Effects of Leavse Nitrogen Application Rate on Nitrogen Uptake and Distribution in Soybean

For research the effects of nitrogen uptake and distribution in soybean,Using soybean cultivar‘He Feng50'in Sanjiang Plain in Heilongjiang as test materials and taking15 N tracer method for leaves nitrogen application in R5 to study the nitrogen uptake and distribution of different soybean organs. The results show that there were no signification increments in dry weight, nitrogen content and nitrogen accumulation if the nitrgen application rates were over4. 5kg·hm- 2( N3) and the percentages of soybean seeds dry weight increase over contral were 2. 51%,5. 01%,9. 55%and 0. 51%. The seeds weight had the highest value of 21. 8 g·plant- 1in 4. 5kg·hm- 2( N3) treatment. The different organs15 N accumulation were seed leaf pod petiole root under the same nitrgen application rate. The15 N accumulation of different organs were increased with the nitrgen application rates increased and the seed15 N nitrogen accumulation had the highest value of 8. 17 mg·plant- 1under the different nitrgen application rate. The15 N distribution in seeds reduce with nitrogen application rates from N1 to N3 treatment,but there was a reverse trend in leavse and the seed15 N nitrogen accumulation was increased at the same time. This research theoretically proved that the nitrogen main accumulated to the seeds when leaf nitrogen application in R5 period and in favour of the seeds dry weight accumulation and got high yield at last.