evaluation of general and specific combining ability of sugar beet diploid pollinators

general combining ability of sugar beet parents were determined for different quantity and quality characteristics.forty six sugar beet hybrids obtained from crosses of 23 diploid pollinators with two male sterile parents as tester together with three checks were evaluated for 10 important agronomic and technological characters at kamalshar research station in karaj in 2004.experiment was carried out as a 7*7 lattice design with four replications. there were significant differences between treatments for root yield, sugar content, nitrogen, sodium, potassium, white sugar yield, extractable sugar, sugar yield, purity and molassed sugar at 1% probability level.the check varieties were excluded before the analysis of data for combining abilities. general combining ability of lines was significantly different for sugar content and extractable sugar at 1% and for root yield, sugar yield, white sugar yield, sodium, purity, and molassed sugar at 10% probability level and for potassium at 5% probability level. as the general combining ability was significant for the above traits it could be concluded that they are controlled by additive gene effects.in addition, specific combining ability of lines was significantly different for sugar content, extractable sugar and potassium at 1% and for nitrogen at 5% probability levels.therefor, non-additive effects of genes are involved in the control of  these traits.