Invader Shoots with Invaded Roots on Diallel Analysis of Oriental Tobacco Genotypes under Egyptian Broomrape Stress

Egyptian broomrape (EBR) (Orobanche aegyptiaca Pers. is one of the most dangerous parasitic plants for a broad spectrum of hosts including tobacco (Nicotiana tabaccum L.). Finding genotypes resistant to EBR in Oriental tobacco, one of the main types of tobacco is of great importance and is one of the breeding aims in fighting against this parasite in Iran. In this strategic direction, a research work using diallel analysis was conducted to identify resistant Oriental tobacco genotypes against EBR at Urmia Tobacco Research Centre, Iran in 2012. Fifteen F1 progenies along with their six parents were planted in randomized complete block design with three replications in two separate experiments. Analysis of variance of investigated traits [fresh weight of root (FWR) and dry weight of root (DWR) for host plants, and fresh weight of broomrape shoot (FWBS), dry weight of broomrape shoot (DWBS) and number of broomrape shoots (NBS) for parasite plants] using diallel analysis showed significant mean squares of specific combining ability (SCA) for DWR, DWBS and NBS indicating the importance of non-additive genetic effects for these traits. Good and poor general combiners were not determined among parents for investigated traits due to non-significance of general combining ability (GCA). A set of hybrids appeared to be significant SCA, which could be used in Oriental tobacco improvement.