and N.I.NENOV 1
1lnstitute for Wheat and Sunflower "Dobroudja" near General Toshevo 9520,Bulgaria
Background and objectives
Phomopsis in sunflower caused by the pyronomycet fungus Phomopsis helianthi Munt. -Cvet. et al. (sexual form Diaporthe helianthi Munt.-Cvet. et al.)spp. seriously damages sunflower production in Bulgaria The most effective means for control of this disease is to create tolerant and resistant sunflower varieties and hybrids. In order to perform successful selection of resistance to Phomopsis, it is necessary to understand the mechanism of genetic resistance inheritance to this pathogen.
Materials and methods
The researches were carried out in the period 1993-1995 in the Institute for Wheat and Sunflower "Dobroudja". The following breeding materials were used: the lines highly sensitive to Phomopsis RHA-265 and RHA-278, line 2547 tolerant to Phomopsis and line 2517 entirely resistant to the pathogen. Direct and back crosses were made with these lines. Two methods for evaluation of the breeding material resistance to Phomopsis helianthi Munt-Cvet. et al. spp. were used: field and greenhouse methods.
Results and conclusions
The resistance of the sunflower lines 2517 and 2547 to Phomopsis helianthi is controlled by several (at least two) different genes. In line 2517 resistance to Phomopsis is controlled by two genes each of which provides resistance to the pathogen, while the tolerance in line 2547 is determined by one gene.
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2.Tourvieille D, Vear F, Pelletier C, 1988 Proceedings of the 12 th International Sunflower
Conference vol.II 110-114