Study on absorption and utilization of nitrogen in flue-cured tobacco plant from rape straw fertilizer with 15N.

A study on absorption and utilization of N in flue-cured tobacco from rape straw fertilizer was conducted by isotopic tracing technology(The rape straw labeled by 15N and NH4NO3 was used as fertilized for tobacco).The results showed: The ration of 15N utilization in tobacco plant from straw fertilizer was lower (0.088 %-5.37 %),which was graded as at upper leaf maturity﹥at middle leaf maturity﹥at lower leaf maturity,leaves﹥stalk﹥roots﹥tips,middle leaves ﹥upper leaves﹥lower leaves.Meanwhile,the residual ration of 15N in soil was higher(75.65 %-85.06 %).Adding the application rate of rape straw could increase the absorption percent of 15N in different parts of tobacco plant.The results also said that,when the rate of application of rape straw fertilizer was 25 %,The utilization ration of 15N in tobacco plant from straw fertilizer was the highest among all the treatments,but the residual ration of 15N in soil was the lowest,and the balanced deviation of 15N was the most appropriate,these are benefit to the utilization of 15N in tobacco plant in those years.However,when the rate of application of rape straw fertilizer was 100 %,the utilization ration of 15N in tobacco plant from straw fertilizer was the lowest and the residual ration of 15N in soil was the highest among all treatments,these could enrich the soil.When the rate of application of rape straw fertilizer was 25 %,the treat of 1/2 NH4NO3 as basic fertilizer and 1/2 NH4NO3 as additional fertilizer could reduce the utilization of 15N in roots,stalk and tip,but add it in leaves and raise the "AN"in soil.