I assume that you are referring to this type of tobacco cv.: Nicotiana tabacum L. cv. Petit Havana SR1. We simply call them SR1 tobacco. Many labs use them for research due to its small architecture (as oppose to cv. Wisconsin 38).
I saw your institute is located in the US, so you can start with this company (see website): http://www.arabidopsis.com/main/cat/seeds/tobacco/!ts.html
If you just need some free seeds to start your research, you can also email Plant Gene Expression Center (USDA-ARS, located at Albany, CA) greenhouse manger to ask for some. They have wild type (non-transgenic) SR1 tobacco seed stock.
I have a basic doubt. Kindly reply if anybody knows it. Is there any difference between Nicotiana tabacum cv.Petite havana and Nicotiana tabacum cv.petite havana SR1???