The effect of different nitrogen sources from urea and ammonium sulfate on the spikelet number in Egyptian spring wheat cultivars on well watered pot soils

The spikelet number (SPN) is an important wheat yield component decided before anthesis. Our objective was to determine the effect of nitrogen (N) from urea and ammonium sulfate split-applied at different rates before anthesis on the SPN in the recent Egyptian cultivars Sakha93 and Sakha94 and two commonly used cultivars in pots. The response of SPN to applied N from ammonium sulfate was higher than that from urea in all four cultivars used. However, there was no difference in the responses of SPN to absorbed N from the two fertilizers in any of the cultivars. The SPN per applied and absorbed N was the highest in Sakha94 among the four cultivars. These cultivar differences in the SPN were due to the difference in the spike number. The results suggested that the N from ammonium sulfate has a greater effect on SPN than that from urea in recent Egyptian cultivars.