Response of Autumn Sugar Beet Varieties to Nitrogen Application and Its Efficiency Indices

This research was conducted to investigate the response of autumn-planted sugar beet varieties to nitrogen and parameters of its efficiency. The experiment was arranged as factorial in a randomized complete block design with three replications. The first factor consisted of four nitrogen levels (control" without nitrogen application"), 30% less than optimum level, optimum level "on the basis of optimum level soil residue nitrate", and 30% more than optimum level). The second factor consisted of three varieties (Rasoul" as regional control", Sharif "SBSI001", and Palma). The result of combined analysis showed that nitrogen application on root yield, sugar content, and other root quality traits (white sugar, molasses content) was significant. Moreover, with higher use of nitrogen, sugar yield decreased, but other quality indices (Na, K, etc) increased. The effect of variety on the traits studied was significant including root and white sugar yields. Palma variety had the highest root yield and white sugar yield compared to other varieties. Also, with more nitrogen application, efficiency parameters (use, utilization and uptake) decreased. The interaction of treatments was significant on the traits such as sugar percentage, white sugar percentage, and molasses sugar content, such that Palma variety was better in terms of the above indicators. The interaction of treatments was not significant on efficiency indices, but Palma cultivar, compared to other varieties, had the highest use and utilization efficiency. Therefore, to achieve economic yield of white sugar in this region and for conditions similar to this experiment, application of nitrogen at 30% less than the optimum rate and use of plma variety is recommended followed by Sharif and Rasoul varieties.