Effect of soil nitrogen on some physiological characteristics and quality of sugar beet

There are different methods for crop fertilizing nowadays. This study was conducted to assess effects of soil nitrogen on sugar beet traits such as chlorophyll content (SPAD) and also possibility of use of SPADfor sugar beet varieties differentiation as well as a distinguishing lack of nitrogen. A factorial experiment based on completely randomized blocks design with four replications was conducted. The first factor was domestic (Zarghan) and foreign (Flores) sugar beet cultivars and second factor was four nitrogen levels (control, 70, 100 and 130 kg N ha from urea). Sugar content, root and white sugar yields, SPADand application of nitrogen fertilizer of Flores were more and its petiole total nitrogen was less than Zarghan. The most percentage of root yield increase in both varieties was observed in application of 100 kg/ha.in comparison with control treatment. There were positive and significant correlation between sugar beet root yield with blade and petiole total nitrogenand radiation absorption during harvest time and also between root and white sugar yield with SPAD at 8-12 leaf growth stage (June) and also SPAD with blade total nitrogen at the same time. So SPADcould be used in sugar beet establishment growth stage for evaluation of nitrogen status and also for sooner line and hybrid selection. If the value of chlorophyll meter in the bottom of fifth leaf was lower than 45 at establishment, root yield would be increased by nitrogen fertilizer application. Also sugar beet selection would be faster by calibration of this method.