Jirasak Apisitsantikul¹, Uthai Chaiboonyoung² and Sawate Muninphithak²

1 Mae Jo Tobacco Experiment Station, San Sai, Chiang Mai 50209

2 Mae Lane Tobacco Station, San Kamphaeng, Chiang Mai 50209

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The F3 flue-cured tobacco families, CCK-6-1, CCK-8-3, CCK-8-1, CCK-7-1, and CCK-8-2, were evaluated for yield, quality and agronomic characteristics in comparison with the check variety K 346 using stripe test of 400 plants per families during October 2003 to March 2004 at Mae Lane Tobacco station, Chiang Mai. As a result, they gave higher cured leaf yield than K 346 by 33.4, 32.5, 23.0, 11.3, and 6.4%, respectively. Outstanding F3 plants within two best families or lines: CCK-6-1 and CCK-8-3 were further selected for improvement in the breeding program. As such, 15 F3 plants were selected: CCK-6-1-1, CCK-6-1-2, CCK-6-1-3, CCK-6-1-4, CCK-6-1-5, CCK-6-1-6, CCK-6-1-7, CCK-6-1-8, CCK-6-1-9, CCK-6-1-10, CCK-6-1-11, CCK-6-1-12, CCK-6-1-13, CCK-6-1-14, and CCK-6-1-15 from CCK-6-1 (K 326-3 x NC 27 NF), 8 F3 plants were selected: CCK-8-3-1, CCK-8-3-2, CCK-8-3-3, CCK-8-3-4, CCK-8-3-5, CCK-8-3-6, CCK8-3-7, and CCK-8-3-8 from CK-8-3. All 23 selected plants produced fresh and cured leaf yields significantly higher than K 346. Chemical analysis of cured leaves indicate that the levels of nicotine and reducing sugars ranged from 2,026 to 4,062 and 19.21 to 26.98%, respectively. The ratio of reducing sugars to nicotine ranged from 4.16 to 11.94. It is suggested that further selection for high yield and quality in the next generation will be the main objective to be achieved by accumulating the additive genes from one generation to the following generations.