Establishment and evaluation of tobacco core germplasm in China
3979 catalogued China tobacco germ plasm collections (35 wild genus are not included) were divided into 4 gradation, 24 groups, according to origination, types, species and ecological distribution. 7-11 qualitative traits as the cluster analyses objects, 824 core germ plasm collection were selected by using system cluster analysis method at 20% selection rate combined with experience. The pre-selected core germ plasms were planted according to their ecological distribution for determination test in 1999. 411 core collections were finally selected at 50% rate with system cluster analysis. Traits mean, standard variance etc. comparison showed that the final selected core germ plasm collections well represented the total collection for genetic diversity with very uniformly distribution, further genetic parameter estimate analysis of 6 main qualitative traits of the core germ plasm collections showed that the traits were highly significantly different in genetic, although the heritability were lower, random environment effect was significant. Three main genetic components variation represented over 90% genetic variation. 3 main components values of 488 genetic sample were obtained as reference for tobacco breeding. The further genetic study on DNA will be carried through.