Leaf Photosynthesis, Nitrogen Use Efficiency, and Relationships with Growth and Yield in Teff

Abstract Background: Teff (Eragrostis tef (Zucc.) Trotter) is an important grain crop, but a paucity of research means that the mean yield is below 1.5 t ha−1. Its high genetic diversity has not been exploited to improve its yield potential. Previous efforts at increasing yield were based entirely on phenotypic, morphologic, and agronomic merits. However, photosynthetic capacity has been neglected, so its possible contributions to yield improvements remain unexplored. Results: We grew 15 teff cultivars in a controlled environment to explore variations in photosynthetic capacity and nitrogen use efficiency (NUE), and examined the relationships of gas exchange and NUE before anthesis with growth and yield attributes. Substantial differences were found in leaf photosynthetic rate (19 ± 9 μmol m−2 s−1, mean ± SD), stomatal conductance (0.11 ± 0.09 mol m−2 s−1), and transpiration rate (2.4 ± 1.3 mmol m−2 s−1). The cultivars differed significantly (P < 0.05) in both NUE (190 ± 227 g m−2) and photosynthetic NUE (59 ± 34 µmol g−1s−1). On average, the plants partitioned 29% of N to leaf, 28% to panicle, and 13% to stem before anthesis. Yield and biomass production were closely associated with photosynthetic capacity and NUE. Clustering of the cultivars on the basis of photosynthesis, NUE, growth, and yield indicates wide variations in photosynthetic capacity and NUE in the wider teff gene pool that should be exploited. Conclusion: We conclude that leaf photosynthesis and NUE are positively related to yield and biomass production in teff.