Muhaba, Sofiya K.Dakora, Felix D.2024-10-212024-10-212020-05-27https://www.semanticscholar.org/reader/191783https://hdl.handle.net/20.500.14519/886Phosphorus is a key nutrient element involved in energy transfer for cellular metabolism, respiration and photosynthesis and its supply at low levels can affect legume nodulation, N2 fixation, and C assimilation. A two-year field study was conducted in Ethiopia in 2012 and 2013 to evaluate the effects of P supply on growth, symbiotic N2 nutrition, grain yield and water-use efficiency of three groundnut genotypes. Supplying P to the genotypes significantly increased their shoot biomass, symbiotic performance, grain yield, and C accumulation. There was, however, no effect on shoot δ13C values in either year. Compared to the zero-P control, supplying 40 kg$ha–1 P markedly increased shoot biomass by 77% and 66% in 2012 and 2013, respectively. In both years, groundnut grain yields were much higher at 20 and 30 kg$ha–1 P. Phosphorus supply markedly reduced shoot δ15N values and increased the %Ndfa and amount of Nfixed, indicating the direct involvement of P in promoting N2 fixation in nodulated groundnut. The three genotypes differed significantly in δ15N, %Ndfa, N-fixed, grain yield, C concentration, and δ13C. The phosphorus genotype interaction was also significant for shoot DM, N content, N-fixed and soil N uptake.455-466 PagesenAttribution-NonCommercial-ShareAlike 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-sa/4.0/shoot yieldN-fixed%Ndfaδ15Nδ13CWater-use efficiencyArticle