Estimation of Heterosis and Combining Ability in Some Bread Wheat Crosses

This study was carried out within the cooperation between faculty of agricultural at al ba`ath university,the general commission of agricultural scientific research in jossiet al-kharab research center andkarahta station of field crops research during 2007-2008 and 2008-2009 seasons. ten highly diverse breadwheat (triticum aestivum l.) genotypes were used in the crossing block; gairwel7, azaz1, florance-auror, sham4, bouhoos8, douma4, sham8, douma2, zemamara1, and soued, and crossed using halfdiallel cross mating method. the derived crosses along with their parents were grown in the second year,using a randomized complete block design with three replications to estimate general combining ability,specific combining ability, and both mid and better parent heterosis for traits, number of days to heading,plant height, grain yield per plant, number of spikes per plant, number of grains per spike, and thousandkernel weight. the results indicated non-additive type of gene action was predominant in some traitinheritance, including number of days to heading, grain yield per plant, number of spikes per plant, numberof grains per spike. also, it was found that additive and non-additive gene effects were equally included inthe control of some trait including thousand kernel weight, but the preponderance of the additive geneaction was noted plant height inheritance. three parents had the high general combiners for grain yield,yield components. these were douma4, bouhoos8 and sham4. thus, progenies derived from these parentsin a bread wheat program would have highly inherit their characters. many positive specific combinershaving both mid-and high-parent heterosis were derived from positive general combiners including(gairwel7 x bouhoos8), (gairwel7 x douma4), (azaz1 x bouhoos8), (azaz1 x douma4) and (azaz1 xsham8).