A Study On Nitrogen Absorption And Distribution In Sugar Beet With ¹⁵N Tracer Technique

15N isotope tracer technique was used in this field micro-plot trials to study the nitrogen accumulation, distribution rules and nitrogen use efficiency of beet under different nitrogen levels. The experimental design 4 processing:NO,N 1,N2,N3, nitrogen application rates were Okg/hm2,50 kg/hm2,100 kg/hm2,150 kg/hm2. Determination of nitrogen content and 15N abundance in different beet organs of the various growth stages, calculation of nitrogen accumulation and fertilizer nitrogen accumulation in various beet organs. Main results are shown as following:1. Different parts of the beets in the whole growth of different nitrogen accumulation change. Beet aerial parts (petiole, blade) of the accumulation and the distribution proportion of nitrogen was significantly greater than the of beer underground parts (roots) in the early growth stage of beet. Beet underground parts of the accumulation and the distribution proportion of nitrogen was gradually over the of beet aerial parts in the late growth stage. Application of nitrogen can increase the amount of nitrogen accumulated and nitrogen absorption intensity in various beet organs. The nitrogen distribution in the upper part of the early stage of the sugar beet was affected by nitrogen fertilizer2. Beet nitrogen absorbed mainly from soil nitrogen, the proportion of fertilizer nitrogen is less. Beet seedling stage of various organs have the highes proportion of nitrogen fertilizer, beet of various organs in the proportion of nitrogen fertilizer decreased with the growth progress. At low nitrogen levels with the increasing amount of nitrogen, can significantly increase the proport’ in the beet organs of nitrogen fertilizer. After reaching a certain level of nitroged increasing nitrogen application can not significantly increase the proportion of nitrogen fertilizers in sugar beet plants.3. With the growth progress, nitrogen utilization in a gradual increase in sugar beet, it began to decline in the late growth stage. There was no necessary connection between the increase of N use efficiency and the increase of N application rate. Beet nitrogen utilization rate of up to 37.55% in this experiment.4. Beet root to shoot ratio is increasing with the growth progress. Beet root to shoot ratio is less than I and growth center on the aerial parts in June, July. After August, beet root to shoot ratio is greater than I, growth center in the underground part, the growth center transfer period between July to August. Increase the amount of nitrogen can increase the weight of sugar beet plants, does not affect the sugar beet growth center transfer.5. The beet root yield increases, with the increase of nitrogen application. in a certain level of nitrogen, beet root sugar content increases with the amount of nitrogen becomes high, sugar content decreased significantly if more than a (?)tain level of nitrogen.6. The beet aerial parts plant nitrogen accumulation and nitrogen use fficiency have declined in the late stage of growth and development of sugar bcet, it indicate nitrogen accumulation of beet canopy presence losses in the late growth stage. Beet canopy N loss may be due to beet canopy nitrogen leaching and volatilization in the late fertility caused. Loss manner of beet canopy nitrogen, loss morphology and loss mechanism is not clear, therefore, beet canopy nitrogen loss by further research needs to be done.