and the genotype and genotype–environment interaction) for identifying high-yielding and stable oat genotypes were very similar