Relationship between genetic distance and heterosis in tobacco

Fifteen tobacco parental cultivars of 24 hybrids were classificd into five groups on 4.37 clustering level by the genetic distance calculated on 8 agronomic quantitative characters. The relative cultivars were clustered into the same group. The result of correlation analysis showed that there was a parabola relationship between genetic distance (D2) and yield heterosis (F1/ Mp). When D2 5.63, the correlative coeffcient was significant(r= 0.511 * * ), and the heterosis increased with the increasing of genetic distance.When D2 5.63, the heterosis decreased with the increasing of genetic distance. Therefore, in order to obtain higher heterosis of yield in tobacco, it might be better to choose cultivars with small to medium genetic distance as crossing parents.