Breeding of an extremely low nicotine Burley tobacco line and its characteristics
Worldwide, regulation on tobacco and cigarettes is increasing more and more. In addition, the U.S. Food and Drug Administration (FDA) has recently announced a plan for regulation of nicotine content in tobacco. In this situation, not only flue-cured varieties, the major raw material, but also Burley varieties, the supplementary raw material, have been required to lower nicotine content. Effective methods for reducing nicotine in the cigarette manufacturing process have been studied. However, the nicotine content in tobacco is affected by genetics, environmental conditions and cultural practices. Cured leaves with less than 0.5 % nicotine content have a poor smoking taste. But, due to the recent tightening of nicotine regulation, it is necessary to breed a new variety with less unfavourable substances. The objective of this study was to breed a variety of Burley tobacco which had low nicotine content, was resistant to potato virus Y (PVY) and black shank. The new Burley tobacco line, BLN-5, was developed by crossing a low alkaloid line and a KT&G breeding line KB110 with PVY resistance. The KRATF’s drop test method for rapid estimation of alkaloid content and isatin coloration method for identifying low nicotine converters of tobacco were used in the selection procedures, respectively. The agronomic traits of BLN-5 line were very similar to those of KB108 as standard cultivar. It showed vigorous growth in the field and was almost the same as KB108 in days to flowering. The yield of cured leaf was approximately 1-2 % less than that of KB108 but its other agronomic characteristics were very similar to those of KB108. BLN-5 line was also resistant to PVY and black shank. In the performance test, the nicotine content of BLN-5 was approximately 86 % lower than that of KB108. Also, it had wider leaves than KB108 and it was almost the same as KB108 in days to flowering.