Effect of Phosphorus Rates and Varieties on Grain Yield, Nutrient Uptake and Phosphorus Efficiency of Tef [ Eragrostis tef (Zucc.) Trotter]

Abstract

Tef [Eragrostis tef (Zucc.) Trotter] is the major cereal crop in Ethiopia. Increasing tef yield requires improving soil phosphorus (P) supply and identifying P efficient varieties. An experiment was conducted at Wenago, Ethiopia, from May to August, 2011, during the main cropping season, to investigate the role of P supply in relation to grain yield, nutrient uptake (N, P, Ca and K) and P efficiency, and to investigate varietal differences for these parameters using four P rates (0, 3, 6 and 9 g/m2 P2O5) as main plots and three tef varieties (DZ-Cr-37, DZ-Cr-82, and DZ-Cr-255) as subplots in split-plot design with three replications. For respective 0, 3, 6 and 9 g/m2 P2O5, grain yield was 84, 203, 215 and 218 g/m2, total biomass 586, 897, 971 and 1016 g/m2, and harvest index 0.14, 0.23, 0.22 and 0.22. For respective variety DZ-Cr-37, DZ-Cr-82, and DZ-Cr-255, grain yield was 194, 182 and 163 g/m2, total biomass 810, 922 and 871 g/m2, and harvest index 0.24, 0.19 and 0.18. Total plant nutrients (g/m2) for respective 0, 3, 6 and 9 g/m2 P2O5 were N 3.92, 7.95, 9.49 and 10.80, P 0.57, 1.20, 1.49 and 1.66, calcium 0.16, 0.27, 0.38 and 0.45, and K 4.45, 7.96, 9.70 and 10.50. For respective 3, 6 and 9 g/m2 P2O5, P physiological efficiency (PE) was 224, 153 and 127, apparent recovery (AR) 0.49, 0.36 and 0.28, and agronomic efficiency (AE) 92, 50 and 35. For respective variety DZ-Cr-37, DZ-Cr-82 and DZ-Cr-255, PE was 248, 130 and 126, AR 0.28, 0.44 and 0.41, and AE 68, 57 and 51. The present experiment suggests that excess P supply beyond 3 g/m2 could result in low grain yield increase and low P recovery requiring soil P assessment prior to fertilizer application. Moreover, variety DZ-Cr-37 may be incorporated in the future breeding programs for P efficiency in tef.