engleski

Heterosis and combining ability analysis for forage yield in alfalfa

The combining ability and heterosis for forage yield of seven previously selected high yielding alfalfa cultivars were estimated using a half-diallel crosses. These cultivars originated from Croatia (OS-88, Slavonka), Denmark (Resis), Bulgaria (Prista), USA (Columbia 2000), Australia (Super 10) and Argentina (Lujan). Forage yield of the 21 F1 progenies and their parents was evaluated during two growing seasons (2008 and 2009) at the experimental field of the Agricultural Institute Osijek in Croatia. The analysis of variance indicated significant differences between parents and F1 progenies for forage yield. An analysis of the components of combining ability showed that general and specific combining ability effects (GCA and SCA) were highly significant. Significant positive general combining ability effects were recorded in parents OS-88 and Columbia 2000. The five F1 progenies were obtained between the six highest-yielding crosses throughout the experiment and they demonstrated significant positive specific combining ability effects. Mid-parent heterosis (MPH) ranged from -18.42 to 61.47% and high-parent heterosis (HPH) ranged from -22.94 to 58.70%. The results of this study indicated that contributions of both GCA and SCA effects were important in explaining variation for forage yield between the alfalfa progenies. Development of progenies superior in yield may be possible by crossing high yielding Medicago sativa cultivars of different geographic origin. Five of nine highest yielding crosses had at least one parent which possessed significant positive GCA effect. These progenies were between the six highest-yielding crosses in the whole experiment. The magnitude of GCA effects was four times larger than that for SCA effects, and five highest yielding crosses demonstrated significant positive SCA effects, indicating relative importance of this effects in determining yield of the progeny. The obtained results showed clearly that alfalfa yield can be improved by exploiting additive and non additive gene effects. The highest yields, significant SCA effects and highest MPH and HPH values were found in the progenies OS-88 x Columbia 2000, OS-88 x Super 10, Slavonka x Columbia 2000 and Slavonka x Super 10, while cultivars OS-88 and Columbia 2000 demonstrated favourable genetic potential that could contribute to the improvement of alfalfa yield in our breeding programme. Our results suggested that the selection based on MPH and HPH could be successful or/and useful in the choice of parental components for the improvement of alfalfa yield in our breeding programme.

alfalfa; combining ability; GCA and SCA effects; heterosis; forage yield

nije evidentirano