Diallel Cross Analysis in Sugar Beet (Beta vulgaris L.): Identification of the Best Parents and Hybrids for Resistance to Bolting and Cercospora Leaf Spot in Sugar Beet Monogerm O-type Lines

Aims: In order to identify the best parents and hybrids for resistance to Bolting and Cercospora leaf spot 9 sugar beet O-type lines in format method of Diallel 9×9 were crossed.
Study design: 9 Sugar beet O-type lines in format method of 9×9 4 Diallel crossing was performed using II Griffing's method were crossed and with four control treatments in a triple lattice design with three replicates.
Place and Duration of Study: Safiabad Agricultural Research Center, Dezful, Iran during 2008-2009 growing season.
Methodology: Analysis of combining ability by using Griffing's method II Diallel crossing scheme after elimination of the control treatments. KWS scale from 1 to 9 (1= healthy plants and 9 = maximum injury) was used to estimation of resistance to Cercospora disease.
Results: General combining ability of O-types was significant for potassium, alpha amino nitrogen and alkalinity at 1% and for resistance to Bolting and Cercospora, molassed sugar, root yield, sugar yield and white sugar yield at 5% probability levels. Also, specific combining ability was significant for resistance to Bolting, potassium, root yield and sugar yield at 1% and for resistance to Cercospora and white sugar yield at 5% probability levels.
Conclusion: Additive and non-additive gene effects control the expression of resistance to Cercospora and white sugar yield. Also, resistance to Bolting was found to be mainly determined by the non-additive gene effects. The best parent and hybrid for resistance to Cercospora were RR607 and RR607 × 452, respectively. Furthermore, the best parent and hybrid for resistance to Bolting were 7173-36 and 436 × 436, respectively. Also the best parent for double resistance to Cercospora and bolting were RR607 and RR607×436 and RR607×7112-36 is the best hybrids.