Genetic Analysis of Agronomic Traits in Some Oriental-Type Tobacco (Nicotiana tabaccum) Genotypes Using Diallel Crossing

To estimate genetic parameters of agronomic traits in tobacco, six oriental-type tobacco varieties were crossed based on diallel mating system without reciprocals in 2013. F1 populations and six parental lines were planted using randomized complete block design with three replications in 2014 at research field of Urmia Tobacco Research Center, Urmia, Iran. Some charectristics including number of leaves, leaf length and width, plant height, stem diameter, internodes length, fresh leaf and dry weight were measured and analyzed using Griffing method II and mixed effect model B. Analysis of variance revealed significant differences (P≤0.01) between varieties for plant height, leaf number and fresh weight and for leaf dry weight (P≤0.05). General combining ability of varieties for all aforementioned traits was significant at the 1% probability level. Specific combining ability was also significant at the 1% probbaility level for plant height, leaf number and fresh weight. Both additive and non-additive (dominance) gene effects were involved in controlling of plant height, leaf number and fresh weight, however, additive gene effect controlled leaf dry weight. In general, the ratio of GCA to SCA was significant for all of the studied traits except leaf fresh weight which emphasizes the importance of additive effect in inheritance of this trait.