Fuente: WIPO "tobacco agriculture" The embodiment of the invention discloses an application of a short N introgressed segment in tobacco and a screening and estimating method thereof. Compared with an N Introgressed segment of Coker176type tobacco, at least 0.93Mb, preferably 1.56 Mb redundant gene components are reduced at the right end of an N gene for the short N introgressed segment. A tobacco plant containing the short N introgressed segment resists TMV highly and is free of obvious output and quality disadvantages, and the characters such as output, exogrnous substances and roasting are improved to the maximum extent. The method of estimating the quantity of the redundant gene components deleted in the tobacco plant containing the short N introgressed segment can be used for quickly and accurately screening the plantwith the shortest N introgressed segment from a plurality of plants with short N introgressed segments and selecting the plant with the shortest N introgressed segment to enter a breeding program, sothat the breeding workload can be reduced obviously and the breeding efficiency can be improved obviously.