Combining Ability and Heterosis in Rice (Oryza sativa L.) Cultivars

Quantitative valuations of observed heterosis for 11 traits of 15 f1 hybrids generated byhalf diallel crosses of six diverse rice cultivars (domsefid, hashemi and binam, threeiranian local cultivars; dorfak, kadous and ir30, three improved cultivars), were madein this study. fifteen f1 hybrids and their parents were evaluated in a randomizedcomplete block design with three replications at the research farm of the university ofguilan at rasht, (iran) in 2006. the studied traits were growth period, reproductiveperiod, flag leaf area, plant height, panicle length, number of panicles per plant, numberof grains per panicle, 1000-grain weight, grain yield, brown grain length and brown grainwidth. the significance of specific combining ability (sca) and general combining ability(gca) for all studied traits revealed that both additive and non-additive gene effectscontributed to the inheritance of the traits. assessment of standard heterosis based oncheck variety dorfak showed that there was significant heterosis for all the traits studiedin the 15 hybrids. for grain yield, the dorfak×domsefid cross had the highest heterosis.this hybrid had good heterosis values for many traits such as growth period,reproductive period and 1000-grain weight and was recommended as the most promisingcombination for developing high yielding hybrid rice varieties.