Growth and yield of barley (Hordeum vulgare L.) as affected by nitrogen and phosphorus fertilization and water regimes in Tigray, Ethiopia

The understanding of the interactive effects of abiotic stresses is a crucial issue for improving cereal production in arid environment. For this reason, study was conducted in northern Ethiopia, Tigray region in three sites characterized by different climatic conditions during the cropping season of 2009/10 to understand the agronomic responses of the barley crop to nitrogen and phosphorus fertilization rates combined with supplementary irrigation. Nitrogen (N) and phosphorus (P) fertilizers were applied under three water regimes to ' Sasa' barley variety using split -split plot design with three replications where the sites were treated as a main plot, water regimes assigned to the sub-plot and N and P fertilizers to the sub-subplot. fertilizers and sites had significant (p<0.001) effect on grain yield, thousand grain weight (TGW) and phenological traits. Supplementary irrigation had no effect traits investigated. Most interaction effects, NxP, Nxsite and Pxsite had very significant to significant effects on studied barley traits. Supplementary irrigation x site interaction had significant effect only on thousand grain weight (TGW). Optimum yield, for each site, was obtained from different combination of N and P, implying the need of different recommendation package instead of the general 100 - 100 kg ha(-1) UREA and DAP or combination of 28 and 20kg ha(-1) of nitrogen and phosphorus fertilizers across all barley growing areas. Therefore, universal recommendation of 100 UREA and 100kg ha(-1) DAP should not be treated as best production package for all barley growing areas and this study suggests further thorough investigation for specific NP fertilizers rate recommendation for different barley growing areas.