RESPONSE OF WHEAT (Triticum aestivum L.) VARIETIES TO PHOSPHORUS FERTILIZER RATES AT SHASHEMENE, ETHIOPIA

Abstract

Optimum rate of phosphorus fertilization and use of adaptable variety are important factors in increasing grain yield. Thus, study on the response of wheat varieties to phosphorus fertilizer rates was conducted in 2015 main cropping season at two locations in Shashemene district of Oromia, Ethiopia. The objective was to determine the economically feasible rate of P fertilizer and to assess the effect of P on yield components and yield of wheat varieties. The treatments were three bread wheat varieties (Danda’a, Kubsa, and Digalu) in main plot, and five P levels (0, 46, 92, 138, and 184 kg P2O5 ha-1) in subplot; in split plot design in three replications. Grain yield, harvest index, aboveground biomass yield, and straw yield was significantly (P<0.05) affected by to the main effects of varieties but non-significantly affected by main effects of phosphorus rate and their interactions at both sites; while plant height was significantly varied among varieties but not by phosphorus fertilizer at Allache Harabate and Bute Filicha sites. Spike length was significantly affected by the main factors at the sites, but not by their interaction effect except at Bute Filicha site. Unlike tillers kernels number spike-1 influenced (P<0.05) by interaction of the main factors at Bute Filicha. Grain P content was significant (P<0.05) at Allache Harabate only for varieties but non-significant for phosphorus fertilizer and interactions, where straw P content was variable for varieties (P<0.05) at both sites but not influenced by phosphorus fertilizer and interactions of the main factors; but Puptake was significantly affected due to the interaction effects of variety and phosphorus rates at both sites. Agronomic efficiency was significantly (P<0.05) affected by varieties, phosphorus fertilizer, and their interactions only at Bute Filicha. Highest grain yields of 3093.6 and 2627.7 kg ha-1for variety Kubsa, and 2231.5 and 2080.7 kg ha-1for variety Danda’a was obtained at Bute Filicha and Allache Harabate peasant associations respectively; while for phosphorus application there was an increase in grain yields from 1940 and 1924.9 kg ha-1; to 2370.6 and 2040.7 kg ha-1 in increasing the rate of P applied from nil to 138 kgP2O5ha-1at Bute Filicha and Allache Harabate sites respectively; similar trend was also observed in interaction of variety and phosphorus fertilizer. Highest agronomic efficiency (kg kg-1)was obtained from Digalu (3.6) variety and 138 kgP2O5ha-1 (1.9) phosphorus rate at Allache Harabate; while at Bute Filicha it was from Danda’a variety (12.5) and 138 kgP2O5ha-1 (9.6).The marginal rate of return indicated that highest (69.6%) and (306%) values were obtained from Danda’a variety with 92 kgP2O5ha-1 and Danda’a variety with 138 kgP2O5ha-1 at Allache Harabate and Bute Filicha sites respectively; thus it can be concluded that Danda’a variety with138 kgP2O5 ha-1 followed by Danda’a with 92 kgP2O5 ha-1 was optimum and economically feasible for obtaining satisfactory grain yield of bread wheat crop for the area and similar agro ecologies.